// os — process and filesystem facade. The body of each call lands
// either in libwwrt.a (rt_syscall trampoline) or libc bindings,
// depending on how the program was linked.

@symbol("rt_syscall") fn syscall0(num: i64) i64;
@symbol("rt_syscall") fn syscall1(num: i64, a: i64) i64;
@symbol("rt_syscall") fn syscall2(num: i64, a: i64, b: i64) i64;
@symbol("rt_syscall") fn syscall3(num: i64, a: i64, b: i64, c: i64) i64;
@symbol("rt_syscall") fn syscall4(num: i64, a: i64, b: i64, c: i64, d: i64) i64;

@symbol("rt_alloc") fn alloc(n: u64) *void;
@symbol("rt_free")  fn free(p: *void, n: u64) void;
@symbol("rt_abort") fn abort(msg: str) void;

// Hare-style runtime check. Caller passes a message that's printed
// to stderr before exit(1).
export fn assert(cond: bool, msg: str) void = {
	if (!cond) { abort(msg); };
};

def SYS_READ:   i64 = 0;
def SYS_WRITE:  i64 = 1;
def SYS_OPEN:   i64 = 2;
def SYS_CLOSE:  i64 = 3;
def SYS_LSEEK:  i64 = 8;
def SYS_ACCESS: i64 = 21;
def SYS_DUP2:   i64 = 33;
def SYS_GETPID: i64 = 39;
def SYS_FORK:   i64 = 57;
def SYS_EXECVE: i64 = 59;
def SYS_EXIT:   i64 = 60;
def SYS_WAIT4:  i64 = 61;
def SYS_UNLINK: i64 = 87;

// open(2) flags. Linux values, matching <fcntl.h>.
def O_RDONLY: i32 = 0;
def O_WRONLY: i32 = 1;
def O_RDWR:   i32 = 2;
def O_CREAT:  i32 = 64;		// 0x40
def O_TRUNC:  i32 = 512;	// 0x200

// lseek(2) whence.
def SEEK_SET: i32 = 0;
def SEEK_CUR: i32 = 1;
def SEEK_END: i32 = 2;

export fn exit(code: i32) void = {
	syscall1(SYS_EXIT, code: i64);
};

// Raw, non-fallible primitives. These return Linux's int conventions
// (negative = -errno, non-negative = bytes/fd/etc). Callers wanting a
// Hare-style fallible API use the wrappers below.
export fn write(fd: i32, buf: *u8, n: u64) i64 = {
	return syscall3(SYS_WRITE, fd: i64, buf: i64, n: i64);
};

export fn read(fd: i32, buf: *u8, n: u64) i64 = {
	return syscall3(SYS_READ, fd: i64, buf: i64, n: i64);
};

export fn close(fd: i32) i32 = {
	return syscall1(SYS_CLOSE, fd: i64): i32;
};

// dup2(2): make `newfd` refer to the same description as `oldfd`,
// closing `newfd` first if open. Returns `newfd` on success or a
// negative errno. Used by 6c_ww to redirect stdout into an output
// file without changing the cgen emit path.
export fn dup2(oldfd: i32, newfd: i32) i32 = {
	return syscall2(SYS_DUP2, oldfd: i64, newfd: i64): i32;
};

// Fallible wrappers. The error variant is a plain str (Plan 9 errstr
// model, see lib/errors); the sum type makes success/failure explicit
// without overloading length-zero.
export fn tryread(fd: i32, buf: *u8, n: u64) (i64 | str) = {
	let r: i64 = read(fd, buf, n);
	if (r < 0) { return "read failed"; };
	return r;
};

export fn trywrite(fd: i32, buf: *u8, n: u64) (i64 | str) = {
	let r: i64 = write(fd, buf, n);
	if (r < 0) { return "write failed"; };
	return r;
};

// open — Linux open(2). Path must be NUL-terminated; callers using ww
// `str` must ensure the bytes are followed by a 0 byte (literals are,
// arena-copied paths usually are by construction). Returns -errno on
// failure, fd otherwise. Higher-level callers prefer `tryopen`.
export fn open(path: *u8, flags: i32, mode: i32) i32 = {
	return syscall3(SYS_OPEN, path: i64, flags: i64, mode: i64): i32;
};

export fn tryopen(path: *u8, flags: i32, mode: i32) (i32 | str) = {
	let fd: i32 = open(path, flags, mode);
	if (fd < 0) { return "open failed"; };
	return fd;
};

// lseek — set/inspect the fd's position. Returns the new offset or
// a negative errno. We use this for fstat-free file-size discovery
// (open ⇒ lseek to end ⇒ lseek back).
export fn lseek(fd: i32, off: i64, whence: i32) i64 = {
	return syscall3(SYS_LSEEK, fd: i64, off, whence: i64);
};

// filesize — convenience: returns the byte length of an open fd by
// seeking to the end and back. -1 on error.
export fn filesize(fd: i32) i64 = {
	let end: i64 = lseek(fd, 0i64, SEEK_END);
	if (end < 0) { return -1i64; };
	let r: i64 = lseek(fd, 0i64, SEEK_SET);
	if (r < 0) { return -1i64; };
	return end;
};

// readfull — keep reading until `n` bytes have arrived or the fd
// closes early. Returns bytes read (0..=n) or -1 on read error.
export fn readfull(fd: i32, buf: *u8, n: u64) i64 = {
	let got: u64 = 0u64;
	for (got < n) {
		let r: i64 = read(fd, buf + got, n - got);
		if (r < 0) { return -1i64; };
		if (r == 0) { return got: i64; };	// short read: caller decides
		got += r: u64;
	};
	return got: i64;
};

// writefull — keep writing until `n` bytes have been accepted or the
// fd refuses progress. Returns bytes written or -1.
export fn writefull(fd: i32, buf: *u8, n: u64) i64 = {
	let sent: u64 = 0u64;
	for (sent < n) {
		let r: i64 = write(fd, buf + sent, n - sent);
		if (r < 0) { return -1i64; };
		if (r == 0) { return sent: i64; };
		sent += r: u64;
	};
	return sent: i64;
};

// ---- process and filesystem helpers used by the `ww` driver ----------

// access(2): returns 0 if the file is reachable, negative errno
// otherwise. mode is the bitset described in <unistd.h> (F_OK=0).
export fn access(path: *u8, mode: i32) i32 = {
	return syscall2(SYS_ACCESS, path: i64, mode: i64): i32;
};

// unlink(2).
export fn unlink(path: *u8) i32 = {
	return syscall1(SYS_UNLINK, path: i64): i32;
};

// getpid(2). Used by the driver to mint unique scratch paths.
export fn getpid() i32 = {
	return syscall0(SYS_GETPID): i32;
};

// fork(2): 0 in the child, child pid in the parent, negative errno
// on failure.
export fn fork() i32 = {
	return syscall0(SYS_FORK): i32;
};

// execve(2): on success, does not return.
export fn execve(path: *u8, argv: **u8, envp: **u8) i32 = {
	return syscall3(SYS_EXECVE, path: i64, argv: i64, envp: i64): i32;
};

// wait4(2): wait for `pid` (or any child if -1), store status in
// `*status_out`, return the pid that ended (or negative errno).
export fn wait4(pid: i32, status_out: *i32, options: i32, rusage: *void) i32 = {
	return syscall4(SYS_WAIT4, pid: i64, status_out: i64,
	    options: i64, rusage: i64): i32;
};

// selfhost/cmd/wwc/mem.ww — port of cmd/wwc/mem.c.
//
// Bump arena allocator. Backed by the runtime page allocator
// (rt_alloc / rt_free), no libc. Each chunk is mmap'd; when the
// current chunk runs out we link a fresh one. Freeing the arena
// unmaps the chain.
//
// Memory handed out is 16-byte aligned. The C version under
// cmd/wwc/ is retained until the three-stage bootstrap diffs clean.

use os;

def ALIGN: u64       = 16u64;
def INIT_CHUNK: u64  = 65536u64;
def MAX_CHUNK: u64   = 4194304u64;
def ARENA_SZ: u64    = 48u64;	// sizeof(arena), kept in sync below

type arena = struct {
	buf:   *u8,
	off:   u64,
	cap:   u64,
	next:  *arena,
	total: u64,
};

fn roundup(n: u64, a: u64) u64 = {
	return (n + a - 1u64) & ~(a - 1u64);
};

export fn newarena() *arena = {
	let a: *arena = os.alloc(ARENA_SZ): *arena;
	a.buf = os.alloc(INIT_CHUNK): *u8;
	a.off = 0u64;
	a.cap = INIT_CHUNK;
	a.next = nil;
	a.total = 0u64;
	return a;
};

// Grow: link a fresh chunk in front of the head. We push the old
// chunk into `next` so the head always describes the current bump
// region. Chunk size doubles up to MAX_CHUNK.
fn grow(a: *arena, need: u64) bool = {
	let want: u64 = a.cap * 2u64;
	if (want < need) { want = need; };
	if (want > MAX_CHUNK) { want = MAX_CHUNK; };
	if (want < need) { return false; };	// single allocation too big

	let old: *arena = os.alloc(ARENA_SZ): *arena;
	old.buf = a.buf;
	old.off = a.off;
	old.cap = a.cap;
	old.next = a.next;
	old.total = 0u64;

	a.buf = os.alloc(want): *u8;
	a.off = 0u64;
	a.cap = want;
	a.next = old;
	return true;
};

export fn amalloc(a: *arena, n: u64) *void = {
	let need: u64 = roundup(n, ALIGN);
	if (need > a.cap - a.off) {
		if (!grow(a, need)) { return nil; };
	};
	let p: *u8 = a.buf + a.off;
	a.off += need;
	a.total += need;
	// Zero the region. Plan 9 amalloc zeroes; we mirror that here so
	// the checker can assume freshly allocated nodes start at 0.
	let i: u64 = 0u64;
	for (i < need) {
		p[i] = 0u8;
		i += 1u64;
	};
	return p: *void;
};

// astrndup — copy `n` bytes into the arena and produce a NUL-terminated
// view. Returns a `str` whose ptr is arena-owned and whose len is `n`
// (the trailing NUL is past `len`, so callers reading exactly n bytes
// see no padding). Used by the lexer to capture token text.
export fn astrndup(a: *arena, src: *u8, n: u64) str = {
	let p: *u8 = amalloc(a, n + 1u64): *u8;
	let i: u64 = 0u64;
	for (i < n) {
		p[i] = src[i];
		i += 1u64;
	};
	p[n] = 0u8;
	let r: str;
	r.ptr = p;
	r.len = n: i32;
	return r;
};

export fn freearena(a: *arena) void = {
	for (a != nil) {
		let next: *arena = a.next;
		os.free(a.buf: *void, a.cap);
		os.free(a: *void, ARENA_SZ);
		a = next;
	};
};

// strconv — number↔string conversions. Decimal i64 to/from a fixed
// buffer. Two error idioms ship side by side:
//   - Plan 9 style (atoi64): tuple `(value, ok)`. Pre-dates the
//     tagged-union work; kept for callers that already use it.
//   - Hare style (parse64/parseu64): `(value | str)`. The error
//     variant carries a short, allocation-free message describing
//     why the parse failed. Prefer this for new code.

// u64toa — write `v` in decimal into `buf` and return the byte count.
// Unsigned-only so callers don't have to think about wraparound when
// printing a u64 that happens to have the high bit set.
export fn u64toa(buf: []u8, v: u64) i32 = {
	let tmp: [32]u8;
	let i: i32 = 0;
	let n: u64 = v;
	for (n > 0u64) {
		tmp[i] = ((n % 10u64) + 48u64): u8;
		n = n / 10u64;
		i += 1;
	};
	if (i == 0) {
		tmp[0] = 48u8;
		i = 1;
	};
	let out: i32 = 0;
	for (i > 0) {
		i -= 1;
		buf[out] = tmp[i];
		out += 1;
	};
	return out;
};

export fn i64toa(buf: []u8, v: i64) i32 = {
	let neg: bool = false;
	let n: i64 = v;
	if (n < 0) {
		neg = true;
		n = -n;
	};
	let tmp: [32]u8;
	let i: i32 = 0;
	for (n > 0) {
		tmp[i] = ((n % 10) + 48): u8;
		n = n / 10;
		i += 1;
	};
	if (i == 0) {
		tmp[0] = 48u8;
		i = 1;
	};
	let out: i32 = 0;
	if (neg) {
		buf[out] = 45u8;	// '-'
		out += 1;
	};
	for (i > 0) {
		i -= 1;
		buf[out] = tmp[i];
		out += 1;
	};
	return out;
};

export fn atoi64(s: str) (i64, bool) = {
	let v: i64 = 0;
	let i: i32 = 0;
	let neg: bool = false;
	if (s.len > 0) {
		if (s[0] == 45u8) { neg = true; i = 1; };
	};
	if (i >= s.len) { return 0, false; };
	for (i < s.len) {
		let c: u8 = s[i];
		if (c < 48u8) { return 0, false; };
		if (c > 57u8) { return 0, false; };
		v = v * 10 + ((c: i64) - 48);
		i += 1;
	};
	if (neg) { v = -v; };
	return v, true;
};

// parse64 — Hare-style fallible signed decimal parser. The value
// variant is i64; the error variant is a short str describing the
// reason. No locale, no whitespace, no underscores: a leading '-' is
// the only non-digit accepted, and only at position 0.
export fn parse64(s: str) (i64 | str) = {
	if (s.len == 0) { return "parse: empty"; };
	let i: i32 = 0;
	let neg: bool = false;
	if (s[0] == 45u8) { neg = true; i = 1; };
	if (i >= s.len) { return "parse: lone sign"; };
	let v: i64 = 0;
	for (i < s.len) {
		let c: u8 = s[i];
		if (c < 48u8) { return "parse: invalid digit"; };
		if (c > 57u8) { return "parse: invalid digit"; };
		v = v * 10 + ((c: i64) - 48);
		i += 1;
	};
	if (neg) { v = -v; };
	return v;
};

// parseu64 — fallible unsigned decimal parser. No leading sign.
export fn parseu64(s: str) (u64 | str) = {
	if (s.len == 0) { return "parse: empty"; };
	let v: u64 = 0u64;
	let i: i32 = 0;
	for (i < s.len) {
		let c: u8 = s[i];
		if (c < 48u8) { return "parse: invalid digit"; };
		if (c > 57u8) { return "parse: invalid digit"; };
		v = v * 10u64 + ((c: u64) - 48u64);
		i += 1;
	};
	return v;
};

// selfhost/cmd/wwc/tok.ww — port of cmd/wwc/tok.c plus the Tkind /
// Tok / Pos shapes from cmd/wwc/ww.h.
//
// Token kind values must stay numerically equal to the C side: the
// 990_selfhost test diffs ww-side wwdump output against C-side
// wwdump output, byte-for-byte. Reordering this list shifts the
// integers and breaks the diff.
//
// Bottom of file: tokprint, which emits one token per line in a
// format identical to cmd/wwc/tok.c:tokprint().

use os;
use strconv;

// ---- Tkind ------------------------------------------------------------
// Mirror of the C enum in cmd/wwc/ww.h. Don't reorder.

def TK_NONE:     i32 = 0;
def TK_EOF:      i32 = 1;
def TK_ERR:      i32 = 2;
def TK_IDENT:    i32 = 3;
def TK_INT:      i32 = 4;
def TK_FLOAT:    i32 = 5;
def TK_RUNE:     i32 = 6;
def TK_STR:      i32 = 7;

def TK_FN:       i32 = 8;
def TK_LET:      i32 = 9;
def TK_DEF:      i32 = 10;
def TK_IF:       i32 = 11;
def TK_ELSE:     i32 = 12;
def TK_FOR:      i32 = 13;
def TK_SWITCH:   i32 = 14;
def TK_CASE:     i32 = 15;
def TK_RETURN:   i32 = 16;
def TK_USE:      i32 = 17;
def TK_TYPE:     i32 = 18;
def TK_STRUCT:   i32 = 19;
def TK_DEFER:    i32 = 20;
def TK_BREAK:    i32 = 21;
def TK_CONTINUE: i32 = 22;
def TK_EXPORT:   i32 = 23;
def TK_PROC:     i32 = 24;
def TK_CHAN:     i32 = 25;
def TK_NIL:      i32 = 26;
def TK_TRUE:     i32 = 27;
def TK_FALSE:    i32 = 28;
def TK_AS:       i32 = 29;
def TK_STATIC:   i32 = 30;
def TK_MATCH:    i32 = 31;

def TK_LPAREN:   i32 = 32;
def TK_RPAREN:   i32 = 33;
def TK_LBRACE:   i32 = 34;
def TK_RBRACE:   i32 = 35;
def TK_LBRACK:   i32 = 36;
def TK_RBRACK:   i32 = 37;
def TK_COMMA:    i32 = 38;
def TK_SEMI:     i32 = 39;
def TK_COLON:    i32 = 40;
def TK_DOT:      i32 = 41;
def TK_ELLIPSIS: i32 = 42;
def TK_DOTDOT:   i32 = 43;
def TK_AT:       i32 = 44;
def TK_QUESTION: i32 = 45;

def TK_ASSIGN:    i32 = 46;
def TK_PLUSEQ:    i32 = 47;
def TK_MINUSEQ:   i32 = 48;
def TK_STAREQ:    i32 = 49;
def TK_SLASHEQ:   i32 = 50;
def TK_PERCENTEQ: i32 = 51;
def TK_AMPEQ:     i32 = 52;
def TK_PIPEEQ:    i32 = 53;
def TK_CARETEQ:   i32 = 54;
def TK_LSHIFTEQ:  i32 = 55;
def TK_RSHIFTEQ:  i32 = 56;

def TK_PLUS:    i32 = 57;
def TK_MINUS:   i32 = 58;
def TK_STAR:    i32 = 59;
def TK_SLASH:   i32 = 60;
def TK_PERCENT: i32 = 61;
def TK_AMP:     i32 = 62;
def TK_PIPE:    i32 = 63;
def TK_CARET:   i32 = 64;
def TK_TILDE:   i32 = 65;
def TK_LSHIFT:  i32 = 66;
def TK_RSHIFT:  i32 = 67;

def TK_EQ:  i32 = 68;
def TK_NEQ: i32 = 69;
def TK_LT:  i32 = 70;
def TK_LE:  i32 = 71;
def TK_GT:  i32 = 72;
def TK_GE:  i32 = 73;

def TK_AND: i32 = 74;
def TK_OR:  i32 = 75;
def TK_NOT: i32 = 76;

def TK_LARROW:   i32 = 77;
def TK_ARROW:    i32 = 78;
def TK_FATARROW: i32 = 79;

def TK_LAST: i32 = 80;

// ---- Pos / Tok --------------------------------------------------------
//
// `pos` is used at error-reporting boundaries; we always pass it via
// *pos so the value never gets struct-copied (6c can't yet copy a
// 24-byte struct).
//
// `tok` is flat — file/line/col live directly on the token rather than
// nested inside a `pos` field. Same reason: nested struct field
// assignment isn't supported, and flat primitives are.

type pos = struct {
	file: str,
	line: i32,
	col:  i32,
};

type tok = struct {
	kind: i32,
	file: str,	// path of the source the token came from
	line: i32,
	col:  i32,
	text: str,	// arena-owned token text (TK_IDENT, TK_STR, TK_ERR)
	uval: u64,	// TK_INT, TK_RUNE
	fval: f64,	// TK_FLOAT
	tsuffix: str,	// typed numeric literal suffix or empty
};

// ---- keyword lookup ---------------------------------------------------

fn streq_n(a: *u8, b: str, n: i32) bool = {
	if (b.len != n) { return false; };
	let i: i32 = 0;
	for (i < n) {
		if (a[i] != b[i]) { return false; };
		i += 1;
	};
	return true;
};

// kwlookup — returns the matching TK_* keyword kind for a byte run,
// or TK_NONE if it's an ordinary identifier. Linear search over a
// small alphabetised list, matching cmd/wwc/tok.c.
export fn kwlookup(p: *u8, n: i32) i32 = {
	if (streq_n(p, "as", n))       { return TK_AS; };
	if (streq_n(p, "break", n))    { return TK_BREAK; };
	if (streq_n(p, "case", n))     { return TK_CASE; };
	if (streq_n(p, "chan", n))     { return TK_CHAN; };
	if (streq_n(p, "continue", n)) { return TK_CONTINUE; };
	if (streq_n(p, "def", n))      { return TK_DEF; };
	if (streq_n(p, "defer", n))    { return TK_DEFER; };
	if (streq_n(p, "else", n))     { return TK_ELSE; };
	if (streq_n(p, "export", n))   { return TK_EXPORT; };
	if (streq_n(p, "false", n))    { return TK_FALSE; };
	if (streq_n(p, "fn", n))       { return TK_FN; };
	if (streq_n(p, "for", n))      { return TK_FOR; };
	if (streq_n(p, "if", n))       { return TK_IF; };
	if (streq_n(p, "let", n))      { return TK_LET; };
	if (streq_n(p, "match", n))    { return TK_MATCH; };
	if (streq_n(p, "nil", n))      { return TK_NIL; };
	if (streq_n(p, "proc", n))     { return TK_PROC; };
	if (streq_n(p, "return", n))   { return TK_RETURN; };
	if (streq_n(p, "static", n))   { return TK_STATIC; };
	if (streq_n(p, "struct", n))   { return TK_STRUCT; };
	if (streq_n(p, "switch", n))   { return TK_SWITCH; };
	if (streq_n(p, "true", n))     { return TK_TRUE; };
	if (streq_n(p, "type", n))     { return TK_TYPE; };
	if (streq_n(p, "use", n))      { return TK_USE; };
	return TK_NONE;
};

// ---- tokname ----------------------------------------------------------
//
// Returns the canonical printable spelling for a token kind. Matches
// the C tokname()'s output exactly so wwdump output diffs cleanly.

export fn tokname(k: i32) str = {
	if (k == TK_NONE)  { return "<none>"; };
	if (k == TK_EOF)   { return "EOF"; };
	if (k == TK_ERR)   { return "ERR"; };
	if (k == TK_IDENT) { return "IDENT"; };
	if (k == TK_INT)   { return "INT"; };
	if (k == TK_FLOAT) { return "FLOAT"; };
	if (k == TK_RUNE)  { return "RUNE"; };
	if (k == TK_STR)   { return "STR"; };

	if (k == TK_FN)       { return "fn"; };
	if (k == TK_LET)      { return "let"; };
	if (k == TK_DEF)      { return "def"; };
	if (k == TK_IF)       { return "if"; };
	if (k == TK_ELSE)     { return "else"; };
	if (k == TK_FOR)      { return "for"; };
	if (k == TK_SWITCH)   { return "switch"; };
	if (k == TK_CASE)     { return "case"; };
	if (k == TK_RETURN)   { return "return"; };
	if (k == TK_USE)      { return "use"; };
	if (k == TK_TYPE)     { return "type"; };
	if (k == TK_STRUCT)   { return "struct"; };
	if (k == TK_DEFER)    { return "defer"; };
	if (k == TK_BREAK)    { return "break"; };
	if (k == TK_CONTINUE) { return "continue"; };
	if (k == TK_EXPORT)   { return "export"; };
	if (k == TK_PROC)     { return "proc"; };
	if (k == TK_CHAN)     { return "chan"; };
	if (k == TK_NIL)      { return "nil"; };
	if (k == TK_TRUE)     { return "true"; };
	if (k == TK_FALSE)    { return "false"; };
	if (k == TK_AS)       { return "as"; };
	if (k == TK_STATIC)   { return "static"; };
	if (k == TK_MATCH)    { return "match"; };

	if (k == TK_LPAREN)   { return "("; };
	if (k == TK_RPAREN)   { return ")"; };
	if (k == TK_LBRACE)   { return "{"; };
	if (k == TK_RBRACE)   { return "}"; };
	if (k == TK_LBRACK)   { return "["; };
	if (k == TK_RBRACK)   { return "]"; };
	if (k == TK_COMMA)    { return ","; };
	if (k == TK_SEMI)     { return ";"; };
	if (k == TK_COLON)    { return ":"; };
	if (k == TK_DOT)      { return "."; };
	if (k == TK_ELLIPSIS) { return "..."; };
	if (k == TK_DOTDOT)   { return ".."; };
	if (k == TK_AT)       { return "@"; };
	if (k == TK_QUESTION) { return "?"; };

	if (k == TK_ASSIGN)    { return "="; };
	if (k == TK_PLUSEQ)    { return "+="; };
	if (k == TK_MINUSEQ)   { return "-="; };
	if (k == TK_STAREQ)    { return "*="; };
	if (k == TK_SLASHEQ)   { return "/="; };
	if (k == TK_PERCENTEQ) { return "%="; };
	if (k == TK_AMPEQ)     { return "&="; };
	if (k == TK_PIPEEQ)    { return "|="; };
	if (k == TK_CARETEQ)   { return "^="; };
	if (k == TK_LSHIFTEQ)  { return "<<="; };
	if (k == TK_RSHIFTEQ)  { return ">>="; };

	if (k == TK_PLUS)    { return "+"; };
	if (k == TK_MINUS)   { return "-"; };
	if (k == TK_STAR)    { return "*"; };
	if (k == TK_SLASH)   { return "/"; };
	if (k == TK_PERCENT) { return "%"; };
	if (k == TK_AMP)     { return "&"; };
	if (k == TK_PIPE)    { return "|"; };
	if (k == TK_CARET)   { return "^"; };
	if (k == TK_TILDE)   { return "~"; };
	if (k == TK_LSHIFT)  { return "<<"; };
	if (k == TK_RSHIFT)  { return ">>"; };

	if (k == TK_EQ)  { return "=="; };
	if (k == TK_NEQ) { return "!="; };
	if (k == TK_LT)  { return "<"; };
	if (k == TK_LE)  { return "<="; };
	if (k == TK_GT)  { return ">"; };
	if (k == TK_GE)  { return ">="; };

	if (k == TK_AND) { return "&&"; };
	if (k == TK_OR)  { return "||"; };
	if (k == TK_NOT) { return "!"; };

	if (k == TK_LARROW)   { return "<-"; };
	if (k == TK_ARROW)    { return "->"; };
	if (k == TK_FATARROW) { return "=>"; };

	if (k == TK_LAST) { return "<last>"; };
	return "<?>";
};

// ---- writer for tokprint ----------------------------------------------
//
// fputq mirrors cmd/wwc/tok.c:fputq — quote the string with C-style
// escapes for \, ", \n, \t, \r and \xNN for other non-printables.

fn fputc_byte(fd: i32, b: u8) void = {
	let buf: [1]u8;
	buf[0] = b;
	os.write(fd, buf.ptr, 1u64);
};

fn fputs_str(fd: i32, s: str) void = {
	os.write(fd, s.ptr, s.len: u64);
};

fn hexchar(n: u8) u8 = {
	if (n < 10u8) { return n + 48u8; };	// '0'..'9'
	return (n - 10u8) + 97u8;		// 'a'..'f'
};

fn fputhex2(fd: i32, b: u8) void = {
	let out: [4]u8;
	out[0] = 92u8;	// '\\'
	out[1] = 120u8;	// 'x'
	out[2] = hexchar(b >> 4u8);
	out[3] = hexchar(b & 15u8);
	os.write(fd, out.ptr, 4u64);
};

fn fputq(fd: i32, p: *u8, n: i32) void = {
	fputc_byte(fd, 34u8);	// '"'
	let i: i32 = 0;
	for (i < n) {
		let c: u8 = p[i];
		if (c == 92u8) {	// '\\'
			fputs_str(fd, "\\\\");
		} else {
			if (c == 34u8) {	// '"'
				fputs_str(fd, "\\\"");
			} else {
				if (c == 10u8) {	// '\n'
					fputs_str(fd, "\\n");
				} else {
					if (c == 9u8) {	// '\t'
						fputs_str(fd, "\\t");
					} else {
						if (c == 13u8) {	// '\r'
							fputs_str(fd, "\\r");
						} else {
							if (c < 32u8) {
								fputhex2(fd, c);
							} else {
								if (c == 127u8) {
									fputhex2(fd, c);
								} else {
									fputc_byte(fd, c);
								};
							};
						};
					};
				};
			};
		};
		i += 1;
	};
	fputc_byte(fd, 34u8);
};

// tokprint — write one token line to fd. Format must match
// cmd/wwc/tok.c:tokprint() byte-for-byte: that's the diff anchor.
//   "<file>:<line>:<col> <kindname>[ <value>]\n"
//
// Takes `t` by pointer because 6c can't yet pass a >16-byte struct
// by value; the C version takes Tok by value.
export fn tokprint(fd: i32, t: *tok) void = {
	// Chained-dot field reads (`t.x.y`) on str sub-fields aren't yet
	// reduced by 6c — `t.x.y` returns the whole str. Lift the str
	// fields into locals so we can use the str pseudo-field path.
	let tfile: str = t.file;
	let ttext: str = t.text;
	if (tfile.len > 0) {
		fputs_str(fd, tfile);
	} else {
		fputs_str(fd, "<none>");
	};
	fputc_byte(fd, 58u8);	// ':'
	let buf: [32]u8;
	let n: i32 = strconv.i64toa(buf[0:32], t.line: i64);
	os.write(fd, buf.ptr, n: u64);
	fputc_byte(fd, 58u8);
	n = strconv.i64toa(buf[0:32], t.col: i64);
	os.write(fd, buf.ptr, n: u64);
	fputc_byte(fd, 32u8);	// ' '
	fputs_str(fd, tokname(t.kind));

	if (t.kind == TK_IDENT) {
		fputc_byte(fd, 32u8);
		fputq(fd, ttext.ptr, ttext.len);
	} else { if (t.kind == TK_STR) {
		fputc_byte(fd, 32u8);
		fputq(fd, ttext.ptr, ttext.len);
	} else { if (t.kind == TK_ERR) {
		fputc_byte(fd, 32u8);
		fputq(fd, ttext.ptr, ttext.len);
	} else { if (t.kind == TK_INT) {
		fputc_byte(fd, 32u8);
		n = strconv.u64toa(buf[0:32], t.uval);
		os.write(fd, buf.ptr, n: u64);
	} else { if (t.kind == TK_RUNE) {
		fputc_byte(fd, 32u8);
		n = strconv.u64toa(buf[0:32], t.uval);
		os.write(fd, buf.ptr, n: u64);
	};};};};};
	// TK_FLOAT is intentionally not handled here — %g formatting
	// won't byte-match across implementations. Diff fixtures must
	// be float-free until we implement a stable float formatter.

	fputc_byte(fd, 10u8);	// '\n'
};

// ascii — byte-class predicates and case folding for the ASCII range.
// Matches Hare's ascii::isdigit family. Bytes outside 0..127 always
// answer `false`. The lexer hot path uses these inline; they are
// expected to inline to a couple of compares.

export fn isdigit(c: u8) bool = {
	if (c < 48u8) { return false; };
	if (c > 57u8) { return false; };
	return true;
};

export fn isupper(c: u8) bool = {
	if (c < 65u8) { return false; };
	if (c > 90u8) { return false; };
	return true;
};

export fn islower(c: u8) bool = {
	if (c < 97u8) { return false; };
	if (c > 122u8) { return false; };
	return true;
};

export fn isalpha(c: u8) bool = {
	if (isupper(c)) { return true; };
	return islower(c);
};

export fn isalnum(c: u8) bool = {
	if (isalpha(c)) { return true; };
	return isdigit(c);
};

// isspace — the C/Hare set: space, tab, NL, VT, FF, CR.
export fn isspace(c: u8) bool = {
	if (c == 32u8) { return true; };	// ' '
	if (c == 9u8)  { return true; };	// '\t'
	if (c == 10u8) { return true; };	// '\n'
	if (c == 11u8) { return true; };	// '\v'
	if (c == 12u8) { return true; };	// '\f'
	if (c == 13u8) { return true; };	// '\r'
	return false;
};

export fn ishex(c: u8) bool = {
	if (isdigit(c)) { return true; };
	if (c >= 65u8) {
		if (c <= 70u8) { return true; };	// 'A'..'F'
	};
	if (c >= 97u8) {
		if (c <= 102u8) { return true; };	// 'a'..'f'
	};
	return false;
};

// digitval — value of `c` as a hex/decimal digit, or -1 if not one.
// Useful when scanning numeric literals.
export fn digitval(c: u8) i32 = {
	if (isdigit(c)) { return (c - 48u8): i32; };
	if (c >= 65u8) {
		if (c <= 70u8) { return ((c - 65u8) + 10u8): i32; };
	};
	if (c >= 97u8) {
		if (c <= 102u8) { return ((c - 97u8) + 10u8): i32; };
	};
	return -1;
};

// isidstart / isidpart — identifier classes used by the lexer.
// Alpha or '_' starts; alnum or '_' continues.
export fn isidstart(c: u8) bool = {
	if (isalpha(c)) { return true; };
	if (c == 95u8) { return true; };	// '_'
	return false;
};

export fn isidpart(c: u8) bool = {
	if (isalnum(c)) { return true; };
	if (c == 95u8) { return true; };
	return false;
};

// tolower / toupper — fold ASCII case. Non-letters pass through.
export fn tolower(c: u8) u8 = {
	if (isupper(c)) { return c + 32u8; };
	return c;
};

export fn toupper(c: u8) u8 = {
	if (islower(c)) { return c - 32u8; };
	return c;
};

// selfhost/cmd/wwc/lex.ww — port of cmd/wwc/lex.c.
//
// The DFA, the helpers, and the order of decisions all mirror the C
// version exactly. The 990_selfhost test diffs the resulting token
// stream against the C-side wwdump byte-for-byte; any divergence is
// a port bug.
//
// Calling-convention note: 6c can't yet pass or return structs >16
// bytes by value, so `tok` and `pos` are passed by pointer (out
// params). The C version passes `Tok` by value; we differ here only
// in shape, not in observable behaviour. Token kind values stay
// numerically identical.

use os;
use ascii;
use mem;
use tok;

type lex = struct {
	file:   str,
	src:    *u8,	// raw bytes; not necessarily NUL-terminated
	srclen: u64,
	lpos:   u64,
	line:   i32,
	col:    i32,
	a:      *arena,
	errs:   i32,
};

export fn lexinit(l: *lex, a: *arena, file: str, src: *u8, len: u64) void = {
	l.file = file;
	l.src = src;
	l.srclen = len;
	l.lpos = 0u64;
	l.line = 1;
	l.col = 1;
	l.a = a;
	l.errs = 0;
};

// srcb — byte at offset; helper that lifts the cast out of indexing.
fn srcb(l: *lex, off: u64) i32 = {
	let i: i32 = off: i32;
	let b: u8 = l.src[i];
	return b: i32;
};

fn lpeek(l: *lex, ahead: u64) i32 = {
	let p: u64 = l.lpos + ahead;
	if (p >= l.srclen) { return -1; };
	return srcb(l, p);
};

fn lget(l: *lex) i32 = {
	if (l.lpos >= l.srclen) { return -1; };
	let c: i32 = srcb(l, l.lpos);
	l.lpos += 1u64;
	if (c == 10) {	// '\n'
		l.line += 1;
		l.col = 1;
	} else {
		l.col += 1;
	};
	return c;
};

fn cur_pos(l: *lex, out: *pos) void = {
	out.file = l.file;
	out.line = l.line;
	out.col = l.col;
};

// putuint — write `v` (signed, but always non-negative here) to fd 2
// in decimal. Standalone so err_at doesn't drag in fmt and create a
// dependency cycle with strconv.
fn putuint(fd: i32, v: i32) void = {
	let tmp: [16]u8;
	let i: i32 = 0;
	let n: i32 = v;
	for (n > 0) {
		tmp[i] = ((n % 10) + 48): u8;
		n = n / 10;
		i += 1;
	};
	if (i == 0) { tmp[0] = 48u8; i = 1; };
	let buf: [16]u8;
	let m: i32 = 0;
	for (i > 0) { i -= 1; buf[m] = tmp[i]; m += 1; };
	os.write(fd, buf.ptr, m: u64);
};

fn err_at(l: *lex, p: *pos, msg: str) void = {
	let pf: str = p.file;
	os.write(2, pf.ptr, pf.len: u64);
	os.write(2, ":".ptr, 1u64);
	putuint(2, p.line);
	os.write(2, ":".ptr, 1u64);
	putuint(2, p.col);
	os.write(2, ": error: ".ptr, 9u64);
	os.write(2, msg.ptr, msg.len: u64);
	os.write(2, "\n".ptr, 1u64);
	l.errs += 1;
};

fn skipws(l: *lex) bool = {
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) { return false; };
		if (c == 32) { lget(l); continue; };
		if (c == 9)  { lget(l); continue; };
		if (c == 13) { lget(l); continue; };
		if (c == 10) { lget(l); continue; };
		if (c == 47) {	// '/'
			let c2: i32 = lpeek(l, 1u64);
			if (c2 == 47) {
				for (true) {
					let cx: i32 = lpeek(l, 0u64);
					if (cx < 0) { return false; };
					if (cx == 10) { break; };
					lget(l);
				};
				continue;
			};
			if (c2 == 42) {	// '*'
				lget(l); lget(l);
				let prev: i32 = -1;
				for (true) {
					let x: i32 = lget(l);
					if (x < 0) {
						let cp: pos;
						cur_pos(l, &cp);
						err_at(l, &cp, "unterminated /* comment");
						return false;
					};
					if (prev == 42) {
						if (x == 47) { break; };
					};
					prev = x;
				};
				continue;
			};
		};
		return true;
	};
	return false;
};

fn parseint(p: *u8, n: u64, base: i32, ok: *bool) u64 = {
	let v: u64 = 0u64;
	let got: bool = false;
	let i: u64 = 0u64;
	for (i < n) {
		let ix: i32 = i: i32;
		let c: u8 = p[ix];
		if (c == 95u8) {	// '_'
			i += 1u64;
			continue;
		};
		let d: i32 = -1;
		if (c >= 48u8) {
			if (c <= 57u8) { d = (c - 48u8): i32; };
		};
		if (d < 0) {
			if (c >= 97u8) {
				if (c <= 102u8) { d = ((c - 97u8) + 10u8): i32; };
			};
		};
		if (d < 0) {
			if (c >= 65u8) {
				if (c <= 70u8) { d = ((c - 65u8) + 10u8): i32; };
			};
		};
		if (d < 0) { *ok = false; return 0u64; };
		if (d >= base) { *ok = false; return 0u64; };
		v = v * (base: u64) + (d: u64);
		got = true;
		i += 1u64;
	};
	*ok = got;
	return v;
};

fn escape(l: *lex, out: *i32) bool = {
	let c: i32 = lget(l);
	if (c < 0) { return false; };
	if (c == 110) { *out = 10; return true; };
	if (c == 116) { *out = 9;  return true; };
	if (c == 114) { *out = 13; return true; };
	if (c == 92)  { *out = 92; return true; };
	if (c == 39)  { *out = 39; return true; };
	if (c == 34)  { *out = 34; return true; };
	if (c == 48)  { *out = 0;  return true; };
	if (c == 97)  { *out = 7;  return true; };
	if (c == 98)  { *out = 8;  return true; };
	if (c == 102) { *out = 12; return true; };
	if (c == 118) { *out = 11; return true; };
	if (c == 120) {
		let hi: i32 = lget(l);
		let lo: i32 = lget(l);
		if (hi < 0) { return false; };
		if (lo < 0) { return false; };
		if (!ascii.ishex(hi: u8)) {
			let cp: pos; cur_pos(l, &cp);
			err_at(l, &cp, "bad \\x escape");
			return false;
		};
		if (!ascii.ishex(lo: u8)) {
			let cp: pos; cur_pos(l, &cp);
			err_at(l, &cp, "bad \\x escape");
			return false;
		};
		let h: i32 = ascii.digitval(hi: u8);
		let lv: i32 = ascii.digitval(lo: u8);
		*out = (h << 4) | lv;
		return true;
	};
	let cp: pos; cur_pos(l, &cp);
	err_at(l, &cp, "bad escape");
	return false;
};

// scan_decimal_run — consume a run of decimal digits and underscores.
fn scan_decimal_run(l: *lex) void = {
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) { break; };
		if (!ascii.isdigit(c: u8)) {
			if (c != 95) { break; };
		};
		lget(l);
	};
};

fn scan_hex_run(l: *lex) void = {
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) { break; };
		if (!ascii.ishex(c: u8)) {
			if (c != 95) { break; };
		};
		lget(l);
	};
};

fn scan_bin_run(l: *lex) void = {
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c == 48) { lget(l); continue; };
		if (c == 49) { lget(l); continue; };
		if (c == 95) { lget(l); continue; };
		break;
	};
};

fn scan_oct_run(l: *lex) void = {
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 48) { break; };
		if (c > 55) {
			if (c != 95) { break; };
		};
		lget(l);
	};
};

// scan_exp — consume the [eE][+-]?[0-9]+ tail of a float, if present.
fn scan_exp(l: *lex) void = {
	let e: i32 = lpeek(l, 0u64);
	if (e != 101) { if (e != 69) { return; }; };	// 'e' or 'E'
	lget(l);
	let s: i32 = lpeek(l, 0u64);
	if (s == 43) { lget(l); }
	else { if (s == 45) { lget(l); }; };
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) { break; };
		if (!ascii.isdigit(c: u8)) { break; };
		lget(l);
	};
};

fn lexnum(l: *lex, start: *pos, out: *tok) void = {
	out.kind = TK_INT;
	out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
	let begin: u64 = l.lpos;
	let base: i32 = 10;
	let isfloat: bool = false;

	let c0: i32 = lpeek(l, 0u64);
	let c1: i32 = lpeek(l, 1u64);

	if (c0 == 48) {	// '0'
		if (c1 == 120) {	// 'x'
			lget(l); lget(l); base = 16; scan_hex_run(l);
		} else { if (c1 == 88) {	// 'X'
			lget(l); lget(l); base = 16; scan_hex_run(l);
		} else { if (c1 == 98) {	// 'b'
			lget(l); lget(l); base = 2; scan_bin_run(l);
		} else { if (c1 == 66) {	// 'B'
			lget(l); lget(l); base = 2; scan_bin_run(l);
		} else { if (c1 == 111) {	// 'o'
			lget(l); lget(l); base = 8; scan_oct_run(l);
		} else { if (c1 == 79) {	// 'O'
			lget(l); lget(l); base = 8; scan_oct_run(l);
		} else {
			scan_decimal_run(l);
			if (lpeek(l, 0u64) == 46) {
				let after: i32 = lpeek(l, 1u64);
				if (after >= 48) {
					if (after <= 57) {
						isfloat = true;
						lget(l);
						scan_decimal_run(l);
						scan_exp(l);
					};
				};
			};
		};};};};};};
	} else {
		scan_decimal_run(l);
		if (lpeek(l, 0u64) == 46) {
			let after: i32 = lpeek(l, 1u64);
			if (after >= 48) {
				if (after <= 57) {
					isfloat = true;
					lget(l);
					scan_decimal_run(l);
					scan_exp(l);
				};
			};
		};
	};

	let n: u64 = l.lpos - begin;
	out.text = astrndup(l.a, l.src + begin, n);

	if (isfloat) {
		// out.fval is already 0 from the top-of-lexnext clear.
		// We don't strtod the literal yet — the diff fixtures we
		// care about are float-free; any TK_FLOAT seen in source
		// gets a placeholder value until we wire a real parser.
		out.kind = TK_FLOAT;
	} else {
		let digs: *u8 = l.src + begin;
		let dn: u64 = n;
		if (base != 10) {
			digs = digs + 2u64;
			dn -= 2u64;
		};
		let ok: bool = false;
		out.uval = parseint(digs, dn, base, &ok);
		if (!ok) {
			err_at(l, start, "bad integer literal");
			out.kind = TK_ERR;
		};
	};

	let pc: i32 = lpeek(l, 0u64);
	if (pc >= 0) {
		if (ascii.isidstart(pc: u8)) {
			let sb: u64 = l.lpos;
			for (true) {
				let cc: i32 = lpeek(l, 0u64);
				if (cc < 0) { break; };
				if (!ascii.isidpart(cc: u8)) { break; };
				lget(l);
			};
			let sl: u64 = l.lpos - sb;
			let p: *u8 = l.src + sb;
			let isok: bool = false;
			if (sl == 2u64) {
				if (p[0] == 105u8) {
					if (p[1] == 56u8) { isok = true; };	// i8
				};
				if (p[0] == 117u8) {
					if (p[1] == 56u8) { isok = true; };	// u8
				};
			};
			if (sl == 3u64) {
				if (p[0] == 105u8) {
					if (p[1] == 49u8) { if (p[2] == 54u8) { isok = true; }; };	// i16
					if (p[1] == 51u8) { if (p[2] == 50u8) { isok = true; }; };	// i32
					if (p[1] == 54u8) { if (p[2] == 52u8) { isok = true; }; };	// i64
				};
				if (p[0] == 117u8) {
					if (p[1] == 49u8) { if (p[2] == 54u8) { isok = true; }; };
					if (p[1] == 51u8) { if (p[2] == 50u8) { isok = true; }; };
					if (p[1] == 54u8) { if (p[2] == 52u8) { isok = true; }; };
				};
				if (p[0] == 102u8) {
					if (p[1] == 51u8) { if (p[2] == 50u8) { isok = true; }; };	// f32
					if (p[1] == 54u8) { if (p[2] == 52u8) { isok = true; }; };	// f64
				};
			};
			if (isok) {
				out.tsuffix = astrndup(l.a, p, sl);
			} else {
				l.lpos = sb;
			};
		};
	};
};

fn lexident(l: *lex, start: *pos, out: *tok) void = {
	let begin: u64 = l.lpos;
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) { break; };
		if (!ascii.isidpart(c: u8)) { break; };
		lget(l);
	};
	let n: u64 = l.lpos - begin;
	let p: *u8 = l.src + begin;
	let k: i32 = kwlookup(p, n: i32);
	out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
	if (k != TK_NONE) {
		out.kind = k;
	} else {
		out.kind = TK_IDENT;
	};
	out.text = astrndup(l.a, p, n);
};

fn lexstr(l: *lex, start: *pos, out: *tok) void = {
	let cap: u64 = 32u64;
	let nb:  u64 = 0u64;
	let buf: *u8 = amalloc(l.a, cap): *u8;
	for (true) {
		let c: i32 = lpeek(l, 0u64);
		if (c < 0) {
			err_at(l, start, "unterminated string");
			out.kind = TK_ERR;
			out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
			out.text = astrndup(l.a, "".ptr, 0u64);
			return;
		};
		if (c == 34) { lget(l); break; };
		let ch: i32 = 0;
		if (c == 92) {
			lget(l);
			if (!escape(l, &ch)) { ch = 0; };
		} else {
			ch = lget(l);
		};
		if (nb + 1u64 >= cap) {
			let ncap: u64 = cap * 2u64;
			let nb2: *u8 = amalloc(l.a, ncap): *u8;
			let i: u64 = 0u64;
			for (i < nb) {
				let ix: i32 = i: i32;
				nb2[ix] = buf[ix];
				i += 1u64;
			};
			buf = nb2;
			cap = ncap;
		};
		let nbi: i32 = nb: i32;
		buf[nbi] = ch: u8;
		nb += 1u64;
	};
	out.kind = TK_STR;
	out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
	let s: str;
	s.ptr = buf;
	s.len = nb: i32;
	out.text = s;
};

fn lexrune(l: *lex, start: *pos, out: *tok) void = {
	let c: i32 = lpeek(l, 0u64);
	if (c < 0) {
		err_at(l, start, "unterminated rune");
		out.kind = TK_ERR;
		out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
		out.text = astrndup(l.a, "".ptr, 0u64);
		return;
	};
	let ch: i32 = 0;
	if (c == 92) {
		lget(l);
		if (!escape(l, &ch)) { ch = 0; };
	} else {
		ch = lget(l);
	};
	if (lpeek(l, 0u64) != 39) {
		err_at(l, start, "rune literal missing closing '");
		out.kind = TK_ERR;
		out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
		out.text = astrndup(l.a, "".ptr, 0u64);
		return;
	};
	lget(l);
	out.kind = TK_RUNE;
	out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
	out.uval = ch: u64;
};

fn emit_simple(start: *pos, k: i32, out: *tok) void = {
	out.kind = k;
	out.file = start.file;
	out.line = start.line;
	out.col  = start.col;
};

// set_pos_from — copy file/line/col from a *pos into a tok. Used by
// the err-token path where we already have a pos.
fn set_pos_from(out: *tok, p: *pos) void = {
	out.file = p.file;
	out.line = p.line;
	out.col  = p.col;
};

export fn lexnext(l: *lex, out: *tok) void = {
	// Reset the out token so callers can rely on stale fields being
	// cleared (they only inspect kind, pos, text, uval, fval, tsuffix
	// per kind).
	out.kind = TK_NONE;
	out.uval = 0u64;
	// out.fval starts cleared by the caller's stack-local init (lex.ww
	// allocates the tok with `let t: tok;` which zeroes). We avoid
	// writing a 0.0 literal here so this file itself stays float-free
	// and the C/ww wwdump diff over it is byte-identical.
	let empty: str;
	empty.ptr = nil;
	empty.len = 0;
	out.text = empty;
	out.tsuffix = empty;

	if (!skipws(l)) {
		let p: pos; cur_pos(l, &p);
		emit_simple(&p, TK_EOF, out);
		return;
	};
	let start: pos; cur_pos(l, &start);
	let c: i32 = lpeek(l, 0u64);

	if (c >= 0) {
		if (ascii.isidstart(c: u8)) { lexident(l, &start, out); return; };
		if (ascii.isdigit(c: u8))   { lexnum(l, &start, out); return; };
	};

	if (c == 34) { lget(l); lexstr(l, &start, out); return; };
	if (c == 39) { lget(l); lexrune(l, &start, out); return; };

	lget(l);

	if (c == 40)  { emit_simple(&start, TK_LPAREN, out); return; };
	if (c == 41)  { emit_simple(&start, TK_RPAREN, out); return; };
	if (c == 123) { emit_simple(&start, TK_LBRACE, out); return; };
	if (c == 125) { emit_simple(&start, TK_RBRACE, out); return; };
	if (c == 91)  { emit_simple(&start, TK_LBRACK, out); return; };
	if (c == 93)  { emit_simple(&start, TK_RBRACK, out); return; };
	if (c == 44)  { emit_simple(&start, TK_COMMA, out); return; };
	if (c == 59)  { emit_simple(&start, TK_SEMI, out); return; };
	if (c == 58)  { emit_simple(&start, TK_COLON, out); return; };
	if (c == 64)  { emit_simple(&start, TK_AT, out); return; };
	if (c == 63)  { emit_simple(&start, TK_QUESTION, out); return; };
	if (c == 126) { emit_simple(&start, TK_TILDE, out); return; };

	if (c == 46) {	// '.'
		if (lpeek(l, 0u64) == 46) {
			if (lpeek(l, 1u64) == 46) {
				lget(l); lget(l);
				emit_simple(&start, TK_ELLIPSIS, out); return;
			};
			lget(l);
			emit_simple(&start, TK_DOTDOT, out); return;
		};
		emit_simple(&start, TK_DOT, out); return;
	};

	if (c == 43) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_PLUSEQ, out); return; };
		emit_simple(&start, TK_PLUS, out); return;
	};
	if (c == 45) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_MINUSEQ, out); return; };
		if (lpeek(l, 0u64) == 62) { lget(l); emit_simple(&start, TK_ARROW, out); return; };
		emit_simple(&start, TK_MINUS, out); return;
	};
	if (c == 42) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_STAREQ, out); return; };
		emit_simple(&start, TK_STAR, out); return;
	};
	if (c == 47) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_SLASHEQ, out); return; };
		emit_simple(&start, TK_SLASH, out); return;
	};
	if (c == 37) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_PERCENTEQ, out); return; };
		emit_simple(&start, TK_PERCENT, out); return;
	};
	if (c == 38) {
		if (lpeek(l, 0u64) == 38) { lget(l); emit_simple(&start, TK_AND, out); return; };
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_AMPEQ, out); return; };
		emit_simple(&start, TK_AMP, out); return;
	};
	if (c == 124) {
		if (lpeek(l, 0u64) == 124) { lget(l); emit_simple(&start, TK_OR, out); return; };
		if (lpeek(l, 0u64) == 61)  { lget(l); emit_simple(&start, TK_PIPEEQ, out); return; };
		emit_simple(&start, TK_PIPE, out); return;
	};
	if (c == 94) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_CARETEQ, out); return; };
		emit_simple(&start, TK_CARET, out); return;
	};
	if (c == 61) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_EQ, out); return; };
		if (lpeek(l, 0u64) == 62) { lget(l); emit_simple(&start, TK_FATARROW, out); return; };
		emit_simple(&start, TK_ASSIGN, out); return;
	};
	if (c == 33) {
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_NEQ, out); return; };
		emit_simple(&start, TK_NOT, out); return;
	};
	if (c == 60) {
		if (lpeek(l, 0u64) == 60) {
			lget(l);
			if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_LSHIFTEQ, out); return; };
			emit_simple(&start, TK_LSHIFT, out); return;
		};
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_LE, out); return; };
		if (lpeek(l, 0u64) == 45) { lget(l); emit_simple(&start, TK_LARROW, out); return; };
		emit_simple(&start, TK_LT, out); return;
	};
	if (c == 62) {
		if (lpeek(l, 0u64) == 62) {
			lget(l);
			if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_RSHIFTEQ, out); return; };
			emit_simple(&start, TK_RSHIFT, out); return;
		};
		if (lpeek(l, 0u64) == 61) { lget(l); emit_simple(&start, TK_GE, out); return; };
		emit_simple(&start, TK_GT, out); return;
	};

	err_at(l, &start, "unexpected character");
	out.kind = TK_ERR;
	set_pos_from(out, &start);
	let one: [1]u8;
	one[0] = c: u8;
	out.text = astrndup(l.a, one.ptr, 1u64);
};

// selfhost/cmd/wwc/ast.ww — port of cmd/wwc/ast.c (Node defs + printer).
//
// Status: AST printer is fully ported. Constructor `newnode` is here.
// The parser (parse.ww) is currently minimal — see its file header.
//
// Calling-convention shim: same as tok/lex — `node` is too big to pass
// by value (8 *node pointers + 2 strs + a few ints), so callers always
// hand around `*node`. Only `newnode` allocates and returns a *node.

use os;
use strconv;
use mem;
use tok;

// ---- Nkind ------------------------------------------------------------
//
// Mirror of cmd/wwc/ww.h Nkind. Values must stay numerically equal so
// the AST diff probe in 990_selfhost works.

def N_NONE:     i32 = 0;

def N_INTLIT:   i32 = 1;
def N_FLOATLIT: i32 = 2;
def N_STRLIT:   i32 = 3;
def N_RUNELIT:  i32 = 4;
def N_TRUE:     i32 = 5;
def N_FALSE:    i32 = 6;
def N_NIL:      i32 = 7;
def N_IDENT:    i32 = 8;

def N_BIN:      i32 = 9;
def N_UN:       i32 = 10;
def N_CALL:     i32 = 11;
def N_INDEX:    i32 = 12;
def N_DOT:      i32 = 13;
def N_CAST:     i32 = 14;
def N_STRUCTLIT:i32 = 15;
def N_ARRLIT:   i32 = 16;
def N_FIELD:    i32 = 17;
def N_ASSIGN:   i32 = 18;
def N_ALLOC:    i32 = 19;
def N_FREE:     i32 = 20;
def N_RECV:     i32 = 21;
def N_SLICE:    i32 = 22;
def N_SPREAD:   i32 = 23;

def N_BLOCK:    i32 = 24;
def N_EXPRSTMT: i32 = 25;
def N_LET:      i32 = 26;
def N_RETURN:   i32 = 27;
def N_IF:       i32 = 28;
def N_FOR:      i32 = 29;
def N_FORRANGE: i32 = 30;
def N_DEFER:    i32 = 31;
def N_BREAK:    i32 = 32;
def N_CONTINUE: i32 = 33;
def N_SWITCH:   i32 = 34;
def N_CASE:     i32 = 35;

def N_FILE:     i32 = 36;
def N_USE:      i32 = 37;
def N_DEF:      i32 = 38;
def N_TYPEDECL: i32 = 39;
def N_FNDECL:   i32 = 40;
def N_PARAM:    i32 = 41;

def N_TNAME:    i32 = 42;
def N_TPTR:     i32 = 43;
def N_TSLICE:   i32 = 44;
def N_TARRAY:   i32 = 45;
def N_TFN:      i32 = 46;
def N_TSTRUCT:  i32 = 47;
def N_TFIELD:   i32 = 48;
def N_TCHAN:    i32 = 49;

def N_ATTR:     i32 = 50;
def N_TTUPLE:   i32 = 51;
def N_TTAGGED:  i32 = 52;
def N_TUPLE:    i32 = 53;
def N_MATCH:    i32 = 54;
def N_MCASE:    i32 = 55;
def N_TRYPROP:  i32 = 56;
def N_TRYUNW:   i32 = 57;
def N_MLET:     i32 = 58;
def N_MASSIGN:  i32 = 59;

def N_LAST:     i32 = 60;

// ---- Node -------------------------------------------------------------

type node = struct {
	kind:    i32,
	file:    str,
	line:    i32,
	col:     i32,
	op:      i32,	// for N_BIN / N_UN / N_ASSIGN
	str:     str,
	uval:    u64,
	fval:    f64,
	lhs:     *node,
	rhs:     *node,
	cond:    *node,
	body:    *node,
	els:     *node,
	list:    *node,
	next:    *node,
	attr:    *node,
	exported: i32,	// bool — `export` keyword present
	type_:   *void,	// filled in by checker; type.ww treats it as *tinfo
	tsuffix: str,	// typed numeric literal suffix ("i32", "u64", ...)
};

export fn newnode(a: *arena, k: i32, file: str, line: i32, col: i32) *node = {
	let n: *node = amalloc(a, 192u64): *node;	// 192 ≥ struct size
	n.kind = k;
	n.file = file;
	n.line = line;
	n.col = col;
	return n;
};

// ---- printer ----------------------------------------------------------

fn nkname(k: i32) str = {
	if (k == N_NONE)      { return "none"; };
	if (k == N_INTLIT)    { return "int"; };
	if (k == N_FLOATLIT)  { return "float"; };
	if (k == N_STRLIT)    { return "str"; };
	if (k == N_RUNELIT)   { return "rune"; };
	if (k == N_TRUE)      { return "true"; };
	if (k == N_FALSE)     { return "false"; };
	if (k == N_NIL)       { return "nil"; };
	if (k == N_IDENT)     { return "id"; };
	if (k == N_BIN)       { return "bin"; };
	if (k == N_UN)        { return "un"; };
	if (k == N_CALL)      { return "call"; };
	if (k == N_INDEX)     { return "index"; };
	if (k == N_DOT)       { return "dot"; };
	if (k == N_CAST)      { return "cast"; };
	if (k == N_STRUCTLIT) { return "structlit"; };
	if (k == N_ARRLIT)    { return "arrlit"; };
	if (k == N_FIELD)     { return "field"; };
	if (k == N_ASSIGN)    { return "assign"; };
	if (k == N_ALLOC)     { return "alloc"; };
	if (k == N_FREE)      { return "free"; };
	if (k == N_RECV)      { return "recv"; };
	if (k == N_SLICE)     { return "slice"; };
	if (k == N_SPREAD)    { return "spread"; };
	if (k == N_BLOCK)     { return "block"; };
	if (k == N_EXPRSTMT)  { return "exprstmt"; };
	if (k == N_LET)       { return "let"; };
	if (k == N_RETURN)    { return "return"; };
	if (k == N_IF)        { return "if"; };
	if (k == N_FOR)       { return "for"; };
	if (k == N_FORRANGE)  { return "forrange"; };
	if (k == N_DEFER)     { return "defer"; };
	if (k == N_BREAK)     { return "break"; };
	if (k == N_CONTINUE)  { return "continue"; };
	if (k == N_SWITCH)    { return "switch"; };
	if (k == N_CASE)      { return "case"; };
	if (k == N_FILE)      { return "file"; };
	if (k == N_USE)       { return "use"; };
	if (k == N_DEF)       { return "def"; };
	if (k == N_TYPEDECL)  { return "typedecl"; };
	if (k == N_FNDECL)    { return "fn"; };
	if (k == N_PARAM)     { return "param"; };
	if (k == N_TNAME)     { return "tname"; };
	if (k == N_TPTR)      { return "tptr"; };
	if (k == N_TSLICE)    { return "tslice"; };
	if (k == N_TARRAY)    { return "tarray"; };
	if (k == N_TFN)       { return "tfn"; };
	if (k == N_TSTRUCT)   { return "tstruct"; };
	if (k == N_TFIELD)    { return "tfield"; };
	if (k == N_TCHAN)     { return "tchan"; };
	if (k == N_ATTR)      { return "attr"; };
	if (k == N_TTUPLE)    { return "ttuple"; };
	if (k == N_TTAGGED)   { return "ttagged"; };
	if (k == N_TUPLE)     { return "tuple"; };
	if (k == N_MATCH)     { return "match"; };
	if (k == N_MCASE)     { return "mcase"; };
	if (k == N_TRYPROP)   { return "tryprop"; };
	if (k == N_TRYUNW)    { return "tryunw"; };
	if (k == N_MLET)      { return "mlet"; };
	if (k == N_MASSIGN)   { return "massign"; };
	if (k == N_LAST)      { return "last"; };
	return "?";
};

fn ind(fd: i32, d: i32) void = {
	let i: i32 = 0;
	for (i < d) {
		os.write(fd, "  ".ptr, 2u64);
		i += 1;
	};
};

fn putc1(fd: i32, b: u8) void = {
	let buf: [1]u8;
	buf[0] = b;
	os.write(fd, buf.ptr, 1u64);
};

fn putq(fd: i32, s: str) void = {
	putc1(fd, 34u8);	// '"'
	let i: i32 = 0;
	for (i < s.len) {
		let c: u8 = s[i];
		if (c == 34u8) {		// '"'
			os.write(fd, "\\\"".ptr, 2u64);
		} else { if (c == 92u8) {	// '\\'
			os.write(fd, "\\\\".ptr, 2u64);
		} else { if (c == 10u8) {	// '\n'
			os.write(fd, "\\n".ptr, 2u64);
		} else { if (c == 9u8) {	// '\t'
			os.write(fd, "\\t".ptr, 2u64);
		} else { if (c < 32u8) {
			let hi: u8 = c >> 4u8;
			let lo: u8 = c & 15u8;
			let h: u8 = 0u8;
			let l: u8 = 0u8;
			if (hi < 10u8) { h = hi + 48u8; } else { h = (hi - 10u8) + 97u8; };
			if (lo < 10u8) { l = lo + 48u8; } else { l = (lo - 10u8) + 97u8; };
			let buf: [4]u8;
			buf[0] = 92u8;
			buf[1] = 120u8;
			buf[2] = h;
			buf[3] = l;
			os.write(fd, buf.ptr, 4u64);
		} else {
			putc1(fd, c);
		};};};};};
		i += 1;
	};
	putc1(fd, 34u8);
};

fn pr(fd: i32, n: *node, d: i32) void = {
	if (n == nil) {
		ind(fd, d);
		os.write(fd, "()\n".ptr, 3u64);
		return;
	};
	ind(fd, d);
	putc1(fd, 40u8);	// '('
	let nm: str = nkname(n.kind);
	os.write(fd, nm.ptr, nm.len: u64);

	if (n.kind == N_INTLIT) {
		putc1(fd, 32u8);
		let buf: [32]u8;
		let m: i32 = strconv.u64toa(buf[0:32], n.uval);
		os.write(fd, buf.ptr, m: u64);
	} else { if (n.kind == N_RUNELIT) {
		putc1(fd, 32u8);
		let buf: [32]u8;
		let m: i32 = strconv.u64toa(buf[0:32], n.uval);
		os.write(fd, buf.ptr, m: u64);
	} else { if (
		n.kind == N_STRLIT  ||
		n.kind == N_IDENT   ||
		n.kind == N_USE     ||
		n.kind == N_DOT     ||
		n.kind == N_DEF     ||
		n.kind == N_TYPEDECL ||
		n.kind == N_FNDECL  ||
		n.kind == N_PARAM   ||
		n.kind == N_LET     ||
		n.kind == N_TNAME   ||
		n.kind == N_TFIELD  ||
		n.kind == N_FIELD   ||
		n.kind == N_ATTR
	) {
		// Match C ast.c: print the str field whenever it's non-nil,
		// even if its length is zero (e.g. an empty STRLIT prints
		// `(str ""`).
		let s: str = n.str;
		if (s.ptr != nil) {
			putc1(fd, 32u8);
			putq(fd, s);
		};
	} else { if (
		n.kind == N_BIN ||
		n.kind == N_UN  ||
		n.kind == N_ASSIGN
	) {
		putc1(fd, 32u8);
		let on: str = tokname(n.op);
		os.write(fd, on.ptr, on.len: u64);
	};};};};

	if (n.kind == N_FNDECL) {
		if (n.exported != 0) { os.write(fd, " export".ptr, 7u64); };
	};
	if (n.kind == N_DEF) {
		if (n.exported != 0) { os.write(fd, " export".ptr, 7u64); };
	};
	if (n.kind == N_TYPEDECL) {
		if (n.exported != 0) { os.write(fd, " export".ptr, 7u64); };
	};
	putc1(fd, 10u8);	// '\n'

	if (n.attr != nil) {
		ind(fd, d + 1);
		os.write(fd, "(@\n".ptr, 3u64);
		let m: *node = n.attr;
		for (m != nil) {
			pr(fd, m, d + 2);
			m = m.next;
		};
		ind(fd, d + 1);
		os.write(fd, ")\n".ptr, 2u64);
	};
	if (n.lhs  != nil) { pr(fd, n.lhs,  d + 1); };
	if (n.rhs  != nil) { pr(fd, n.rhs,  d + 1); };
	if (n.cond != nil) { pr(fd, n.cond, d + 1); };
	if (n.body != nil) { pr(fd, n.body, d + 1); };
	if (n.els  != nil) { pr(fd, n.els,  d + 1); };
	if (n.list != nil) {
		ind(fd, d + 1);
		os.write(fd, "(list\n".ptr, 6u64);
		let m: *node = n.list;
		for (m != nil) {
			pr(fd, m, d + 2);
			m = m.next;
		};
		ind(fd, d + 1);
		os.write(fd, ")\n".ptr, 2u64);
	};
	ind(fd, d);
	os.write(fd, ")\n".ptr, 2u64);
};

export fn astprint(fd: i32, n: *node) void = {
	pr(fd, n, 0);
};

// selfhost/cmd/wwc/parse.ww — port of cmd/wwc/parse.c.
//
// Status: GROWING stub. Currently handles top-level `use IDENT;`,
// `def NAME: TYPE = LIT;`, `type NAME = TYPE;`, and `fn NAME(params)
// RET;` (header-only — bodies are recovered past). Unknown decls are
// chewed token-by-token until the next ';' so the diff probe can
// still anchor on partial fixtures.
//
// The full port is multi-session work — parse.c is 1,183 lines of
// hand-rolled recursive descent + Pratt expression parser. Each
// surface form lands here gradually so the AST diff in 990_selfhost
// grows toward whole-language coverage one increment at a time.
//
// Calling-convention shim: 6c can't yet pass a sub-struct field
// (e.g. p.cur.line where p.cur is a `tok` of size 76). The parser
// stores the current token as flat primitive fields rather than a
// nested `tok` struct; `refill` copies a freshly lexed token in.

use os;
use mem;
use tok;

type parser = struct {
	l:    *lex,
	a:    *arena,
	errs: i32,
	// nocast: while inside `[...]` we treat ':' as the slice
	// separator, not the cast operator. Mirrors parse.c's flag.
	nocast: i32,
	cur_kind: i32,
	cur_file: str,
	cur_line: i32,
	cur_col:  i32,
	cur_text: str,
	cur_uval: u64,
};

fn refill(p: *parser) void = {
	let t: tok;
	lexnext(p.l, &t);
	p.cur_kind = t.kind;
	p.cur_file = t.file;
	p.cur_line = t.line;
	p.cur_col  = t.col;
	p.cur_text = t.text;
	p.cur_uval = t.uval;
};

export fn parserinit(p: *parser, a: *arena, l: *lex) void = {
	p.l = l;
	p.a = a;
	p.errs = 0;
	p.nocast = 0;
	refill(p);
};

fn advance(p: *parser) void = { refill(p); };

fn accept_tok(p: *parser, k: i32) bool = {
	if (p.cur_kind == k) { advance(p); return true; };
	return false;
};

fn err_msg(p: *parser, msg: str) void = {
	let pre: str = "parse: ";
	os.write(2, pre.ptr, pre.len: u64);
	os.write(2, msg.ptr, msg.len: u64);
	os.write(2, "\n".ptr, 1u64);
	p.errs += 1;
};

fn expect_tok(p: *parser, k: i32, what: str) bool = {
	if (p.cur_kind == k) { advance(p); return true; };
	err_msg(p, what);
	return false;
};

// expectident — consume the current TK_IDENT and return its text.
// Returns the empty str on error (and advances to make progress).
fn expectident(p: *parser, into: *str) bool = {
	if (p.cur_kind != TK_IDENT) {
		err_msg(p, "expected identifier");
		advance(p);
		return false;
	};
	*into = p.cur_text;
	advance(p);
	return true;
};

// ---- type expressions ------------------------------------------------
//
// Currently: TNAME (single ident, no dotted path yet) and TPTR (`*T`).
// Other forms (slice, array, struct, fn, chan, tuple, tagged) will
// land in subsequent commits.

fn parsetype(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;

	if (p.cur_kind == TK_STAR) {
		advance(p);
		let n: *node = newnode(p.a, N_TPTR, pf, pl, pc);
		n.lhs = parsetype(p);
		return n;
	};

	if (p.cur_kind == TK_LBRACK) {
		advance(p);
		if (p.cur_kind == TK_RBRACK) {
			advance(p);
			let n: *node = newnode(p.a, N_TSLICE, pf, pl, pc);
			n.lhs = parsetype(p);
			return n;
		};
		let n: *node = newnode(p.a, N_TARRAY, pf, pl, pc);
		n.rhs = parseexpr(p);
		expect_tok(p, TK_RBRACK, "expected ']' in array type");
		n.lhs = parsetype(p);
		return n;
	};

	if (p.cur_kind == TK_STRUCT) {
		advance(p);
		expect_tok(p, TK_LBRACE, "expected '{' after struct");
		let n: *node = newnode(p.a, N_TSTRUCT, pf, pl, pc);
		let fhead: *node = nil;
		let ftail: *node = nil;
		for (p.cur_kind != TK_RBRACE) {
			if (p.cur_kind == TK_EOF) { break; };
			let fpf: str = p.cur_file;
			let fpl: i32 = p.cur_line;
			let fpc: i32 = p.cur_col;
			let f: *node = newnode(p.a, N_TFIELD, fpf, fpl, fpc);
			let fid: str;
			expectident(p, &fid);
			f.str = fid;
			expect_tok(p, TK_COLON, "expected ':' in field");
			f.lhs = parsetype(p);
			if (fhead == nil) { fhead = f; ftail = f; }
			else { ftail.next = f; ftail = f; };
			if (!accept_tok(p, TK_COMMA)) { break; };
		};
		expect_tok(p, TK_RBRACE, "expected '}' after struct fields");
		n.list = fhead;
		return n;
	};

	if (p.cur_kind == TK_IDENT) {
		let n: *node = newnode(p.a, N_TNAME, pf, pl, pc);
		n.str = p.cur_text;
		advance(p);
		// Dotted path collapse (pkg.Type) deferred — fixtures don't
		// need it yet.
		return n;
	};

	if (p.cur_kind == TK_LPAREN) {
		// (T)  or  (T, T, ...)  or  (T | T | ...)
		advance(p);
		let first: *node = parsetype(p);
		if (accept_tok(p, TK_PIPE)) {
			let n: *node = newnode(p.a, N_TTAGGED, pf, pl, pc);
			let head: *node = first;
			let tail: *node = first;
			for (true) {
				let e: *node = parsetype(p);
				tail.next = e;
				tail = e;
				if (!accept_tok(p, TK_PIPE)) { break; };
			};
			expect_tok(p, TK_RPAREN, "expected ')' in tagged-union type");
			n.list = head;
			return n;
		};
		if (!accept_tok(p, TK_COMMA)) {
			expect_tok(p, TK_RPAREN, "expected ')' after parenthesised type");
			return first;
		};
		let n: *node = newnode(p.a, N_TTUPLE, pf, pl, pc);
		let head: *node = first;
		let tail: *node = first;
		for (true) {
			let e: *node = parsetype(p);
			tail.next = e;
			tail = e;
			if (!accept_tok(p, TK_COMMA)) { break; };
			if (p.cur_kind == TK_RPAREN) { break; };
		};
		expect_tok(p, TK_RPAREN, "expected ')' in tuple type");
		n.list = head;
		return n;
	};

	if (p.cur_kind == TK_FN) {
		advance(p);
		expect_tok(p, TK_LPAREN, "expected '(' after fn in type");
		let n: *node = newnode(p.a, N_TFN, pf, pl, pc);
		// Anonymous-or-named params: parseparams handles named only;
		// for fn-type expressions the C parser allows IDENT-less
		// (anonymous) params. Stub: only named params for now.
		n.list = parseparams(p);
		expect_tok(p, TK_RPAREN, "expected ')' after fn type params");
		n.lhs = parsetype(p);
		return n;
	};

	err_msg(p, "expected type");
	advance(p);
	return newnode(p.a, N_TNAME, pf, pl, pc);
};

// ---- expressions (Pratt) ---------------------------------------------
//
// Forwards: parseexpr → parsebin → parseunary → parsepostfix(parseprimary).
// Tuple literals, match expressions, struct literals, slice [lo:hi],
// and the ?/! try operators are not yet wired — they'll arrive as the
// AST diff fixture grows to need them.

fn bprec(k: i32) i32 = {
	if (k == TK_OR)        { return 1; };
	if (k == TK_AND)       { return 2; };
	if (k == TK_EQ)        { return 3; };
	if (k == TK_NEQ)       { return 3; };
	if (k == TK_LT)        { return 4; };
	if (k == TK_LE)        { return 4; };
	if (k == TK_GT)        { return 4; };
	if (k == TK_GE)        { return 4; };
	if (k == TK_PIPE)      { return 5; };
	if (k == TK_CARET)     { return 6; };
	if (k == TK_AMP)       { return 7; };
	if (k == TK_LSHIFT)    { return 8; };
	if (k == TK_RSHIFT)    { return 8; };
	if (k == TK_PLUS)      { return 9; };
	if (k == TK_MINUS)     { return 9; };
	if (k == TK_STAR)      { return 10; };
	if (k == TK_SLASH)     { return 10; };
	if (k == TK_PERCENT)   { return 10; };
	return 0;
};

fn isassignop(k: i32) bool = {
	if (k == TK_ASSIGN)    { return true; };
	if (k == TK_PLUSEQ)    { return true; };
	if (k == TK_MINUSEQ)   { return true; };
	if (k == TK_STAREQ)    { return true; };
	if (k == TK_SLASHEQ)   { return true; };
	if (k == TK_PERCENTEQ) { return true; };
	if (k == TK_AMPEQ)     { return true; };
	if (k == TK_PIPEEQ)    { return true; };
	if (k == TK_CARETEQ)   { return true; };
	if (k == TK_LSHIFTEQ)  { return true; };
	if (k == TK_RSHIFTEQ)  { return true; };
	return false;
};

// Forward references between parseunary/parseexpr/parsebin/parsepostfix
// are resolved by the two-pass checker — no body-less prototypes needed.

fn parseprimary(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;

	if (p.cur_kind == TK_INT) {
		let n: *node = newnode(p.a, N_INTLIT, pf, pl, pc);
		n.uval = p.cur_uval;
		n.str = p.cur_text;
		advance(p);
		return n;
	};
	if (p.cur_kind == TK_STR) {
		let n: *node = newnode(p.a, N_STRLIT, pf, pl, pc);
		n.str = p.cur_text;
		advance(p);
		return n;
	};
	if (p.cur_kind == TK_RUNE) {
		let n: *node = newnode(p.a, N_RUNELIT, pf, pl, pc);
		n.uval = p.cur_uval;
		advance(p);
		return n;
	};
	if (p.cur_kind == TK_TRUE) {
		advance(p);
		return newnode(p.a, N_TRUE, pf, pl, pc);
	};
	if (p.cur_kind == TK_FALSE) {
		advance(p);
		return newnode(p.a, N_FALSE, pf, pl, pc);
	};
	if (p.cur_kind == TK_NIL) {
		advance(p);
		return newnode(p.a, N_NIL, pf, pl, pc);
	};
	if (p.cur_kind == TK_LPAREN) {
		advance(p);
		let e: *node = parseexpr(p);
		// Tuple literal: (a, b, ...)
		if (accept_tok(p, TK_COMMA)) {
			let t: *node = newnode(p.a, N_TUPLE, pf, pl, pc);
			t.list = e;
			let tail: *node = e;
			for (true) {
				if (p.cur_kind == TK_RPAREN) { break; };
				let en: *node = parseexpr(p);
				tail.next = en;
				tail = en;
				if (!accept_tok(p, TK_COMMA)) { break; };
			};
			expect_tok(p, TK_RPAREN, "expected ')' in tuple");
			return t;
		};
		expect_tok(p, TK_RPAREN, "expected ')'");
		return e;
	};
	if (p.cur_kind == TK_IDENT) {
		let n: *node = newnode(p.a, N_IDENT, pf, pl, pc);
		n.str = p.cur_text;
		advance(p);
		// `IDENT {` — struct literal. Disambiguate: only consume as a
		// struct lit when we're not in a context where '{' starts a
		// block (e.g. `if (cond) {`). The parser is called from
		// expressions, never directly from cond contexts that need a
		// block; in stmt parsing, the for/if drivers consume their
		// own paren/cond, so this is safe.
		if (p.cur_kind == TK_LBRACE) {
			advance(p);
			let s: *node = newnode(p.a, N_STRUCTLIT, pf, pl, pc);
			s.lhs = n;
			let head: *node = nil;
			let tail: *node = nil;
			for (p.cur_kind != TK_RBRACE) {
				if (p.cur_kind == TK_EOF) { break; };
				let fpf: str = p.cur_file;
				let fpl: i32 = p.cur_line;
				let fpc: i32 = p.cur_col;
				let id: str;
				expectident(p, &id);
				expect_tok(p, TK_ASSIGN, "expected '=' in struct lit field");
				let v: *node = parseexpr(p);
				let f: *node = newnode(p.a, N_FIELD, fpf, fpl, fpc);
				f.str = id;
				f.lhs = v;
				if (head == nil) { head = f; tail = f; }
				else { tail.next = f; tail = f; };
				if (!accept_tok(p, TK_COMMA)) { break; };
			};
			expect_tok(p, TK_RBRACE, "expected '}' after struct literal");
			s.list = head;
			return s;
		};
		return n;
	};
	if (p.cur_kind == TK_MATCH) {
		// match (e) { case let v: T => stmt; case T => stmt; case => stmt; };
		advance(p);
		expect_tok(p, TK_LPAREN, "expected '(' after match");
		let m: *node = newnode(p.a, N_MATCH, pf, pl, pc);
		m.lhs = parseexpr(p);
		expect_tok(p, TK_RPAREN, "expected ')' after match scrutinee");
		expect_tok(p, TK_LBRACE, "expected '{' to open match body");
		let head: *node = nil;
		let tail: *node = nil;
		for (p.cur_kind == TK_CASE) {
			let cf: str = p.cur_file;
			let cl: i32 = p.cur_line;
			let cc: i32 = p.cur_col;
			advance(p);	// past `case`
			let mc: *node = newnode(p.a, N_MCASE, cf, cl, cc);
			if (p.cur_kind == TK_LET) {
				advance(p);
				let id: str;
				expectident(p, &id);
				mc.str = id;
				expect_tok(p, TK_COLON, "expected ':' after match binding");
				mc.lhs = parsetype(p);
			} else { if (p.cur_kind != TK_FATARROW) {
				mc.lhs = parsetype(p);
			};};
			expect_tok(p, TK_FATARROW, "expected '=>' in match arm");
			mc.body = parsestmt(p);
			if (head == nil) { head = mc; tail = mc; }
			else { tail.next = mc; tail = mc; };
		};
		expect_tok(p, TK_RBRACE, "expected '}' after match body");
		m.list = head;
		return m;
	};
	err_msg(p, "expected expression");
	advance(p);
	return newnode(p.a, N_NONE, pf, pl, pc);
};

fn parsearglist(p: *parser, close_kind: i32, head_out: **node) void = {
	*head_out = nil;
	if (p.cur_kind == close_kind) { return; };
	let head: *node = nil;
	let tail: *node = nil;
	for (true) {
		let e: *node = parseexpr(p);
		if (head == nil) { head = e; tail = e; }
		else { tail.next = e; tail = e; };
		if (!accept_tok(p, TK_COMMA)) { break; };
		if (p.cur_kind == close_kind) { break; };
	};
	*head_out = head;
};

fn parsepostfix(p: *parser, lhs: *node) *node = {
	let cur: *node = lhs;
	for (true) {
		let pf: str = p.cur_file;
		let pl: i32 = p.cur_line;
		let pc: i32 = p.cur_col;
		if (p.cur_kind == TK_LPAREN) {
			advance(p);
			let n: *node = newnode(p.a, N_CALL, pf, pl, pc);
			n.lhs = cur;
			let arghead: *node = nil;
			parsearglist(p, TK_RPAREN, &arghead);
			n.list = arghead;
			expect_tok(p, TK_RPAREN, "expected ')' after args");
			cur = n;
			continue;
		};
		if (p.cur_kind == TK_LBRACK) {
			advance(p);
			// `[ : hi ]` — slice with implicit lo = 0.
			if (p.cur_kind == TK_COLON) {
				advance(p);
				let n: *node = newnode(p.a, N_SLICE, pf, pl, pc);
				n.lhs = cur;
				if (p.cur_kind != TK_RBRACK) {
					n.cond = parseexpr(p);
				};
				expect_tok(p, TK_RBRACK, "expected ']' in slice");
				cur = n;
				continue;
			};
			// Suppress cast inside `[...]` so ':' parses as slice
			// separator rather than the postfix cast operator.
			let prev: i32 = p.nocast;
			p.nocast = 1;
			let e: *node = parseexpr(p);
			p.nocast = prev;
			if (p.cur_kind == TK_COLON) {
				advance(p);
				let n: *node = newnode(p.a, N_SLICE, pf, pl, pc);
				n.lhs = cur;
				n.rhs = e;
				if (p.cur_kind != TK_RBRACK) {
					n.cond = parseexpr(p);
				};
				expect_tok(p, TK_RBRACK, "expected ']' in slice");
				cur = n;
				continue;
			};
			let n: *node = newnode(p.a, N_INDEX, pf, pl, pc);
			n.lhs = cur;
			n.rhs = e;
			expect_tok(p, TK_RBRACK, "expected ']' after index");
			cur = n;
			continue;
		};
		if (p.cur_kind == TK_DOT) {
			advance(p);
			let n: *node = newnode(p.a, N_DOT, pf, pl, pc);
			n.lhs = cur;
			let id: str;
			expectident(p, &id);
			n.str = id;
			cur = n;
			continue;
		};
		if (p.cur_kind == TK_COLON) {
			if (p.nocast != 0) {
				return cur;
			};
			advance(p);
			let n: *node = newnode(p.a, N_CAST, pf, pl, pc);
			n.lhs = cur;
			n.rhs = parsetype(p);
			cur = n;
			continue;
		};
		break;
	};
	return cur;
};

fn parseunary(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	let k: i32 = p.cur_kind;
	if (k == TK_MINUS) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_MINUS; n.lhs = parseunary(p);
		return n;
	};
	if (k == TK_PLUS) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_PLUS; n.lhs = parseunary(p);
		return n;
	};
	if (k == TK_NOT) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_NOT; n.lhs = parseunary(p);
		return n;
	};
	if (k == TK_TILDE) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_TILDE; n.lhs = parseunary(p);
		return n;
	};
	if (k == TK_STAR) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_STAR; n.lhs = parseunary(p);
		return n;
	};
	if (k == TK_AMP) {
		advance(p);
		let n: *node = newnode(p.a, N_UN, pf, pl, pc);
		n.op = TK_AMP; n.lhs = parseunary(p);
		return n;
	};
	return parsepostfix(p, parseprimary(p));
};

fn parsebin(p: *parser, lhs: *node, minp: i32) *node = {
	let cur: *node = lhs;
	for (true) {
		let op: i32 = p.cur_kind;
		let pr: i32 = bprec(op);
		if (pr == 0) { return cur; };
		if (pr < minp) { return cur; };
		let pf: str = p.cur_file;
		let pl: i32 = p.cur_line;
		let pc: i32 = p.cur_col;
		advance(p);
		let rhs: *node = parseunary(p);
		for (true) {
			let np: i32 = bprec(p.cur_kind);
			if (np <= pr) { break; };
			rhs = parsebin(p, rhs, np);
		};
		let n: *node = newnode(p.a, N_BIN, pf, pl, pc);
		n.op = op; n.lhs = cur; n.rhs = rhs;
		cur = n;
	};
	return cur;
};

fn parseexpr(p: *parser) *node = {
	let e: *node = parsebin(p, parseunary(p), 1);
	if (isassignop(p.cur_kind)) {
		let pf: str = p.cur_file;
		let pl: i32 = p.cur_line;
		let pc: i32 = p.cur_col;
		let op: i32 = p.cur_kind;
		advance(p);
		let n: *node = newnode(p.a, N_ASSIGN, pf, pl, pc);
		n.op = op;
		n.lhs = e;
		n.rhs = parseexpr(p);	// right-associative
		return n;
	};
	return e;
};

// ---- statements ------------------------------------------------------
//
// Subset wired today: block, let, return, if (no else-if chain), for
// (single-cond C-style), expr-stmt, defer, break, continue. Switch
// and match arms are not yet wired; tuple-let / multi-let neither.

fn parselet_local(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `let`
	let n: *node = newnode(p.a, N_LET, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	if (accept_tok(p, TK_COLON)) {
		n.lhs = parsetype(p);
	};
	if (accept_tok(p, TK_ASSIGN)) {
		n.rhs = parseexpr(p);
	};
	expect_tok(p, TK_SEMI, "expected ';' after let");
	return n;
};

fn parseblock(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	expect_tok(p, TK_LBRACE, "expected '{' to open block");
	let blk: *node = newnode(p.a, N_BLOCK, pf, pl, pc);
	let head: *node = nil;
	let tail: *node = nil;
	for (p.cur_kind != TK_RBRACE) {
		if (p.cur_kind == TK_EOF) { break; };
		let s: *node = parsestmt(p);
		if (s != nil) {
			if (head == nil) { head = s; tail = s; }
			else { tail.next = s; tail = s; };
		};
	};
	expect_tok(p, TK_RBRACE, "expected '}' to close block");
	blk.list = head;
	return blk;
};

fn parseif(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `if`
	expect_tok(p, TK_LPAREN, "expected '(' after if");
	let n: *node = newnode(p.a, N_IF, pf, pl, pc);
	n.cond = parseexpr(p);
	expect_tok(p, TK_RPAREN, "expected ')' after if condition");
	n.body = parseblock(p);
	if (accept_tok(p, TK_ELSE)) {
		if (p.cur_kind == TK_IF) {
			n.els = parseif(p);
		} else {
			n.els = parseblock(p);
		};
	};
	return n;
};

fn parsefor(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `for`
	expect_tok(p, TK_LPAREN, "expected '(' after for");
	let n: *node = newnode(p.a, N_FOR, pf, pl, pc);
	// Three forms (matching C parser):
	//   for (cond)               — only cond
	//   for (init; cond; post)   — full
	//   for (true)               — infinite (cond is N_TRUE)
	// Distinguish by counting ';'. Look at first chunk: if it's a
	// `let` stmt that's the init. Otherwise, parse expr; if next is
	// ';' it was cond. If we see two ';' total after init, post is
	// next. Simpler: peek for `let` to decide init form.
	if (p.cur_kind == TK_LET) {
		n.lhs = parselet_local(p);	// init (consumes its own ';')
		n.cond = parseexpr(p);
		expect_tok(p, TK_SEMI, "expected ';' after for cond");
		n.rhs = parseexpr(p);
	} else {
		// Parse one expr. If next is ';', it's a 3-clause without init.
		let first: *node = parseexpr(p);
		if (accept_tok(p, TK_SEMI)) {
			// cond ; post
			n.cond = first;
			n.rhs = parseexpr(p);
		} else {
			// just (cond)
			n.cond = first;
		};
	};
	expect_tok(p, TK_RPAREN, "expected ')' after for");
	n.body = parseblock(p);
	return n;
};

fn parsestmt(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;

	// `static` is allowed on local lets per Hare; we accept and skip
	// it (it doesn't change the AST shape).
	if (p.cur_kind == TK_STATIC) { advance(p); };

	if (p.cur_kind == TK_LBRACE) {
		let b: *node = parseblock(p);
		expect_tok(p, TK_SEMI, "expected ';' after block");
		return b;
	};
	if (p.cur_kind == TK_LET)    { return parselet_local(p); };
	if (p.cur_kind == TK_IF) {
		let n: *node = parseif(p);
		expect_tok(p, TK_SEMI, "expected ';' after if");
		return n;
	};
	if (p.cur_kind == TK_FOR) {
		let n: *node = parsefor(p);
		expect_tok(p, TK_SEMI, "expected ';' after for");
		return n;
	};
	if (p.cur_kind == TK_RETURN) {
		advance(p);
		let n: *node = newnode(p.a, N_RETURN, pf, pl, pc);
		if (p.cur_kind != TK_SEMI) {
			let first: *node = parseexpr(p);
			// Hare-style multi-value: `return a, b;` becomes a
			// tuple expression so codegen sees one rvalue.
			if (p.cur_kind == TK_COMMA) {
				let t: *node = newnode(p.a, N_TUPLE, pf, pl, pc);
				t.list = first;
				let tail: *node = first;
				for (accept_tok(p, TK_COMMA)) {
					let e: *node = parseexpr(p);
					tail.next = e;
					tail = e;
				};
				n.lhs = t;
			} else {
				n.lhs = first;
			};
		};
		expect_tok(p, TK_SEMI, "expected ';' after return");
		return n;
	};
	if (p.cur_kind == TK_DEFER) {
		advance(p);
		let n: *node = newnode(p.a, N_DEFER, pf, pl, pc);
		n.lhs = parseexpr(p);
		expect_tok(p, TK_SEMI, "expected ';' after defer");
		return n;
	};
	if (p.cur_kind == TK_BREAK) {
		advance(p);
		expect_tok(p, TK_SEMI, "expected ';' after break");
		return newnode(p.a, N_BREAK, pf, pl, pc);
	};
	if (p.cur_kind == TK_CONTINUE) {
		advance(p);
		expect_tok(p, TK_SEMI, "expected ';' after continue");
		return newnode(p.a, N_CONTINUE, pf, pl, pc);
	};
	// expression statement, or tuple-destructure multi-assign:
	//   a, b = expr;
	// Mirrors cmd/wwc/parse.c:1015-1031. We parse the first lvalue
	// with parseexpr (matches the C side); subsequent lvalues go
	// through parsebin(parseunary, 1) so the `=` stays for us to
	// consume — parseexpr would absorb it.
	let e: *node = parseexpr(p);
	if (p.cur_kind == TK_COMMA) {
		let m: *node = newnode(p.a, N_MASSIGN, pf, pl, pc);
		let head: *node = e;
		let tail: *node = e;
		for (p.cur_kind == TK_COMMA) {
			advance(p);
			let lv: *node = parsebin(p, parseunary(p), 1);
			tail.next = lv;
			tail = lv;
		};
		expect_tok(p, TK_ASSIGN, "expected '=' after multi-assign lvalues");
		m.rhs = parseexpr(p);
		m.list = head;
		expect_tok(p, TK_SEMI, "expected ';' after multi-assign");
		return m;
	};
	let n: *node = newnode(p.a, N_EXPRSTMT, pf, pl, pc);
	n.lhs = e;
	expect_tok(p, TK_SEMI, "expected ';' after expression statement");
	return n;
};

// ---- top-level decl parsers ------------------------------------------

fn parseuse(p: *parser) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `use`
	let n: *node = newnode(p.a, N_USE, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	expect_tok(p, TK_SEMI, "expected ';' after use");
	return n;
};

fn parsedef(p: *parser, exported: i32) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `def`
	let n: *node = newnode(p.a, N_DEF, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	expect_tok(p, TK_COLON, "expected ':' in def");
	n.lhs = parsetype(p);
	expect_tok(p, TK_ASSIGN, "expected '=' in def");
	n.rhs = parseexpr(p);
	expect_tok(p, TK_SEMI, "expected ';' after def");
	n.exported = exported;
	return n;
};

fn parselet(p: *parser, exported: i32) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `let`
	let n: *node = newnode(p.a, N_LET, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	if (accept_tok(p, TK_COLON)) {
		n.lhs = parsetype(p);
	};
	if (accept_tok(p, TK_ASSIGN)) {
		n.rhs = parseexpr(p);
	};
	expect_tok(p, TK_SEMI, "expected ';' after let");
	n.exported = exported;
	return n;
};

fn parseattrs(p: *parser) *node = {
	let head: *node = nil;
	let tail: *node = nil;
	for (p.cur_kind == TK_AT) {
		let pf: str = p.cur_file;
		let pl: i32 = p.cur_line;
		let pc: i32 = p.cur_col;
		advance(p);
		let a: *node = newnode(p.a, N_ATTR, pf, pl, pc);
		let id: str;
		expectident(p, &id);
		a.str = id;
		expect_tok(p, TK_LPAREN, "expected '(' after attribute name");
		let arghead: *node = nil;
		parsearglist(p, TK_RPAREN, &arghead);
		a.list = arghead;
		expect_tok(p, TK_RPAREN, "expected ')' after attribute args");
		if (head == nil) { head = a; tail = a; }
		else { tail.next = a; tail = a; };
	};
	return head;
};

fn parseparams(p: *parser) *node = {
	if (p.cur_kind == TK_RPAREN) { return nil; };
	let head: *node = nil;
	let tail: *node = nil;
	for (true) {
		let pf: str = p.cur_file;
		let pl: i32 = p.cur_line;
		let pc: i32 = p.cur_col;
		let n: *node = newnode(p.a, N_PARAM, pf, pl, pc);
		// Param form: IDENT ':' type. Anonymous-type-only params (used
		// in fn type expressions) aren't yet wired here.
		let id: str;
		expectident(p, &id);
		n.str = id;
		expect_tok(p, TK_COLON, "expected ':' in parameter");
		n.lhs = parsetype(p);
		if (head == nil) { head = n; tail = n; }
		else { tail.next = n; tail = n; };
		if (!accept_tok(p, TK_COMMA)) { break; };
		if (p.cur_kind == TK_RPAREN) { break; };
	};
	return head;
};

fn parsefn(p: *parser, exported: i32, attrs: *node) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `fn`
	let n: *node = newnode(p.a, N_FNDECL, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	expect_tok(p, TK_LPAREN, "expected '(' after fn name");
	n.list = parseparams(p);
	expect_tok(p, TK_RPAREN, "expected ')' after params");
	if (p.cur_kind != TK_ASSIGN) {
		if (p.cur_kind != TK_SEMI) {
			n.lhs = parsetype(p);
		};
	};
	if (accept_tok(p, TK_ASSIGN)) {
		n.body = parseblock(p);
		expect_tok(p, TK_SEMI, "expected ';' after fn body");
	} else {
		// Body-less fn: FFI declaration (`fn name(args) ret;`).
		expect_tok(p, TK_SEMI, "expected ';' after fn header");
	};
	n.exported = exported;
	n.attr = attrs;
	return n;
};

fn parsetypedecl(p: *parser, exported: i32) *node = {
	let pf: str = p.cur_file;
	let pl: i32 = p.cur_line;
	let pc: i32 = p.cur_col;
	advance(p);	// past `type`
	let n: *node = newnode(p.a, N_TYPEDECL, pf, pl, pc);
	let id: str;
	expectident(p, &id);
	n.str = id;
	expect_tok(p, TK_ASSIGN, "expected '=' in type decl");
	n.lhs = parsetype(p);
	expect_tok(p, TK_SEMI, "expected ';' after type decl");
	n.exported = exported;
	return n;
};

// ---- file-level loop -------------------------------------------------

export fn parsefile(p: *parser) *node = {
	let f: *node = newnode(p.a, N_FILE, p.cur_file, p.cur_line, p.cur_col);
	let head: *node = nil;
	let tail: *node = nil;

	for (p.cur_kind != TK_EOF) {
		let attrs: *node = parseattrs(p);
		let exported: i32 = 0;
		if (p.cur_kind == TK_EXPORT) { exported = 1; advance(p); };

		let d: *node = nil;
		if (p.cur_kind == TK_USE) {
			d = parseuse(p);
		} else { if (p.cur_kind == TK_DEF) {
			d = parsedef(p, exported);
		} else { if (p.cur_kind == TK_TYPE) {
			d = parsetypedecl(p, exported);
		} else { if (p.cur_kind == TK_LET) {
			d = parselet(p, exported);
		} else { if (p.cur_kind == TK_FN) {
			d = parsefn(p, exported, attrs);
		} else {
			// Recovery: chew tokens until next ';' or EOF, balancing
			// '{' '}' pairs so internal ';'s in unfamiliar forms don't
			// derail us.
			for (p.cur_kind != TK_SEMI) {
				if (p.cur_kind == TK_EOF) { break; };
				if (p.cur_kind == TK_LBRACE) {
					let depth: i32 = 0;
					for (true) {
						if (p.cur_kind == TK_EOF) { break; };
						if (p.cur_kind == TK_LBRACE) { depth += 1; advance(p); continue; };
						if (p.cur_kind == TK_RBRACE) {
							depth -= 1;
							advance(p);
							if (depth == 0) { break; };
							continue;
						};
						advance(p);
					};
					continue;
				};
				advance(p);
			};
			if (p.cur_kind == TK_SEMI) { advance(p); };
		};};};};};

		if (d != nil) {
			if (head == nil) {
				head = d;
				tail = d;
			} else {
				tail.next = d;
				tail = d;
			};
		};
	};
	f.list = head;
	return f;
};

// selfhost/cmd/wwc/type.ww — port of cmd/wwc/type.c.
//
// Status: full structural port. The C version uses module-globals for
// the primitive types (ty_void, ty_i32, …); ww doesn't have writable
// global storage yet, so we bundle the primitives into a `tctx` that
// the checker passes around explicitly. typesinit fills the tctx
// once per arena.

use os;
use mem;

// ---- TypeKind ---------------------------------------------------------
// Numeric values must stay aligned with cmd/wwc/ww.h TypeKind so the
// next diff signal (typed-AST printer / cgen) can compare across the
// two implementations.

def TY_NONE:     i32 = 0;
def TY_VOID:     i32 = 1;
def TY_BOOL:     i32 = 2;
def TY_RUNE:     i32 = 3;
def TY_I8:       i32 = 4;
def TY_I16:      i32 = 5;
def TY_I32:      i32 = 6;
def TY_I64:      i32 = 7;
def TY_U8:       i32 = 8;
def TY_U16:      i32 = 9;
def TY_U32:      i32 = 10;
def TY_U64:      i32 = 11;
def TY_UINT:     i32 = 12;
def TY_INT:      i32 = 13;
def TY_UINTPTR:  i32 = 14;
def TY_F32:      i32 = 15;
def TY_F64:      i32 = 16;
def TY_STR:      i32 = 17;
def TY_PTR:      i32 = 18;
def TY_SLICE:    i32 = 19;
def TY_ARRAY:    i32 = 20;
def TY_STRUCT:   i32 = 21;
def TY_FN:       i32 = 22;
def TY_CHAN:     i32 = 23;
def TY_NAMED:    i32 = 24;
def TY_TUPLE:    i32 = 25;
def TY_TAGGED:   i32 = 26;
def TY_ERR:      i32 = 27;
def TY_UNTYPED_INT:   i32 = 28;
def TY_UNTYPED_FLOAT: i32 = 29;
def TY_UNTYPED_STR:   i32 = 30;
def TY_UNTYPED_RUNE:  i32 = 31;
def TY_UNTYPED_BOOL:  i32 = 32;
def TY_UNTYPED_NIL:   i32 = 33;

// ---- tinfo / tfield / tparam -----------------------------------------

type tfield = struct {
	name:   str,
	type_:  *tinfo,
	offset: u64,
	tnext:  *tfield,
};

type tparam = struct {
	name:   str,
	type_:  *tinfo,
	tnext:  *tparam,
};

type tinfo = struct {
	kind:     i32,
	size:     u64,
	align:    u64,
	sub:      *tinfo,	// ptr/slice/array/chan element
	alen:     u64,
	fields:   *tfield,
	params:   *tparam,
	ret:      *tinfo,
	variadic: i32,
	name:     str,
	under:    *tinfo,
};

// ---- tctx — the box of primitive types -------------------------------

type tctx = struct {
	a:        *arena,
	ty_void:  *tinfo,
	ty_bool:  *tinfo,
	ty_rune:  *tinfo,
	ty_i8:    *tinfo,
	ty_i16:   *tinfo,
	ty_i32:   *tinfo,
	ty_i64:   *tinfo,
	ty_u8:    *tinfo,
	ty_u16:   *tinfo,
	ty_u32:   *tinfo,
	ty_u64:   *tinfo,
	ty_int:   *tinfo,
	ty_uint:  *tinfo,
	ty_uintptr: *tinfo,
	ty_f32:   *tinfo,
	ty_f64:   *tinfo,
	ty_str:   *tinfo,
	ty_err:   *tinfo,
	ty_untyped_int:   *tinfo,
	ty_untyped_float: *tinfo,
	ty_untyped_str:   *tinfo,
	ty_untyped_rune:  *tinfo,
	ty_untyped_bool:  *tinfo,
	ty_untyped_nil:   *tinfo,
};

// ---- constructors -----------------------------------------------------

export fn newtype(a: *arena, k: i32) *tinfo = {
	let t: *tinfo = amalloc(a, 96u64): *tinfo;
	t.kind = k;
	return t;
};

fn prim(a: *arena, k: i32, nm: str, sz: u64, al: u64) *tinfo = {
	let t: *tinfo = newtype(a, k);
	t.name = nm;
	t.size = sz;
	if (al > 0u64) { t.align = al; } else { t.align = sz; };
	return t;
};

export fn typesinit(c: *tctx, a: *arena) void = {
	c.a = a;
	c.ty_void   = prim(a, TY_VOID, "void",  0u64, 1u64);
	c.ty_bool   = prim(a, TY_BOOL, "bool",  1u64, 1u64);
	c.ty_rune   = prim(a, TY_RUNE, "rune",  4u64, 4u64);
	c.ty_i8     = prim(a, TY_I8,   "i8",    1u64, 1u64);
	c.ty_i16    = prim(a, TY_I16,  "i16",   2u64, 2u64);
	c.ty_i32    = prim(a, TY_I32,  "i32",   4u64, 4u64);
	c.ty_i64    = prim(a, TY_I64,  "i64",   8u64, 8u64);
	c.ty_u8     = prim(a, TY_U8,   "u8",    1u64, 1u64);
	c.ty_u16    = prim(a, TY_U16,  "u16",   2u64, 2u64);
	c.ty_u32    = prim(a, TY_U32,  "u32",   4u64, 4u64);
	c.ty_u64    = prim(a, TY_U64,  "u64",   8u64, 8u64);
	c.ty_int    = prim(a, TY_INT,  "int",   8u64, 8u64);
	c.ty_uint   = prim(a, TY_UINT, "uint",  8u64, 8u64);
	c.ty_uintptr= prim(a, TY_UINTPTR, "uintptr", 8u64, 8u64);
	c.ty_f32    = prim(a, TY_F32,  "f32",   4u64, 4u64);
	c.ty_f64    = prim(a, TY_F64,  "f64",   8u64, 8u64);
	c.ty_str    = prim(a, TY_STR,  "str",  16u64, 8u64);
	c.ty_err    = prim(a, TY_ERR,  "<err>", 0u64, 1u64);

	c.ty_untyped_int   = prim(a, TY_UNTYPED_INT,   "untyped_int",   0u64, 1u64);
	c.ty_untyped_float = prim(a, TY_UNTYPED_FLOAT, "untyped_float", 0u64, 1u64);
	c.ty_untyped_str   = prim(a, TY_UNTYPED_STR,   "untyped_str",   0u64, 1u64);
	c.ty_untyped_rune  = prim(a, TY_UNTYPED_RUNE,  "untyped_rune",  0u64, 1u64);
	c.ty_untyped_bool  = prim(a, TY_UNTYPED_BOOL,  "untyped_bool",  0u64, 1u64);
	c.ty_untyped_nil   = prim(a, TY_UNTYPED_NIL,   "untyped_nil",   0u64, 1u64);
};

export fn type_ptr(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_PTR);
	t.sub = sub;
	t.size = 8u64;
	t.align = 8u64;
	return t;
};

export fn type_slice(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_SLICE);
	t.sub = sub;
	t.size = 24u64;
	t.align = 8u64;
	return t;
};

export fn type_array(a: *arena, sub: *tinfo, n: u64) *tinfo = {
	let t: *tinfo = newtype(a, TY_ARRAY);
	t.sub = sub;
	t.alen = n;
	if (sub != nil) {
		t.size = sub.size * n;
		t.align = sub.align;
	} else {
		t.align = 1u64;
	};
	return t;
};

export fn type_chan(a: *arena, sub: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_CHAN);
	t.sub = sub;
	t.size = 8u64;
	t.align = 8u64;
	return t;
};

export fn type_named(a: *arena, name: str, under: *tinfo) *tinfo = {
	let t: *tinfo = newtype(a, TY_NAMED);
	t.name = name;
	t.under = under;
	if (under != nil) {
		t.size = under.size;
		t.align = under.align;
	};
	return t;
};

// ---- predicates -------------------------------------------------------

export fn type_isint(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_I8)  { return true; };
	if (k == TY_I16) { return true; };
	if (k == TY_I32) { return true; };
	if (k == TY_I64) { return true; };
	if (k == TY_U8)  { return true; };
	if (k == TY_U16) { return true; };
	if (k == TY_U32) { return true; };
	if (k == TY_U64) { return true; };
	if (k == TY_INT) { return true; };
	if (k == TY_UINT){ return true; };
	if (k == TY_UINTPTR) { return true; };
	if (k == TY_RUNE){ return true; };
	if (k == TY_UNTYPED_INT)  { return true; };
	if (k == TY_UNTYPED_RUNE) { return true; };
	if (k == TY_NAMED) { return type_isint(t.under); };
	return false;
};

export fn type_isfloat(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_F32) { return true; };
	if (k == TY_F64) { return true; };
	if (k == TY_UNTYPED_FLOAT) { return true; };
	if (k == TY_NAMED) { return type_isfloat(t.under); };
	return false;
};

export fn type_isnum(t: *tinfo) bool = {
	if (type_isint(t)) { return true; };
	return type_isfloat(t);
};

export fn type_isunsigned(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_U8)  { return true; };
	if (k == TY_U16) { return true; };
	if (k == TY_U32) { return true; };
	if (k == TY_U64) { return true; };
	if (k == TY_UINT){ return true; };
	if (k == TY_UINTPTR) { return true; };
	if (k == TY_NAMED) { return type_isunsigned(t.under); };
	return false;
};

export fn type_isuntyped(t: *tinfo) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == TY_UNTYPED_INT)   { return true; };
	if (k == TY_UNTYPED_FLOAT) { return true; };
	if (k == TY_UNTYPED_STR)   { return true; };
	if (k == TY_UNTYPED_RUNE)  { return true; };
	if (k == TY_UNTYPED_BOOL)  { return true; };
	if (k == TY_UNTYPED_NIL)   { return true; };
	return false;
};

// type_eq — structural equality. Named types compare nominally.
export fn type_eq(a: *tinfo, b: *tinfo) bool = {
	if (a == b) { return true; };
	if (a == nil) { return false; };
	if (b == nil) { return false; };
	if (a.kind != b.kind) { return false; };
	let k: i32 = a.kind;
	if (k == TY_PTR)   { return type_eq(a.sub, b.sub); };
	if (k == TY_SLICE) { return type_eq(a.sub, b.sub); };
	if (k == TY_CHAN)  { return type_eq(a.sub, b.sub); };
	if (k == TY_ARRAY) {
		if (a.alen != b.alen) { return false; };
		return type_eq(a.sub, b.sub);
	};
	if (k == TY_FN) {
		if (a.variadic != b.variadic) { return false; };
		if (!type_eq(a.ret, b.ret))   { return false; };
		let pa: *tparam = a.params;
		let pb: *tparam = b.params;
		for (true) {
			if (pa == nil) { if (pb == nil) { return true; }; return false; };
			if (pb == nil) { return false; };
			if (!type_eq(pa.type_, pb.type_)) { return false; };
			pa = pa.tnext;
			pb = pb.tnext;
		};
		return true;
	};
	if (k == TY_STRUCT) {
		let fa: *tfield = a.fields;
		let fb: *tfield = b.fields;
		for (true) {
			if (fa == nil) { if (fb == nil) { return true; }; return false; };
			if (fb == nil) { return false; };
			let na: str = fa.name;
			let nb: str = fb.name;
			if (na.len != nb.len) { return false; };
			let i: i32 = 0;
			for (i < na.len) {
				if (na[i] != nb[i]) { return false; };
				i += 1;
			};
			if (!type_eq(fa.type_, fb.type_)) { return false; };
			fa = fa.tnext;
			fb = fb.tnext;
		};
		return true;
	};
	if (k == TY_NAMED) { return false; };	// nominal: only same ptr
	if (k == TY_TUPLE) {
		let pa: *tparam = a.params;
		let pb: *tparam = b.params;
		for (true) {
			if (pa == nil) { if (pb == nil) { return true; }; return false; };
			if (pb == nil) { return false; };
			if (!type_eq(pa.type_, pb.type_)) { return false; };
			pa = pa.tnext;
			pb = pb.tnext;
		};
		return true;
	};
	return true;	// primitives match by kind alone
};

// selfhost/cmd/wwc/sym.ww — port of cmd/wwc/sym.c.
//
// Per-scope hashtable, chained to the parent. Lookup walks up.
// Plan 9 / Hare flavoured. Duplicate definitions in the same scope
// return nil; the caller flags the error.

use mem;
use typ;
use ast;

// Symbol kinds — must stay numerically aligned with cmd/wwc/ww.h Skind.
def SK_NONE:  i32 = 0;
def SK_VAR:   i32 = 1;
def SK_PARAM: i32 = 2;
def SK_DEF:   i32 = 3;
def SK_TYPE:  i32 = 4;
def SK_FN:    i32 = 5;
def SK_USE:   i32 = 6;
def SK_FIELD: i32 = 7;

type sym = struct {
	name:     str,
	skind:    i32,
	type_:    *tinfo,
	decl:     *node,
	exported: i32,
	snext:    *sym,	// iteration order
	hashnext: *sym,	// hash bucket chain
	scope:    *scope,
};

def NBUCKETS: i32 = 16;

type scope = struct {
	parent:   *scope,
	first:    *sym,
	last:     *sym,
	buckets:  **sym,	// length = NBUCKETS
	nbuckets: i32,
	a:        *arena,
};

// FNV-1a 64 — same hash the C side uses, so bucket distribution is
// identical when both walk a scope in declaration order.
fn hashstr(s: str) u64 = {
	let h: u64 = 14695981039346656037u64;
	let i: i32 = 0;
	for (i < s.len) {
		let c: u8 = s[i];
		h = h ^ (c: u64);
		h = h * 1099511628211u64;
		i += 1;
	};
	return h;
};

export fn newscope(a: *arena, parent: *scope) *scope = {
	let s: *scope = amalloc(a, 64u64): *scope;
	s.parent = parent;
	s.a = a;
	s.nbuckets = NBUCKETS;
	s.buckets = amalloc(a, (NBUCKETS: u64) * 8u64): **sym;
	return s;
};

export fn streq(a: str, b: str) bool = {
	if (a.len != b.len) { return false; };
	let i: i32 = 0;
	for (i < a.len) {
		if (a[i] != b[i]) { return false; };
		i += 1;
	};
	return true;
};

export fn scope_lookup_local(s: *scope, name: str) *sym = {
	if (s == nil) { return nil; };
	let h: u64 = hashstr(name);
	let bi: i32 = (h % (s.nbuckets: u64)): i32;
	let b: *sym = s.buckets[bi];
	for (b != nil) {
		let bn: str = b.name;
		if (streq(bn, name)) { return b; };
		b = b.hashnext;
	};
	return nil;
};

export fn scope_lookup(s: *scope, name: str) *sym = {
	for (s != nil) {
		let r: *sym = scope_lookup_local(s, name);
		if (r != nil) { return r; };
		s = s.parent;
	};
	return nil;
};

export fn scope_define(s: *scope, name: str, k: i32, t: *tinfo, decl: *node) *sym = {
	if (scope_lookup_local(s, name) != nil) { return nil; };
	let sy: *sym = amalloc(s.a, 80u64): *sym;
	sy.name = name;
	sy.skind = k;
	sy.type_ = t;
	sy.decl = decl;
	sy.scope = s;
	let h: u64 = hashstr(name);
	let bi: i32 = (h % (s.nbuckets: u64)): i32;
	sy.hashnext = s.buckets[bi];
	s.buckets[bi] = sy;
	if (s.first == nil) { s.first = sy; } else { s.last.snext = sy; };
	s.last = sy;
	return sy;
};

// selfhost/cmd/wwc/check.ww — minimal port of cmd/wwc/check.c.
//
// Status: name-resolution + primitive-type seeding only. Full type
// inference, conversion rules, tagged-union dispatch typing, return-
// type checking, etc. all live in cmd/wwc/check.c (937 lines) and
// will land here in subsequent commits.
//
// What this version does:
//   1. Creates a top scope and seeds it with primitive type names so
//      `i32`, `str`, `*u8` etc. resolve.
//   2. Walks the file's top-level decls (use/def/type/fn/let) and
//      installs Sym entries for each.
//   3. Recursively walks fn bodies; for every N_IDENT used as an
//      expression or as a type name, looks it up and counts the
//      resolved vs. unresolved.
//   4. Returns a summary the caller (wwdump -r) prints; the test
//      asserts unresolved == 0 on every selfhost fixture, which is
//      the floor signal that the frontend can name-resolve real ww.

use os;
use mem;
use tok;

type checker = struct {
	a:        *arena,
	tc:       *tctx,
	top:      *scope,
	cur:      *scope,
	nresolved:   i32,
	nunresolved: i32,
	errs:        i32,
	verbose:     i32,	// when non-zero, log each unresolved name
};

// seed_primitives — install the built-in type names so `i32`, `str`,
// etc. can be looked up like ordinary symbols.
fn seed_primitives(c: *checker) void = {
	scope_define(c.top, "void",    SK_TYPE, c.tc.ty_void,    nil);
	scope_define(c.top, "bool",    SK_TYPE, c.tc.ty_bool,    nil);
	scope_define(c.top, "rune",    SK_TYPE, c.tc.ty_rune,    nil);
	scope_define(c.top, "i8",      SK_TYPE, c.tc.ty_i8,      nil);
	scope_define(c.top, "i16",     SK_TYPE, c.tc.ty_i16,     nil);
	scope_define(c.top, "i32",     SK_TYPE, c.tc.ty_i32,     nil);
	scope_define(c.top, "i64",     SK_TYPE, c.tc.ty_i64,     nil);
	scope_define(c.top, "u8",      SK_TYPE, c.tc.ty_u8,      nil);
	scope_define(c.top, "u16",     SK_TYPE, c.tc.ty_u16,     nil);
	scope_define(c.top, "u32",     SK_TYPE, c.tc.ty_u32,     nil);
	scope_define(c.top, "u64",     SK_TYPE, c.tc.ty_u64,     nil);
	scope_define(c.top, "int",     SK_TYPE, c.tc.ty_int,     nil);
	scope_define(c.top, "uint",    SK_TYPE, c.tc.ty_uint,    nil);
	scope_define(c.top, "uintptr", SK_TYPE, c.tc.ty_uintptr, nil);
	scope_define(c.top, "f32",     SK_TYPE, c.tc.ty_f32,     nil);
	scope_define(c.top, "f64",     SK_TYPE, c.tc.ty_f64,     nil);
	scope_define(c.top, "str",     SK_TYPE, c.tc.ty_str,     nil);
	// `nil`, `true`, `false` are keywords — handled at the lex/parser
	// level, no symbol needed.
	// `len`, `alloc`, `free` are pseudo-builtins; scope_define them so
	// their use sites resolve. The actual semantics live in cgen.
	scope_define(c.top, "len",   SK_FN, nil, nil);
	scope_define(c.top, "alloc", SK_FN, nil, nil);
	scope_define(c.top, "free",  SK_FN, nil, nil);
};

// install_decl — install the top-level decl's name into the top scope.
// We don't compute its type yet (that's the resolve pass) — just bind
// the name so forward references resolve.
fn install_decl(c: *checker, d: *node) void = {
	if (d == nil) { return; };
	let k: i32 = d.kind;
	let nm: str = d.str;
	if (k == N_USE)      { scope_define(c.top, nm, SK_USE,  nil, d); return; };
	if (k == N_DEF)      { scope_define(c.top, nm, SK_DEF,  nil, d); return; };
	if (k == N_TYPEDECL) { scope_define(c.top, nm, SK_TYPE, nil, d); return; };
	if (k == N_FNDECL)   { scope_define(c.top, nm, SK_FN,   nil, d); return; };
	if (k == N_LET)      { scope_define(c.top, nm, SK_VAR,  nil, d); return; };
};

// resolve_walk — recursive AST walk that, for every N_IDENT and
// N_TNAME seen, looks up the name and bumps the resolved/unresolved
// counters. Local lets are installed in the current scope as soon as
// their init/type expressions have been walked (forward use of a let
// before its declaration would resolve to nothing — same semantics as
// the C checker's collect-then-resolve flow within a function).
fn resolve_walk(c: *checker, n: *node) void = {
	if (n == nil) { return; };
	let k: i32 = n.kind;

	// `use IDENT;` — name is a module label, not a free ident.
	if (k == N_USE) { return; };

	if (k == N_IDENT) {
		let nm: str = n.str;
		if (nm.len > 0) {
			let s: *sym = scope_lookup(c.cur, nm);
			if (s == nil) {
				c.nunresolved += 1;
				if (c.verbose != 0) {
					os.write(2, "  unresolved id: ".ptr, 17u64);
					os.write(2, nm.ptr, nm.len: u64);
					os.write(2, "\n".ptr, 1u64);
				};
			} else { c.nresolved += 1; };
		};
	};

	if (k == N_TNAME) {
		let nm: str = n.str;
		if (nm.len > 0) {
			let s: *sym = scope_lookup(c.cur, nm);
			if (s == nil) {
				c.nunresolved += 1;
				if (c.verbose != 0) {
					os.write(2, "  unresolved tname: ".ptr, 20u64);
					os.write(2, nm.ptr, nm.len: u64);
					os.write(2, "\n".ptr, 1u64);
				};
			} else { c.nresolved += 1; };
		};
	};

	// `match (e) { case let v: T => stmt; ... }` — the binding `v`
	// is declared by the case arm and visible inside its body.
	if (k == N_MCASE) {
		if (n.lhs  != nil) { resolve_walk(c, n.lhs);  };
		let nm: str = n.str;
		if (nm.len > 0) {
			scope_define(c.cur, nm, SK_VAR, nil, n);
		};
		if (n.body != nil) { resolve_walk(c, n.body); };
		return;
	};

	if (k == N_DOT) {
		// Walk only the base; the .field name is a member, not a
		// free identifier.
		if (n.lhs != nil) { resolve_walk(c, n.lhs); };
		return;
	};

	if (k == N_FIELD) {
		if (n.lhs != nil) { resolve_walk(c, n.lhs); };
		return;
	};

	if (k == N_TFIELD) {
		if (n.lhs != nil) { resolve_walk(c, n.lhs); };
		return;
	};

	// Walk children (mirroring ast.ww's printer descent order).
	if (n.attr != nil) { resolve_walk(c, n.attr); };
	if (n.lhs  != nil) { resolve_walk(c, n.lhs);  };
	if (n.rhs  != nil) { resolve_walk(c, n.rhs);  };
	if (n.cond != nil) { resolve_walk(c, n.cond); };
	if (n.body != nil) { resolve_walk(c, n.body); };
	if (n.els  != nil) { resolve_walk(c, n.els);  };
	if (n.list != nil) {
		let m: *node = n.list;
		for (m != nil) {
			resolve_walk(c, m);
			m = m.next;
		};
	};

	// After walking children: a local `let X: T = init;` registers
	// `X` so subsequent statements can resolve it. Top-level lets
	// are installed in install_decl, so this duplicate install at
	// the file scope just no-ops (scope_define returns nil on dup).
	if (k == N_LET) {
		let nm: str = n.str;
		if (nm.len > 0) {
			scope_define(c.cur, nm, SK_VAR, nil, n);
		};
	};
};

// install_param — when entering a fn body, define its params in a
// fresh local scope.
fn install_params(c: *checker, params: *node) void = {
	let p: *node = params;
	for (p != nil) {
		if (p.kind == N_PARAM) {
			let nm: str = p.str;
			if (nm.len > 0) {
				scope_define(c.cur, nm, SK_PARAM, nil, p);
			};
		};
		p = p.next;
	};
};

// resolve_fnbody — open a child scope for the fn, install its params,
// then walk the body. Local lets installed by walk_stmt (a future
// extension); for the current pass we just resolve-walk without
// per-statement scopes.
fn resolve_fnbody(c: *checker, fnnode: *node) void = {
	let outer: *scope = c.cur;
	c.cur = newscope(c.a, c.cur);
	install_params(c, fnnode.list);
	if (fnnode.body != nil) {
		resolve_walk(c, fnnode.body);
	};
	c.cur = outer;
};

export fn check_init(c: *checker, a: *arena, tc: *tctx) void = {
	c.a = a;
	c.tc = tc;
	c.top = newscope(a, nil);
	c.cur = c.top;
	c.nresolved = 0;
	c.nunresolved = 0;
	c.errs = 0;
	c.verbose = 0;
	seed_primitives(c);
};

export fn check_file(c: *checker, file: *node) void = {
	if (file == nil) { return; };
	if (file.kind != N_FILE) { return; };

	// Pass 1: install all top-level names.
	let d: *node = file.list;
	for (d != nil) {
		install_decl(c, d);
		d = d.next;
	};

	// Pass 2: walk decl bodies/types and resolve identifiers.
	d = file.list;
	for (d != nil) {
		let k: i32 = d.kind;
		if (k == N_FNDECL) {
			if (d.lhs != nil) { resolve_walk(c, d.lhs); };	// return type
			resolve_fnbody(c, d);
		} else { if (k == N_DEF) {
			if (d.lhs != nil) { resolve_walk(c, d.lhs); };
			if (d.rhs != nil) { resolve_walk(c, d.rhs); };
		} else { if (k == N_TYPEDECL) {
			if (d.lhs != nil) { resolve_walk(c, d.lhs); };
		} else { if (k == N_LET) {
			if (d.lhs != nil) { resolve_walk(c, d.lhs); };
			if (d.rhs != nil) { resolve_walk(c, d.rhs); };
		};};};};
		d = d.next;
	};
};

// selfhost/cmd/wwc/cgen.ww — port of cmd/6c/cgen.c.
//
// Status: GROWING. Each subsystem we add is verified by `wwdump_ww -c`
// producing byte-identical output to C-side `6c` for the same source,
// then by assembling + linking + running the result.
//
// Current coverage:
//   - decls:  N_FILE, N_FNDECL (params, frame for locals, prologue
//             + dual-epilogue suppression; FFI body-less fn skipped)
//   - stmts:  N_BLOCK, N_RETURN, N_EXPRSTMT, N_LET (no init),
//             N_LET (int-literal / ident / call / N_BIN init),
//             N_IF (with optional else), N_FOR (cond-only and full
//             init/cond/post), N_BREAK, N_CONTINUE
//   - exprs:  N_INTLIT, N_IDENT (local/param), N_BIN with full op
//             coverage (+/-/*/// %, &/|/^, <</>>, comparisons with
//             signed-vs-unsigned dispatch, &&/||), N_UN (- ! ~ &amp; *),
//             N_CALL (recursive R-to-L push, pop into argregs L-to-R),
//             N_ASSIGN to local idents (plain and compound +=/-=)
//
// Type info is shallow — frame slots are 8 bytes per local, all loads
// /stores are MOVQ. Programs that mix i8/i32/i64 locals work but spill
// 8 bytes per local. Float, str, slice, struct, match, defer, alloc,
// tagged-union return — none of those are wired yet.

use os;
use mem;
use ast;
use tok;
use typ;
use sym;
use strconv;

// ---- typedef alias registry -----------------------------------------
//
// `type error = str;` makes `error` a struct-shape alias. We track
// alias→target so is_str_type / is_slice_type / struct_lookup can
// resolve through the chain. Only direct N_TNAME aliases are mapped;
// `type p = struct {...}` is handled by collect_structs.

type alias_ent = struct {
	aname:   str,
	target:  *node,	// the rhs type expr
	aanext:  *alias_ent,
};

fn collect_aliases(c: *cgen, file: *node) void = {
	c.aliases = nil;
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_TYPEDECL) {
			let body: *node = d.lhs;
			if (body != nil) {
				if (body.kind != N_TSTRUCT) {
					let a: *alias_ent = amalloc(c.a, 32u64): *alias_ent;
					a.aname = d.str;
					a.target = body;
					a.aanext = c.aliases;
					c.aliases = a;
				};
			};
		};
		d = d.next;
	};
};

fn alias_lookup(c: *cgen, name: str) *node = {
	let a: *alias_ent = c.aliases;
	for (a != nil) {
		let an: str = a.aname;
		if (streq(an, name)) { return a.target; };
		a = a.aanext;
	};
	return nil;
};

// resolve_type — follow typedef alias chains to a "canonical" type
// expr (str/slice/array/struct/...). Stops on cycles via depth limit.
fn resolve_type(c: *cgen, t: *node) *node = {
	let cur: *node = t;
	let depth: i32 = 0;
	for (depth < 16) {
		if (cur == nil) { return nil; };
		if (cur.kind != N_TNAME) { return cur; };
		let nm: str = cur.str;
		let next: *node = alias_lookup(c, nm);
		if (next == nil) { return cur; };
		cur = next;
		depth += 1;
	};
	return cur;
};

// ---- struct registry ------------------------------------------------
//
// Per-file map from struct name → list of fields with computed offsets
// and sizes. Built when cg_file walks N_TYPEDECL with N_TSTRUCT lhs.
// N_DOT and N_ASSIGN consult this to resolve `s.field` for struct or
// *struct bases.

type field_info = struct {
	fname: str,
	foff:  i32,
	fsz:   i32,
	tnode: *node,	// the field type expr, for nested struct lookups
	finext: *field_info,
};

type struct_info = struct {
	sname:    str,
	fields:   *field_info,
	tot_size: i32,
	sinext:   *struct_info,
};

// ---- locals / frame --------------------------------------------------

type local = struct {
	name:  str,
	off:   i32,
	tnode: *node,	// declared type expr (N_TNAME / N_TPTR / ...) or nil
	lnext: *local,
};

// strlit — interned string literal record. Emitted as a DATA directive
// after all functions; cgexpr N_STRLIT loads (LEAQ ptr, MOVQ len).
type strlit = struct {
	label: str,	// "_S_<seq>"
	bytes: str,
	slnext: *strlit,
};

// ffi — `@symbol("name")` mapping. Body-less fn `foo` with this attr
// gets its CALL target rewritten to `name`.
type ffi = struct {
	ident:  str,
	symbol: str,
	fnext:  *ffi,
};

def LOOP_MAX: i32 = 16;

type cgen = struct {
	a:        *arena,
	locals:   *local,
	frame:    i32,
	last_was_return: i32,
	labelseq: i32,
	strlit_seq: i32,
	strlits: *strlit,
	ffis:    *ffi,
	defs:    *def_ent,
	fnrets:  *fnret,
	aliases: *alias_ent,
	structs: *struct_info,
	fn_name:  str,
	fn_ret:   *node,	// declared return type of current fn (or nil)
	loop_top: i32,
	loop_end_buf:  *str,	// stack of end labels for break
	loop_cont_buf: *str,	// stack of cont labels for continue
};

fn cgen_init(c: *cgen, a: *arena) void = {
	c.a = a;
	c.locals = nil;
	c.frame = 0;
	c.last_was_return = 0;
	c.labelseq = 0;
	// Note: strlit_seq, strlits, ffis are *not* reset here; they
	// persist across cgfn calls within one file. cg_file resets them
	// at the start of each compilation unit.
	c.loop_top = 0;
	c.loop_end_buf  = amalloc(a, (LOOP_MAX: u64) * 16u64): *str;
	c.loop_cont_buf = amalloc(a, (LOOP_MAX: u64) * 16u64): *str;
};

// local_alloc — append a slot for `name` without dedup. Used for
// match-arm bindings, which C cgen allocates via cgexpr's by-value
// `locals` list — so two separate matches each get fresh slots even
// when their bind names collide. scan_locals follows the same rule
// for N_MCASE.
fn local_alloc(c: *cgen, name: str, sz: i32, tnode: *node) i32 = {
	let asz: i32 = sz;
	if (asz < 8) { asz = 8; };
	if ((asz & 7) != 0) { asz = (asz + 7) & ~7; };
	c.frame += asz;
	let off: i32 = 0 - c.frame;
	let l: *local = amalloc(c.a, 48u64): *local;
	l.name = name;
	l.off = off;
	l.tnode = tnode;
	l.lnext = c.locals;
	c.locals = l;
	return off;
};

fn local_add(c: *cgen, name: str, sz: i32, tnode: *node) i32 = {
	// Name-based slot reuse for N_LETs and params: if `name` is
	// already declared in this function, return its existing
	// offset. Mirrors C cgen (cmd/6c/cgen.c:localoff). Two
	// disjoint scopes that declare the same name share one slot —
	// so `escape` in wwdump (three `let cp: pos;` across separate
	// branches) reserves one slot, not three. scan_locals does
	// the matching dedup at prologue time so the SUBQ stays in
	// sync.
	//
	// On a dedup hit we also overwrite the stored tnode to match
	// the new declaration's type. C reads `n->lhs->type` (filled
	// by the checker) at every N_DOT/N_CAST site; we read
	// `lc.tnode`, so it must follow source order. Without this,
	// a later `let m: *node` inside a branch keeps an earlier
	// `let m: i32`'s tnode and `m.next` falls into the SB fallback.
	let cur: *local = c.locals;
	for (cur != nil) {
		let cn: str = cur.name;
		if (streq(cn, name)) {
			cur.tnode = tnode;
			return cur.off;
		};
		cur = cur.lnext;
	};
	return local_alloc(c, name, sz, tnode);
};

// scan_seen_mark — called by scan_locals on every let / match-bind
// site. Returns true if `name` is already tracked in c.locals (so
// the slot will be shared at emission time — no new frame bump).
// Otherwise appends a name-only stub and returns false. Stubs are
// thrown away when cgfn resets c.locals before emission.
fn scan_seen_mark(c: *cgen, name: str) bool = {
	if (local_find_node(c, name) != nil) { return true; };
	let l: *local = amalloc(c.a, 48u64): *local;
	l.name = name;
	l.off = 0;
	l.tnode = nil;
	l.lnext = c.locals;
	c.locals = l;
	return false;
};

fn local_find_node(c: *cgen, name: str) *local = {
	let l: *local = c.locals;
	for (l != nil) {
		let ln: str = l.name;
		if (streq(ln, name)) { return l; };
		l = l.lnext;
	};
	return nil;
};

fn local_find(c: *cgen, name: str) i32 = {
	let l: *local = c.locals;
	for (l != nil) {
		let ln: str = l.name;
		if (ln.len == name.len) {
			let i: i32 = 0;
			let eq: bool = true;
			for (i < name.len) {
				if (ln[i] != name[i]) { eq = false; i = name.len; }
				else { i += 1; };
			};
			if (eq) { return l.off; };
		};
		l = l.lnext;
	};
	return 0;
};

// ---- emit helpers ---------------------------------------------------

fn emit_line(s: str) void = { os.write(1, s.ptr, s.len: u64); };

fn emit_int(v: i64) void = {
	let buf: [32]u8;
	let n: i32 = strconv.i64toa(buf[0:32], v);
	os.write(1, buf.ptr, n: u64);
};

fn emit_uint(v: u64) void = {
	let buf: [32]u8;
	let n: i32 = strconv.u64toa(buf[0:32], v);
	os.write(1, buf.ptr, n: u64);
};

// emit_disp_reg — print "disp(reg)" or "(reg)" when disp == 0, the
// way Plan 9 6c/6a do.
fn emit_disp_reg(off: i64, reg: str) void = {
	if (off != 0i64) { emit_int(off); };
	emit_line("(");
	emit_line(reg);
	emit_line(")");
};

// emit_off — print an integer offset, suppressing it entirely when 0.
// Use before any emit_line("(BP)...") or emit_line("(SB)...") sequence.
// Plan 9 cc convention: "(BP)" not "0(BP)".
fn emit_off(v: i64) void = {
	if (v != 0i64) { emit_int(v); };
};

// mklabel — fresh label "<fnname>_<base>_<seq>". Returns an
// arena-owned str. Mirrors C cgen's mklabel so diffs match.
fn mklabel(c: *cgen, base: str) str = {
	let buf: [128]u8;
	let i: i32 = 0;
	let fname: str = c.fn_name;
	let j: i32 = 0;
	for (j < fname.len) {
		buf[i] = fname[j];
		i += 1; j += 1;
	};
	buf[i] = 95u8; i += 1;	// '_'
	j = 0;
	for (j < base.len) {
		buf[i] = base[j];
		i += 1; j += 1;
	};
	buf[i] = 95u8; i += 1;	// '_'
	let n: i32 = strconv.i64toa(buf[i:128], c.labelseq: i64);
	c.labelseq += 1;
	let total: i32 = i + n;
	let p: *u8 = amalloc(c.a, (total: u64) + 1u64): *u8;
	let k: i32 = 0;
	for (k < total) {
		p[k] = buf[k];
		k += 1;
	};
	p[total] = 0u8;
	let r: str;
	r.ptr = p;
	r.len = total;
	return r;
};

fn emit_label(s: str) void = {
	os.write(1, s.ptr, s.len: u64);
	emit_line(":\n");
};

// ---- string interning ------------------------------------------------
//
// streq is provided by sym.ww and reused here.

// intern_strlit — return a stable label for `bytes`. Dedups by content
// so identical literals share storage.
fn intern_strlit(c: *cgen, bytes: str) str = {
	let s: *strlit = c.strlits;
	for (s != nil) {
		let bs: str = s.bytes;
		if (streq(bs, bytes)) {
			return s.label;
		};
		s = s.slnext;
	};
	// New label "_S_<seq>".
	let buf: [32]u8;
	buf[0] = 95u8; buf[1] = 83u8; buf[2] = 95u8;	// "_S_"
	let n: i32 = strconv.i64toa(buf[3:32], c.strlit_seq: i64);
	c.strlit_seq += 1;
	let total: i32 = 3 + n;
	let p: *u8 = amalloc(c.a, (total: u64) + 1u64): *u8;
	let i: i32 = 0;
	for (i < total) { p[i] = buf[i]; i += 1; };
	p[total] = 0u8;
	let lab: str;
	lab.ptr = p;
	lab.len = total;
	let nw: *strlit = amalloc(c.a, 48u64): *strlit;
	nw.label = lab;
	nw.bytes = bytes;
	nw.slnext = c.strlits;
	c.strlits = nw;
	return lab;
};

// emit_def_constants — DATA directive per top-level int-literal `def`.
// 8 bytes little-endian to match what the C cgen emits.
fn emit_def_constants(c: *cgen, file: *node) void = {
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_DEF) {
			let r: *node = d.rhs;
			let v: u64 = 0u64;
			let ok: bool = false;
			if (r != nil) {
				if (r.kind == N_INTLIT)  { v = r.uval; ok = true; };
				if (r.kind == N_RUNELIT) { v = r.uval; ok = true; };
				if (r.kind == N_TRUE)    { v = 1u64;   ok = true; };
				if (r.kind == N_FALSE)   { v = 0u64;   ok = true; };
				if (r.kind == N_NIL)     { v = 0u64;   ok = true; };
			};
			if (ok) {
				emit_line("DATA ");
				let nm: str = d.str;
				os.write(1, nm.ptr, nm.len: u64);
				emit_line("(SB),\"");
				let i: i32 = 0;
				let n: u64 = v;
				for (i < 8) {
					let b: u8 = (n & 255u64): u8;
					n = n >> 8u64;
					// C emit_defs only special-cases " and \;
					// every other non-printable goes as \xHH.
					if (b == 34u8) { emit_line("\\\""); }
					else { if (b == 92u8) { emit_line("\\\\"); }
					else {
						if (b < 32u8) {
							emit_line("\\x");
							let hi: u8 = b >> 4u8;
							let lo: u8 = b & 15u8;
							let bb: [2]u8;
							if (hi < 10u8) { bb[0] = hi + 48u8; }
							else { bb[0] = (hi - 10u8) + 97u8; };
							if (lo < 10u8) { bb[1] = lo + 48u8; }
							else { bb[1] = (lo - 10u8) + 97u8; };
							os.write(1, bb.ptr, 2u64);
						} else {
							if (b >= 127u8) {
								emit_line("\\x");
								let hi: u8 = b >> 4u8;
								let lo: u8 = b & 15u8;
								let bb: [2]u8;
								if (hi < 10u8) { bb[0] = hi + 48u8; }
								else { bb[0] = (hi - 10u8) + 97u8; };
								if (lo < 10u8) { bb[1] = lo + 48u8; }
								else { bb[1] = (lo - 10u8) + 97u8; };
								os.write(1, bb.ptr, 2u64);
							} else {
								let bb: [1]u8;
								bb[0] = b;
								os.write(1, bb.ptr, 1u64);
							};
						};
					};};
					i += 1;
				};
				emit_line("\"\n");
			};
		};
		d = d.next;
	};
};

// emit_data_section — DATA directives for every interned strlit.
// Trailing NUL appended so .ptr can be used as a C string by syscalls.
fn emit_data_section(c: *cgen) void = {
	let s: *strlit = c.strlits;
	for (s != nil) {
		emit_line("DATA ");
		let lab: str = s.label;
		os.write(1, lab.ptr, lab.len: u64);
		emit_line("(SB),\"");
		let bs: str = s.bytes;
		let i: i32 = 0;
		for (i < bs.len) {
			let b: u8 = bs[i];
			if (b == 34u8) { emit_line("\\\""); }	// "
			else { if (b == 92u8) { emit_line("\\\\"); }	// \
			else { if (b == 10u8) { emit_line("\\n"); }
			else { if (b == 9u8)  { emit_line("\\t"); }
			else { if (b == 13u8) { emit_line("\\r"); }
			else {
				if (b < 32u8) {
					emit_line("\\x");
					let hi: u8 = b >> 4u8;
					let lo: u8 = b & 15u8;
					let bb: [2]u8;
					if (hi < 10u8) { bb[0] = hi + 48u8; }
					else { bb[0] = (hi - 10u8) + 97u8; };
					if (lo < 10u8) { bb[1] = lo + 48u8; }
					else { bb[1] = (lo - 10u8) + 97u8; };
					os.write(1, bb.ptr, 2u64);
				} else {
					if (b >= 127u8) {
						emit_line("\\x");
						let hi: u8 = b >> 4u8;
						let lo: u8 = b & 15u8;
						let bb: [2]u8;
						if (hi < 10u8) { bb[0] = hi + 48u8; }
						else { bb[0] = (hi - 10u8) + 97u8; };
						if (lo < 10u8) { bb[1] = lo + 48u8; }
						else { bb[1] = (lo - 10u8) + 97u8; };
						os.write(1, bb.ptr, 2u64);
					} else {
						let bb: [1]u8;
						bb[0] = b;
						os.write(1, bb.ptr, 1u64);
					};
				};
			};};};};};
			i += 1;
		};
		emit_line("\\x00\"\n");
		s = s.slnext;
	};
};

// ---- fn return-type map ---------------------------------------------
//
// Per-file: ident → ret-type-node. Used to decide whether to shuffle
// (AX, DX) → (AX, BX) after a CALL — needed for str-returning fns so
// the value flows through cgen as the canonical (AX, BX) str pair.

type fnret = struct {
	fname: str,
	rtype: *node,
	frnext: *fnret,
};

fn collect_fnrets(c: *cgen, file: *node) void = {
	c.fnrets = nil;
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_FNDECL) {
			let f: *fnret = amalloc(c.a, 32u64): *fnret;
			f.fname = d.str;
			f.rtype = d.lhs;
			f.frnext = c.fnrets;
			c.fnrets = f;
		};
		d = d.next;
	};
};

fn fnret_lookup(c: *cgen, name: str) *node = {
	let f: *fnret = c.fnrets;
	for (f != nil) {
		let fn_: str = f.fname;
		if (streq(fn_, name)) { return f.rtype; };
		f = f.frnext;
	};
	return nil;
};

// ---- def-constant registry ------------------------------------------
//
// `def NAME: T = LIT;` becomes a DATA symbol the C-side 6c emits; an
// ident reference loads it via `MOVQ NAME(SB), AX`. We collect them at
// file load and consult on N_IDENT lookup.

type def_ent = struct {
	dname: str,
	dnext: *def_ent,
};

fn collect_defs(c: *cgen, file: *node) void = {
	c.defs = nil;
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_DEF) {
			let e: *def_ent = amalloc(c.a, 32u64): *def_ent;
			e.dname = d.str;
			e.dnext = c.defs;
			c.defs = e;
		};
		d = d.next;
	};
};

fn def_lookup(c: *cgen, name: str) bool = {
	let e: *def_ent = c.defs;
	for (e != nil) {
		let dn: str = e.dname;
		if (streq(dn, name)) { return true; };
		e = e.dnext;
	};
	return false;
};

// ---- FFI map ---------------------------------------------------------

fn ffi_collect(c: *cgen, file: *node) void = {
	c.ffis = nil;
	if (file == nil) { return; };
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_FNDECL) {
			let a: *node = d.attr;
			for (a != nil) {
				if (a.kind == N_ATTR) {
					let aname: str = a.str;
					if (streq(aname, "symbol")) {
						let sym_node: *node = a.list;
						if (sym_node != nil) {
							if (sym_node.kind == N_STRLIT) {
								let f: *ffi = amalloc(c.a, 48u64): *ffi;
								f.ident  = d.str;
								f.symbol = sym_node.str;
								f.fnext  = c.ffis;
								c.ffis   = f;
							};
						};
					};
				};
				a = a.next;
			};
		};
		d = d.next;
	};
};

fn ffi_resolve(c: *cgen, ident: str) str = {
	let f: *ffi = c.ffis;
	for (f != nil) {
		let id: str = f.ident;
		if (streq(id, ident)) { return f.symbol; };
		f = f.fnext;
	};
	return ident;
};

// ---- ABI argreg helpers ---------------------------------------------

fn argreg_name(i: i32) str = {
	if (i == 0) { return "DI"; };
	if (i == 1) { return "SI"; };
	if (i == 2) { return "DX"; };
	if (i == 3) { return "CX"; };
	if (i == 4) { return "R8"; };
	if (i == 5) { return "R9"; };
	return "?";
};

// ---- expression cgen -------------------------------------------------

// push_args_rev — recursively walks the arg list, evaluates rightmost
// first, and pushes. str args take two slots (ptr in AX, len in BX);
// the order on the stack so a left-to-right pop into argregs lands
// (ptr, len) correctly is: PUSHQ BX (top), PUSHQ AX (above) — the
// pop sequence then yields AX, then BX.
fn push_args_rev(c: *cgen, arg: *node) i32 = {
	if (arg == nil) { return 0; };
	let rest: i32 = push_args_rev(c, arg.next);
	// N_SLICE expression as arg: `buf[lo:hi]` builds a slice header
	// on the stack matching C cgen's sequence — push base, push hi,
	// compute lo, pop into BX/CX, derive len/ptr, push (cap, len, ptr).
	if (arg.kind == N_SLICE) {
		let base: *node = arg.lhs;
		let lo: *node = arg.rhs;
		let hi: *node = arg.cond;
		let base_local: *local = nil;
		if (base != nil) {
			if (base.kind == N_IDENT) {
				let bn: str = base.str;
				base_local = local_find_node(c, bn);
			};
		};
		// base address → push
		if (base_local != nil) {
			let tn: *node = base_local.tnode;
			if (tn != nil) {
				if (tn.kind == N_TARRAY) {
					emit_line("\tLEAQ\t");
					emit_off(base_local.off: i64);
					emit_line("(BP), AX\n");
				} else {
					emit_line("\tMOVQ\t");
					emit_off(base_local.off: i64);
					emit_line("(BP), AX\n");
				};
			} else {
				emit_line("\tMOVQ\t");
				emit_off(base_local.off: i64);
				emit_line("(BP), AX\n");
			};
		} else {
			cgexpr(c, base);
		};
		emit_line("\tPUSHQ\tAX\n");
		// hi (default base length) → push
		if (hi != nil) {
			cgexpr(c, hi);
		} else { if (base_local != nil) {
			let tn: *node = base_local.tnode;
			if (tn != nil) {
				if (tn.kind == N_TARRAY) {
					let len_n: *node = tn.rhs;
					if (len_n != nil) {
						if (len_n.kind == N_INTLIT) {
							emit_line("\tMOVQ\t$");
							emit_uint(len_n.uval);
							emit_line(", AX\n");
						};
					};
				} else { if (tn.kind == N_TSLICE) {
					emit_line("\tMOVQ\t");
					emit_off((base_local.off + 8): i64);
					emit_line("(BP), AX\n");
				} else { if (tn.kind == N_TNAME) {
					if (streq(tn.str, "str")) {
						emit_line("\tMOVQ\t");
						emit_off((base_local.off + 8): i64);
						emit_line("(BP), AX\n");
					};
				};};};
			};
		} else {
			emit_line("\tMOVQ\t$0, AX\n");
		};};
		emit_line("\tPUSHQ\tAX\n");
		// lo (default 0) → AX
		if (lo != nil) { cgexpr(c, lo); }
		else { emit_line("\tMOVQ\t$0, AX\n"); };
		emit_line("\tPOPQ\tBX\n");           // hi
		emit_line("\tPOPQ\tCX\n");           // base
		emit_line("\tMOVQ\tBX, DX\n");       // DX = hi
		emit_line("\tSUBQ\tAX, DX\n");       // DX = hi - lo = len
		emit_line("\tADDQ\tAX, CX\n");       // CX = base + lo = ptr
		emit_line("\tPUSHQ\tDX\n");          // cap
		emit_line("\tPUSHQ\tDX\n");          // len
		emit_line("\tPUSHQ\tCX\n");          // ptr (top)
		return rest + 3;
	};
	// Slice/tagged ident args: emit per-register MOVQ+PUSHQ pairs in
	// reverse order (cap/v1, len/v0, ptr/tag) so a left-to-right pop
	// into argregs lands the canonical (ptr/tag, len/v0, cap/v1).
	if (arg.kind == N_IDENT) {
		let nm: str = arg.str;
		let lc: *local = local_find_node(c, nm);
		if (lc != nil) {
			let off: i32 = lc.off;
			if (is_slice_type(c, lc.tnode) || is_tagged_type(lc.tnode)) {
				emit_line("\tMOVQ\t");
				emit_off((off + 16): i64);
				emit_line("(BP), AX\n");
				emit_line("\tPUSHQ\tAX\n");
				emit_line("\tMOVQ\t");
				emit_off((off + 8): i64);
				emit_line("(BP), AX\n");
				emit_line("\tPUSHQ\tAX\n");
				emit_line("\tMOVQ\t");
				emit_off(off: i64);
				emit_line("(BP), AX\n");
				emit_line("\tPUSHQ\tAX\n");
				return rest + 3;
			};
		};
	};
	cgexpr(c, arg);
	if (node_isslice(c, arg)) {
		emit_line("\tPUSHQ\tCX\n");
		emit_line("\tPUSHQ\tBX\n");
		emit_line("\tPUSHQ\tAX\n");
		return rest + 3;
	};
	if (node_isstr(c, arg)) {
		emit_line("\tPUSHQ\tBX\n");
		emit_line("\tPUSHQ\tAX\n");
		return rest + 2;
	};
	emit_line("\tPUSHQ\tAX\n");
	return rest + 1;
};

fn node_isslice(c: *cgen, n: *node) bool = {
	if (n == nil) { return false; };
	let k: i32 = n.kind;
	if (k == N_IDENT) {
		let nm: str = n.str;
		let lc: *local = local_find_node(c, nm);
		if (lc != nil) { return is_slice_type(c, lc.tnode); };
		return false;
	};
	if (k == N_SLICE) { return true; };
	return false;
};

// node_isstr — best-effort surface check: does this expression
// evaluate to a str value? Used to drive the call-arg push convention
// (str args take two slots: ptr + len).
fn node_isstr(c: *cgen, n: *node) bool = {
	if (n == nil) { return false; };
	let k: i32 = n.kind;
	if (k == N_STRLIT) { return true; };
	if (k == N_IDENT) {
		let nm: str = n.str;
		let lc: *local = local_find_node(c, nm);
		if (lc != nil) {
			let tn: *node = lc.tnode;
			if (tn != nil) {
				if (tn.kind == N_TNAME) {
					let tnm: str = tn.str;
					if (streq(tnm, "str")) { return true; };
				};
			};
		};
		return false;
	};
	if (k == N_CALL) {
		let callee: *node = n.lhs;
		if (callee != nil) {
			if (callee.kind == N_IDENT) {
				let cnm: str = callee.str;
				let rt: *node = fnret_lookup(c, cnm);
				return is_str_type(c, rt);
			};
		};
		return false;
	};
	if (k == N_DOT) {
		let base: *node = n.lhs;
		let fld: str = n.str;
		// `<expr>.ptr` is *u8 not str; `<expr>.len` is i32 not str.
		if (streq(fld, "ptr")) { return false; };
		if (streq(fld, "len")) { return false; };
		if (streq(fld, "cap")) { return false; };
		if (base != nil) {
			let sname: str;
			sname.ptr = nil; sname.len = 0;
			if (base.kind == N_IDENT) {
				let lc: *local = local_find_node(c, base.str);
				if (lc != nil) {
					let tn: *node = lc.tnode;
					let lkind: i32 = -1;
					if (tn != nil) { lkind = tn.kind; };
					if (lkind == N_TNAME) { sname = tn.str; };
					if (lkind == N_TPTR) {
						let inner: *node = tn.lhs;
						if (inner != nil) {
							if (inner.kind == N_TNAME) { sname = inner.str; };
						};
					};
				};
			};
			// Chained dot (`p.foo.bar`): use dot_inner_struct_ptr
			// to resolve the inner chain to the *struct it lands
			// on, then look up `fld` in that struct.
			if (base.kind == N_DOT) {
				let inner_t: *node = dot_inner_struct_ptr(c, base);
				if (inner_t != nil) {
					if (inner_t.kind == N_TNAME) { sname = inner_t.str; };
				};
			};
			if (sname.len > 0) {
				let si: *struct_info = struct_lookup(c, sname);
				if (si != nil) {
					let fi: *field_info = si.fields;
					for (fi != nil) {
						let fn_: str = fi.fname;
						if (streq(fn_, fld)) {
							return is_str_type(c, fi.tnode);
						};
						fi = fi.finext;
					};
				};
			};
		};
		return false;
	};
	if (k == N_CAST) {
		return is_str_type(c, n.rhs);
	};
	return false;
};

// type_name_isunsigned — true for u8/u16/u32/u64/uint/uintptr.
fn type_name_isunsigned(nm: str) bool = {
	if (streq(nm, "u8"))   { return true; };
	if (streq(nm, "u16"))  { return true; };
	if (streq(nm, "u32"))  { return true; };
	if (streq(nm, "u64"))  { return true; };
	if (streq(nm, "uint")) { return true; };
	if (streq(nm, "uintptr")) { return true; };
	return false;
};

// type_node_isunsigned — recurse through TNAME / TPTR / TSLICE etc.
fn type_node_isunsigned(t: *node) bool = {
	if (t == nil) { return false; };
	if (t.kind == N_TNAME) { return type_name_isunsigned(t.str); };
	return false;
};

// type_is_8byte_primitive — does this type take exactly one 8-byte
// slot (pointer / fn-ptr / 64-bit int / chan / scalar primitive
// padded up to 8) rather than a wider aggregate? Used by N_LET
// zero-init to mirror C cgen's "only zero if sz == 8 at the type
// level" rule. Strings (16), slices (24), tagged unions (>=16),
// tuples (16), structs (varies), arrays — all fall through to
// false here even when their *slot* rounds up to 8.
fn type_is_8byte_primitive(c: *cgen, t: *node) bool = {
	if (t == nil) { return false; };
	let k: i32 = t.kind;
	if (k == N_TPTR)   { return true; };
	if (k == N_TFN)    { return true; };
	if (k == N_TCHAN)  { return true; };
	if (k == N_TSLICE) { return false; };
	if (k == N_TARRAY) { return false; };
	if (k == N_TTUPLE) { return false; };
	if (k == N_TTAGGED){ return false; };
	if (k == N_TNAME) {
		let nm: str = t.str;
		if (streq(nm, "str")) { return false; };
		// Struct alias: not a primitive even if the slot is 8B.
		if (struct_lookup(c, nm) != nil) { return false; };
		// Primitive (i8/u8/.../i64/u64/bool/rune/f32/f64/int/...).
		// All of these get slot-padded to 8 and zero-init in C.
		if (prim_size(nm) > 0) { return true; };
		return false;
	};
	return false;
};

// type_name_issigned — true for i8/i16/i32/i64/int/rune.
fn type_name_issigned(nm: str) bool = {
	if (streq(nm, "i8"))   { return true; };
	if (streq(nm, "i16"))  { return true; };
	if (streq(nm, "i32"))  { return true; };
	if (streq(nm, "i64"))  { return true; };
	if (streq(nm, "int"))  { return true; };
	if (streq(nm, "rune")) { return true; };
	return false;
};

// field_load_op — pick the load instruction for a non-str struct
// field by its declared size + signedness. Mirrors the C cgen op
// dispatch (MOVZBQ for u8/bool/i8, MOVSXD for i32, MOVL for u32, MOVQ
// for 8-byte). f might be nil for fields outside our struct registry.
fn field_load_op(f: *field_info) str = {
	if (f == nil) { return "MOVQ"; };
	let sz: i32 = f.fsz;
	if (sz == 1) { return "MOVZBQ"; };
	if (sz == 4) {
		let t: *node = f.tnode;
		if (t != nil) {
			if (t.kind == N_TNAME) {
				if (type_name_issigned(t.str)) { return "MOVSXD"; };
			};
		};
		return "MOVL";
	};
	return "MOVQ";
};

// field_store_op — pick the store instruction for a non-str struct
// field by its declared size. MOVB for 1, MOVL for 4, MOVQ for 8.
fn field_store_op(f: *field_info) str = {
	if (f == nil) { return "MOVQ"; };
	let sz: i32 = f.fsz;
	if (sz == 1) { return "MOVB"; };
	if (sz == 4) { return "MOVL"; };
	return "MOVQ";
};

// index_base_esz — element size for `arr[i]` where the base is a
// chained-dot pseudo-field `s.ptr` (s being str/*str/slice/*slice).
// For str the element is one byte; for `[]T` / `*[]T` we drill into
// the slice element type.
fn index_base_esz(c: *cgen, base: *node) i32 = {
	if (base == nil) { return 8; };
	if (base.kind != N_DOT) { return 8; };
	let fld: str = base.str;
	let inner: *node = base.lhs;
	if (inner == nil) { return 8; };
	if (inner.kind != N_IDENT) { return 8; };
	let nm: str = inner.str;
	let lc: *local = local_find_node(c, nm);
	if (lc == nil) { return 8; };
	let tn: *node = lc.tnode;
	if (tn == nil) { return 8; };

	// `.ptr` pseudo-field on str/slice → element of the str/slice.
	if (streq(fld, "ptr")) {
		let inner_t: *node = tn;
		if (tn.kind == N_TPTR) { inner_t = tn.lhs; };
		if (inner_t == nil) { return 8; };
		if (inner_t.kind == N_TNAME) {
			if (streq(inner_t.str, "str")) { return 1; };
		};
		if (inner_t.kind == N_TSLICE) { return elem_size_of(inner_t); };
		return 8;
	};

	// Generic struct field: if it's *T, element size is T's size.
	let lkind: i32 = tn.kind;
	let sname: str;
	sname.ptr = nil; sname.len = 0;
	if (lkind == N_TNAME) { sname = tn.str; };
	if (lkind == N_TPTR) {
		let pinner: *node = tn.lhs;
		if (pinner != nil) {
			if (pinner.kind == N_TNAME) { sname = pinner.str; };
		};
	};
	if (sname.len == 0) { return 8; };
	let si: *struct_info = struct_lookup(c, sname);
	if (si == nil) { return 8; };
	let fi: *field_info = si.fields;
	for (fi != nil) {
		let fn_: str = fi.fname;
		if (streq(fn_, fld)) {
			let ft: *node = fi.tnode;
			if (ft == nil) { return 8; };
			if (ft.kind == N_TPTR) {
				let elem: *node = ft.lhs;
				if (elem != nil) {
					if (elem.kind == N_TNAME) {
						if (streq(elem.str, "str")) { return 16; };
						let ps: i32 = prim_size(elem.str);
						if (ps > 0) { return ps; };
					};
				};
				return 8;
			};
			if (ft.kind == N_TSLICE) { return elem_size_of(ft); };
			// str-typed field: indexing yields one byte
			// (`n.s[i]` where .s is str — matches C cgen's
			// MOVZBQ for byte indexing).
			if (ft.kind == N_TNAME) {
				if (streq(ft.str, "str")) { return 1; };
			};
			return 8;
		};
		fi = fi.finext;
	};
	return 8;
};

// dot_inner_struct_ptr — for an N_DOT whose lhs is a chain of dots
// or an N_IDENT, walk the chain and return the N_TNAME tnode of the
// struct that the chain dereferences to (i.e., for `r.sym` where
// .sym is *lsym, return N_TNAME("lsym")). Returns nil if the chain
// doesn't resolve to a *struct.
//
// Used by the chained-DOT cgen path so `r.sym.val` knows the outer
// is a field of `lsym`.
fn dot_inner_struct_ptr(c: *cgen, n: *node) *node = {
	if (n == nil) { return nil; };
	if (n.kind != N_DOT) { return nil; };
	let base: *node = n.lhs;
	let fld: str = n.str;
	if (base == nil) { return nil; };

	// Resolve base's struct tnode.
	let base_t: *node = nil;
	if (base.kind == N_IDENT) {
		let lc: *local = local_find_node(c, base.str);
		if (lc == nil) { return nil; };
		let tn: *node = lc.tnode;
		if (tn == nil) { return nil; };
		// base could be either struct-by-value (N_TNAME) or *struct (N_TPTR).
		if (tn.kind == N_TNAME) { base_t = tn; };
		if (tn.kind == N_TPTR)  { base_t = tn.lhs; };
	} else { if (base.kind == N_DOT) {
		base_t = dot_inner_struct_ptr(c, base);
	};};
	if (base_t == nil) { return nil; };
	if (base_t.kind != N_TNAME) { return nil; };

	// Look up the struct, find the field, return the field's *struct.
	let si: *struct_info = struct_lookup(c, base_t.str);
	if (si == nil) { return nil; };
	let fi: *field_info = si.fields;
	for (fi != nil) {
		if (streq(fi.fname, fld)) {
			let ft: *node = fi.tnode;
			if (ft == nil) { return nil; };
			if (ft.kind != N_TPTR) { return nil; };
			let inner: *node = ft.lhs;
			if (inner == nil) { return nil; };
			if (inner.kind != N_TNAME) { return nil; };
			return inner;
		};
		fi = fi.finext;
	};
	return nil;
};

// elem_size_of — given the type node of an indexable (`*T`, `[]T`,
// `[N]T`, `str`), return the byte size of one element (1 for u8/i8/
// bool/str-byte, 8 otherwise — same shape as C cgen's esz fallback).
fn elem_size_of(t: *node) i32 = {
	if (t == nil) { return 1; };
	let k: i32 = t.kind;
	let elem: *node = nil;
	if (k == N_TPTR)   { elem = t.lhs; };
	if (k == N_TSLICE) { elem = t.lhs; };
	if (k == N_TARRAY) { elem = t.lhs; };
	if (k == N_TNAME) {
		let nm: str = t.str;
		if (streq(nm, "str")) { return 1; };
		// Indexing a primitive name (rare): element size = the prim.
		let ps: i32 = prim_size(nm);
		if (ps > 0) { return ps; };
		return 1;
	};
	if (elem == nil) { return 1; };
	if (elem.kind == N_TNAME) {
		let nm: str = elem.str;
		// str element is 16B (ptr+len). prim_size returns 0 for it.
		if (streq(nm, "str")) { return 16; };
		let ps: i32 = prim_size(nm);
		if (ps > 0) { return ps; };
	};
	return 8;
};

// node_isunsigned — best-effort cgen-time inference from the AST. We
// don't have a typed AST yet, so we walk surface nodes:
//   N_INTLIT      — never marked unsigned (no tsuffix plumbing yet)
//   N_IDENT       — look up the local's declared type
//   N_DOT         — look up the field's declared type via struct reg
//   N_BIN / N_UN  — recurse: unsigned if either operand is unsigned
//   N_CAST        — use the cast target type
//
// Conservative: if we can't tell, return false (signed). The cost of
// being wrong here is byte-different asm vs C, not bad runtime.
fn node_isunsigned(c: *cgen, n: *node) bool = {
	if (n == nil) { return false; };
	let k: i32 = n.kind;
	if (k == N_IDENT) {
		let nm: str = n.str;
		let lc: *local = local_find_node(c, nm);
		if (lc != nil) { return type_node_isunsigned(lc.tnode); };
		return false;
	};
	if (k == N_DOT) {
		let base: *node = n.lhs;
		let fld: str = n.str;
		if (base != nil) {
			if (base.kind == N_IDENT) {
				let bn: str = base.str;
				let lc: *local = local_find_node(c, bn);
				if (lc != nil) {
					let tn: *node = lc.tnode;
					let lkind: i32 = -1;
					if (tn != nil) { lkind = tn.kind; };
					let sname: str;
					sname.ptr = nil; sname.len = 0;
					if (lkind == N_TPTR) {
						let inner: *node = tn.lhs;
						if (inner != nil) {
							if (inner.kind == N_TNAME) { sname = inner.str; };
						};
					};
					if (lkind == N_TNAME) { sname = tn.str; };
					if (sname.len > 0) {
						let si: *struct_info = struct_lookup(c, sname);
						if (si != nil) {
							let fi: *field_info = si.fields;
							for (fi != nil) {
								let fn_: str = fi.fname;
								if (streq(fn_, fld)) {
									return type_node_isunsigned(fi.tnode);
								};
								fi = fi.finext;
							};
						};
					};
				};
			};
		};
		return false;
	};
	if (k == N_CAST) { return type_node_isunsigned(n.rhs); };
	if (k == N_BIN) {
		if (node_isunsigned(c, n.lhs)) { return true; };
		return node_isunsigned(c, n.rhs);
	};
	if (k == N_UN) { return node_isunsigned(c, n.lhs); };
	// N_INDEX: `p[i]` is unsigned iff p's element type is unsigned.
	// Walks the base local's declared type and pulls the element
	// out — *u8 → u8, [N]u32 → u32, []u64 → u64. Without this the
	// compare-codegen for `p[i] >= 48u8` falls back to signed JGE
	// instead of JAE, diverging from C 6c on byte indexing.
	if (k == N_INDEX) {
		let base: *node = n.lhs;
		if (base != nil) {
			if (base.kind == N_IDENT) {
				let lc: *local = local_find_node(c, base.str);
				if (lc != nil) {
					let tn: *node = lc.tnode;
					if (tn != nil) {
						let elem: *node = nil;
						if (tn.kind == N_TPTR)   { elem = tn.lhs; };
						if (tn.kind == N_TARRAY) { elem = tn.lhs; };
						if (tn.kind == N_TSLICE) { elem = tn.lhs; };
						if (elem != nil) {
							return type_node_isunsigned(elem);
						};
					};
				};
			};
		};
		return false;
	};
	return false;
};

fn cgexpr(c: *cgen, n: *node) void = {
	if (n == nil) { return; };
	let k: i32 = n.kind;

	if (k == N_INTLIT) {
		// Print signed (i64), not unsigned (u64). C cgen uses
		// `$%lld` so 64-bit constants with bit 63 set show up as
		// negative — e.g. FNV-1a's offset basis prints as
		// $-3750763034362895579, not $14695981039346656037.
		emit_line("\tMOVQ\t$");
		emit_int(n.uval: i64);
		emit_line(", AX\n");
		return;
	};
	if (k == N_RUNELIT) {
		emit_line("\tMOVQ\t$");
		emit_int(n.uval: i64);
		emit_line(", AX\n");
		return;
	};
	if (k == N_STRLIT) {
		// Result is the (ptr, len) pair: ptr in AX, len in BX. Call
		// sites that expect a str arg pick these up directly.
		let nstr: str = n.str;
		let lab: str = intern_strlit(c, nstr);
		emit_line("\tLEAQ\t");
		os.write(1, lab.ptr, lab.len: u64);
		emit_line("(SB), AX\n");
		emit_line("\tMOVQ\t$");
		emit_int(nstr.len: i64);
		emit_line(", BX\n");
		return;
	};
	if (k == N_TRUE) {
		emit_line("\tMOVQ\t$1, AX\n");
		return;
	};
	if (k == N_FALSE) {
		emit_line("\tMOVQ\t$0, AX\n");
		return;
	};
	if (k == N_NIL) {
		emit_line("\tMOVQ\t$0, AX\n");
		return;
	};

	if (k == N_IDENT) {
		let nm: str = n.str;
		let lc: *local = local_find_node(c, nm);
		if (lc != nil) {
			let off: i32 = lc.off;
			emit_line("\tMOVQ\t");
			emit_off(off: i64);
			emit_line("(BP), AX\n");
			// str local: also load the len half into BX.
			if (is_str_type(c, lc.tnode)) {
				emit_line("\tMOVQ\t");
				emit_off((off + 8): i64);
				emit_line("(BP), BX\n");
			};
			// slice local: load (ptr, len, cap) into (AX, BX, CX).
			if (is_slice_type(c, lc.tnode)) {
				emit_line("\tMOVQ\t");
				emit_off((off + 8): i64);
				emit_line("(BP), BX\n");
				emit_line("\tMOVQ\t");
				emit_off((off + 16): i64);
				emit_line("(BP), CX\n");
			};
			return;
		};
		// Top-level `def` constant — load from its DATA symbol.
		if (def_lookup(c, nm)) {
			emit_line("\tMOVQ\t");
			os.write(1, nm.ptr, nm.len: u64);
			emit_line("(SB), AX\n");
			return;
		};
		// Fn-name used as a value (e.g. `let f = some_fn;` or
		// `... = some_fn;`). LEAQ the symbol address into AX —
		// resolved through ffi_resolve so a body-less FFI binding
		// emits the C symbol it was declared with via @symbol(),
		// not the ww-side ident.
		let rt: *node = fnret_lookup(c, nm);
		if (rt != nil) {
			let resolved: str = ffi_resolve(c, nm);
			emit_line("\tLEAQ\t");
			os.write(1, resolved.ptr, resolved.len: u64);
			emit_line("(SB), AX\n");
			return;
		};
		return;
	};

	if (k == N_INDEX) {
		// Element-size-aware load: u8-element bases use MOVZBQ,
		// everything else MOVQ. Fast path when the base is a bare
		// ident (mem.ww shape).
		let base: *node = n.lhs;
		let idx: *node = n.rhs;
		let esz: i32 = 8;
		let base_local: *local = nil;
		if (base != nil) {
			if (base.kind == N_IDENT) {
				let bn: str = base.str;
				base_local = local_find_node(c, bn);
				if (base_local != nil) { esz = elem_size_of(base_local.tnode); };
			} else { if (base.kind == N_DOT) {
				esz = index_base_esz(c, base);
			};};
		};
		cgexpr(c, idx);
		if (esz > 1) {
			emit_line("\tMOVQ\t$");
			emit_int(esz: i64);
			emit_line(", CX\n");
			emit_line("\tIMULQ\tCX, AX\n");
		};
		if (base_local != nil) {
			let tn: *node = base_local.tnode;
			let is_array: bool = false;
			if (tn != nil) { if (tn.kind == N_TARRAY) { is_array = true; }; };
			if (is_array) {
				emit_line("\tLEAQ\t");
				emit_off(base_local.off: i64);
				emit_line("(BP), BX\n");
			} else {
				emit_line("\tMOVQ\t");
				emit_off(base_local.off: i64);
				emit_line("(BP), BX\n");
			};
			emit_line("\tADDQ\tAX, BX\n");
			// str element (16B): load (ptr, len) into (AX, BX) so
			// the value flows through the str-rhs convention.
			if (esz == 16) {
				emit_line("\tMOVQ\t8(BX), CX\n");
				emit_line("\tMOVQ\t(BX), AX\n");
				emit_line("\tMOVQ\tCX, BX\n");
				return;
			};
			if (esz == 1) { emit_line("\tMOVZBQ\t(BX), AX\n"); }
			else          { emit_line("\tMOVQ\t(BX), AX\n"); };
			return;
		};
		// Generic fallback when base isn't a plain ident.
		emit_line("\tPUSHQ\tAX\n");
		cgexpr(c, base);
		emit_line("\tPOPQ\tBX\n");
		emit_line("\tADDQ\tBX, AX\n");
		if (esz == 16) {
			emit_line("\tMOVQ\t8(AX), BX\n");
			emit_line("\tMOVQ\t(AX), AX\n");
			return;
		};
		if (esz == 1) { emit_line("\tMOVZBQ\t(AX), AX\n"); }
		else          { emit_line("\tMOVQ\t(AX), AX\n"); };
		return;
	};

	if (k == N_MATCH) {
		// match (e) { case let v: T => stmt; ... }
		//
		// Read the tagged-union slot and dispatch by tag. Slot
		// layout: [+0]=tag, [+8]=value0, [+16]=value1. Bindings
		// (`case let v: T =>`) get a fresh local slot loaded from
		// slot+8 (and slot+16 for str-typed payload).
		let scrut: *node = n.lhs;
		let scrut_off: i32 = 0;
		let scrut_t: *node = nil;
		if (scrut != nil) {
			if (scrut.kind == N_IDENT) {
				let lc: *local = local_find_node(c, scrut.str);
				if (lc != nil) {
					scrut_off = lc.off;
					scrut_t = resolve_type(c, lc.tnode);
				};
			};
		};
		let endl: str = mklabel(c, "match_end");
		let cs: *node = n.list;
		for (cs != nil) {
			let nxt: str = mklabel(c, "match_next");
			let pat: *node = cs.lhs;
			// Compute the variant tag for this arm. Default arm
			// (no pattern) skips the tag check.
			if (pat != nil) {
				let want: i32 = 0;
				if (scrut_t != nil) {
					if (scrut_t.kind == N_TTAGGED) {
						let pat_name: str;
						pat_name.ptr = nil; pat_name.len = 0;
						if (pat.kind == N_TNAME) { pat_name = pat.str; };
						let v: *node = scrut_t.list;
						let idx: i32 = 0;
						let found: bool = false;
						for (v != nil) {
							if (v.kind == N_TNAME) {
								if (streq(v.str, pat_name)) {
									want = idx;
									found = true;
									v = nil;
								};
							};
							if (v != nil) {
								v = v.next;
								idx += 1;
							};
						};
						if (!found) { want = 0; };
					};
				};
				emit_line("\tMOVQ\t");
				emit_off(scrut_off: i64);
				emit_line("(BP), AX\n");
				emit_line("\tCMPQ\t$");
				emit_int(want: i64);
				emit_line(", AX\n");
				emit_line("\tJNE\t");
				emit_line(nxt);
				emit_line("\n");
			};
			// Bind `let v: T` from the slot, if requested.
			let bn: str = cs.str;
			if (bn.len > 0) {
				if (pat != nil) {
					let bsz: i32 = 8;
					if (is_str_type(c, pat)) { bsz = 16; };
					// local_alloc (not local_add): match-arm
					// binds don't dedup with same-named binds
					// in *other* matches, since C's cgexpr
					// allocates a fresh slot per match expr.
					let voff: i32 = local_alloc(c, bn, bsz, pat);
					emit_line("\tMOVQ\t");
					emit_off((scrut_off + 8): i64);
					emit_line("(BP), AX\n");
					emit_line("\tMOVQ\tAX, ");
					emit_off(voff: i64);
					emit_line("(BP)\n");
					if (bsz == 16) {
						emit_line("\tMOVQ\t");
						emit_off((scrut_off + 16): i64);
						emit_line("(BP), AX\n");
						emit_line("\tMOVQ\tAX, ");
						emit_off((voff + 8): i64);
						emit_line("(BP)\n");
					};
				};
			};
			// Body. Match arms are statements; we cgstmt them.
			if (cs.body != nil) { cgstmt(c, cs.body); };
			emit_line("\tJMP\t");
			emit_line(endl);
			emit_line("\n");
			emit_label(nxt);
			cs = cs.next;
		};
		emit_label(endl);
		return;
	};

	if (k == N_CAST) {
		// Type casts are mostly no-ops at the asm level for our
		// integer-shaped operands. Evaluate the source; AX holds
		// the bits unchanged. (Sign- or zero-extending narrow loads
		// to wider types is the loader's job, not cast's, in this
		// minimal cgen.)
		cgexpr(c, n.lhs);
		return;
	};

	if (k == N_DOT) {
		let lhs: *node = n.lhs;
		let fld: str = n.str;
		if (lhs != nil) {
			if (lhs.kind == N_IDENT) {
				let nm: str = lhs.str;
				let lc: *local = local_find_node(c, nm);
				if (lc != nil) {
					let tn: *node = lc.tnode;
					let lkind: i32 = -1;
					if (tn != nil) { lkind = tn.kind; };
					// Pointer-to-struct: deref then field load.
					if (lkind == N_TPTR) {
						let inner: *node = tn.lhs;
						let sname: str;
						sname.ptr = nil; sname.len = 0;
						if (inner != nil) {
							if (inner.kind == N_TNAME) {
								sname = inner.str;
							};
						};
						if (sname.len > 0) {
							let si: *struct_info = struct_lookup(c, sname);
							if (si != nil) {
								let fi: *field_info = si.fields;
								for (fi != nil) {
									let fn_: str = fi.fname;
									if (streq(fn_, fld)) {
										// str field via *struct: load len into a
										// scratch first (so loading ptr into AX
										// last leaves (AX=ptr, BX=len)).
										emit_line("\tMOVQ\t");
										emit_off(lc.off: i64);
										emit_line("(BP), BX\n");
										if (is_str_type(c, fi.tnode)) {
											emit_line("\tMOVQ\t");
											emit_disp_reg((fi.foff + 8): i64, "BX");
											emit_line(", CX\n");
											emit_line("\tMOVQ\t");
											emit_disp_reg(fi.foff: i64, "BX");
											emit_line(", AX\n");
											emit_line("\tMOVQ\tCX, BX\n");
										} else {
											let op: str = field_load_op(fi);
											emit_line("\t");
											emit_line(op);
											emit_line("\t");
											emit_disp_reg(fi.foff: i64, "BX");
											emit_line(", AX\n");
										};
										return;
									};
									fi = fi.finext;
								};
							};
						};
					};
					// Direct struct local: field load at off+foff.
					if (lkind == N_TNAME) {
						let sname: str = tn.str;
						let si: *struct_info = struct_lookup(c, sname);
						if (si != nil) {
							let fi: *field_info = si.fields;
							for (fi != nil) {
								let fn_: str = fi.fname;
								if (streq(fn_, fld)) {
									// str field: load both halves so chained
									// `.ptr` / `.len` see (AX=ptr, BX=len).
									if (is_str_type(c, fi.tnode)) {
										emit_line("\tMOVQ\t");
										emit_off((lc.off + fi.foff): i64);
										emit_line("(BP), AX\n");
										emit_line("\tMOVQ\t");
										emit_off((lc.off + fi.foff + 8): i64);
										emit_line("(BP), BX\n");
									} else {
										let op: str = field_load_op(fi);
										emit_line("\t");
										emit_line(op);
										emit_line("\t");
										emit_off((lc.off + fi.foff): i64);
										emit_line("(BP), AX\n");
									};
									return;
								};
								fi = fi.finext;
							};
						};
					};
					// Array pseudo-fields: `.ptr` is the array's
					// address (LEAQ); `.len` is the static element
					// count (immediate).
					if (lkind == N_TARRAY) {
						if (streq(fld, "ptr")) {
							emit_line("\tLEAQ\t");
							emit_off(lc.off: i64);
							emit_line("(BP), AX\n");
							return;
						};
						if (streq(fld, "len")) {
							let len_n: *node = tn.rhs;
							let alen: i64 = 0i64;
							if (len_n != nil) {
								if (len_n.kind == N_INTLIT) { alen = len_n.uval: i64; };
							};
							emit_line("\tMOVQ\t$");
							emit_int(alen);
							emit_line(", AX\n");
							return;
						};
					};
					// str/slice pseudo-fields .ptr/.len/.cap on a
					// direct local: load at slot+delta.
					let delta: i32 = -1;
					if (streq(fld, "ptr")) { delta = 0; };
					if (streq(fld, "len")) { delta = 8; };
					if (streq(fld, "cap")) { delta = 16; };
					if (delta >= 0) {
						// Pointer to str/slice (`*[]u8`, `*str`):
						// deref, then load at delta within the
						// pointed-to header. C cgen does the same.
						if (lkind == N_TPTR) {
							let inner: *node = tn.lhs;
							let inner_kind: i32 = -1;
							if (inner != nil) { inner_kind = inner.kind; };
							let inner_str: bool = false;
							if (inner_kind == N_TNAME) {
								if (streq(inner.str, "str")) { inner_str = true; };
							};
							if (inner_kind == N_TSLICE) { inner_str = true; };
							if (inner_str) {
								emit_line("\tMOVQ\t");
								emit_off(lc.off: i64);
								emit_line("(BP), BX\n");
								emit_line("\tMOVQ\t");
								emit_disp_reg(delta: i64, "BX");
								emit_line(", AX\n");
								return;
							};
						};
						emit_line("\tMOVQ\t");
						emit_off((lc.off + delta): i64);
						emit_line("(BP), AX\n");
						return;
					};
				};
			};
		};
		// Module-qualified value reference: `mod.name` where `mod`
		// is N_IDENT bound as SK_USE and the leaf isn't a local.
		// Treat as a SB symbol — `MOVQ leaf(SB), AX`. Same fallback
		// the C cgen takes when bt is NULL/ty_err.
		if (lhs != nil) {
			if (lhs.kind == N_IDENT) {
				emit_line("\tMOVQ\t");
				emit_line(fld);
				emit_line("(SB), AX\n");
				return;
			};
		};
		// Non-ident base pseudo-field: e.g. `"abc".ptr` / `"abc".len`.
		// Evaluate the str-producing expression — that leaves
		// (AX=ptr, BX=len). Then `.ptr` returns AX as is; `.len`
		// shuffles BX→AX. Mirrors what C cgen does (it just evaluates
		// the literal and picks the half it wants).
		if (streq(fld, "ptr")) { cgexpr(c, lhs); return; };
		if (streq(fld, "len")) {
			cgexpr(c, lhs);
			emit_line("\tMOVQ\tBX, AX\n");
			return;
		};
		// Chained struct-field-via-ptr-via-ptr access:
		//   r.sym.val   where r: *lrel, .sym: *lsym, .val: u64
		// Inner DOT (`r.sym`) returns a *struct (a pointer-to-struct
		// field). Outer DOT dereferences and reads `val`. Without this
		// path the cgen falls through and AX retains whatever the
		// inner expression left there — typically the *struct pointer
		// itself, so reads silently get the pointer value instead of
		// the field. (Showed up porting 6l/pass.ww.)
		if (lhs != nil) {
			if (lhs.kind == N_DOT) {
				let inner_t: *node = dot_inner_struct_ptr(c, lhs);
				if (inner_t != nil) {
					let sname: str = inner_t.str;
					let si: *struct_info = struct_lookup(c, sname);
					if (si != nil) {
						let fi: *field_info = si.fields;
						for (fi != nil) {
							if (streq(fi.fname, fld)) {
								cgexpr(c, lhs);	// AX = ptr to inner struct
								let lop: str = field_load_op(fi);
								// str field: load both halves.
								if (is_str_type(c, fi.tnode)) {
									emit_line("\tMOVQ\t");
									emit_disp_reg((fi.foff + 8): i64, "AX");
									emit_line(", BX\n");
									emit_line("\tMOVQ\t");
									emit_disp_reg(fi.foff: i64, "AX");
									emit_line(", AX\n");
									return;
								};
								emit_line("\t");
								emit_line(lop);
								emit_line("\t");
								emit_disp_reg(fi.foff: i64, "AX");
								emit_line(", AX\n");
								return;
							};
							fi = fi.finext;
						};
					};
				};
			};
		};
		return;
	};

	if (k == N_UN) {
		// Match C cgen ordering: evaluate operand first (load into AX),
		// then apply the unary op. AMP / STAR override AX with the
		// address / deref. The wasted load before AMP keeps our asm
		// byte-identical to the C version.
		cgexpr(c, n.lhs);
		if (n.op == TK_MINUS) { emit_line("\tNEGQ\tAX\n"); return; };
		if (n.op == TK_TILDE) { emit_line("\tNOTQ\tAX\n"); return; };
		if (n.op == TK_STAR)  { emit_line("\tMOVQ\t(AX), AX\n"); return; };
		if (n.op == TK_AMP) {
			let opnd: *node = n.lhs;
			if (opnd != nil) {
				if (opnd.kind == N_IDENT) {
					let nm: str = opnd.str;
					let off: i32 = local_find(c, nm);
					if (off != 0) {
						emit_line("\tLEAQ\t");
						emit_off(off: i64);
						emit_line("(BP), AX\n");
						return;
					};
				};
			};
			return;
		};
		if (n.op == TK_NOT) {
			let t: str = mklabel(c, "tt");
			let e: str = mklabel(c, "te");
			emit_line("\tCMPQ\t$0, AX\n");
			emit_line("\tJE\t");   emit_line(t); emit_line("\n");
			emit_line("\tMOVQ\t$0, AX\n");
			emit_line("\tJMP\t");  emit_line(e); emit_line("\n");
			emit_label(t);
			emit_line("\tMOVQ\t$1, AX\n");
			emit_label(e);
			return;
		};
		return;
	};

	if (k == N_BIN) {
		let unsignd: bool = node_isunsigned(c, n.lhs);
		if (!unsignd) { unsignd = node_isunsigned(c, n.rhs); };

		cgexpr(c, n.rhs);
		emit_line("\tPUSHQ\tAX\n");
		cgexpr(c, n.lhs);
		emit_line("\tPOPQ\tBX\n");
		if (n.op == TK_PLUS)    { emit_line("\tADDQ\tBX, AX\n"); return; };
		if (n.op == TK_MINUS)   { emit_line("\tSUBQ\tBX, AX\n"); return; };
		if (n.op == TK_STAR)    { emit_line("\tIMULQ\tBX, AX\n"); return; };
		if (n.op == TK_SLASH) {
			emit_line("\tMOVQ\t$0, DX\n");
			if (unsignd) { emit_line("\tDIVQ\tBX\n"); }
			else         { emit_line("\tIDIVQ\tBX\n"); };
			return;
		};
		if (n.op == TK_PERCENT) {
			emit_line("\tMOVQ\t$0, DX\n");
			if (unsignd) { emit_line("\tDIVQ\tBX\n"); }
			else         { emit_line("\tIDIVQ\tBX\n"); };
			emit_line("\tMOVQ\tDX, AX\n");
			return;
		};
		if (n.op == TK_AMP)   { emit_line("\tANDQ\tBX, AX\n"); return; };
		if (n.op == TK_PIPE)  { emit_line("\tORQ\tBX, AX\n");  return; };
		if (n.op == TK_CARET) { emit_line("\tXORQ\tBX, AX\n"); return; };
		if (n.op == TK_LSHIFT) {
			emit_line("\tMOVQ\tBX, CX\n");
			emit_line("\tSHLQ\tCX, AX\n");
			return;
		};
		if (n.op == TK_RSHIFT) {
			emit_line("\tMOVQ\tBX, CX\n");
			emit_line("\tSHRQ\tCX, AX\n");
			return;
		};
		if (n.op == TK_AND) { emit_line("\tANDQ\tBX, AX\n"); return; };
		if (n.op == TK_OR)  { emit_line("\tORQ\tBX, AX\n");  return; };

		// Comparison: emit CMPQ, jump on signed/unsigned variant,
		// materialise 0/1 in AX. Same shape as the C cgen.
		let is_cmp: bool = false;
		let jcc: str = "";
		if (n.op == TK_EQ)  { is_cmp = true; jcc = "JE"; };
		if (n.op == TK_NEQ) { is_cmp = true; jcc = "JNE"; };
		if (n.op == TK_LT)  { is_cmp = true; if (unsignd) { jcc = "JB"; } else { jcc = "JL"; }; };
		if (n.op == TK_LE)  { is_cmp = true; if (unsignd) { jcc = "JBE"; } else { jcc = "JLE"; }; };
		if (n.op == TK_GT)  { is_cmp = true; if (unsignd) { jcc = "JA"; } else { jcc = "JG"; }; };
		if (n.op == TK_GE)  { is_cmp = true; if (unsignd) { jcc = "JAE"; } else { jcc = "JGE"; }; };
		if (is_cmp) {
			let t: str = mklabel(c, "ct");
			let e: str = mklabel(c, "ce");
			emit_line("\tCMPQ\tBX, AX\n");
			emit_line("\t"); emit_line(jcc); emit_line("\t"); emit_line(t); emit_line("\n");
			emit_line("\tMOVQ\t$0, AX\n");
			emit_line("\tJMP\t"); emit_line(e); emit_line("\n");
			emit_label(t);
			emit_line("\tMOVQ\t$1, AX\n");
			emit_label(e);
			return;
		};
		return;
	};

	if (k == N_CALL) {
		let nargs: i32 = push_args_rev(c, n.list);
		let i: i32 = 0;
		for (i < nargs) {
			emit_line("\tPOPQ\t");
			emit_line(argreg_name(i));
			emit_line("\n");
			i += 1;
		};
		let callee: *node = n.lhs;
		let callee_name: str;
		callee_name.ptr = nil; callee_name.len = 0;
		// Detect fn-pointer field call: `w.emit(args)` where `w` is
		// a struct local and `emit` is an N_TFN field. Load the
		// field value into AX and CALL through it. Also detect a
		// bare `fp(args)` where `fp` is a local holding a function
		// pointer — mirror C cgen's localfind dispatch (commit
		// 635818e). Without this the call emits `CALL fp(SB)` and
		// the linker rightly fails.
		let is_fnptr_call: bool = false;
		if (callee != nil) {
			if (callee.kind == N_IDENT) {
				let cn: str = callee.str;
				if (local_find_node(c, cn) != nil) {
					is_fnptr_call = true;
				};
			};
			if (callee.kind == N_DOT) {
				let base: *node = callee.lhs;
				let fld: str = callee.str;
				if (base != nil) {
					if (base.kind == N_IDENT) {
						let bn: str = base.str;
						let lc: *local = local_find_node(c, bn);
						if (lc != nil) {
							let tn: *node = lc.tnode;
							if (tn != nil) {
								let lkind: i32 = tn.kind;
								let sname: str;
								sname.ptr = nil; sname.len = 0;
								if (lkind == N_TNAME) { sname = tn.str; };
								if (lkind == N_TPTR) {
									let inner: *node = tn.lhs;
									if (inner != nil) {
										if (inner.kind == N_TNAME) { sname = inner.str; };
									};
								};
								if (sname.len > 0) {
									let si: *struct_info = struct_lookup(c, sname);
									if (si != nil) {
										let fi: *field_info = si.fields;
										for (fi != nil) {
											let fn_: str = fi.fname;
											if (streq(fn_, fld)) {
												let ft: *node = fi.tnode;
												if (ft != nil) {
													if (ft.kind == N_TFN) {
														is_fnptr_call = true;
													};
												};
												fi = nil;
											} else {
												fi = fi.finext;
											};
										};
									};
								};
							};
						};
					};
				};
			};
		};
		if (is_fnptr_call) {
			// Load fn-ptr field value into AX; CALL AX. We emit the
			// load AFTER the args have been popped (so AX/BX/etc
			// don't get clobbered by the field load before the pops).
			// `popped args` left DI/SI/etc set; AX is free.
			cgexpr(c, callee);
			emit_line("\tCALL\tAX\n");
		} else {
			emit_line("\tCALL\t");
			if (callee != nil) {
				if (callee.kind == N_IDENT) {
					callee_name = callee.str;
					let resolved: str = ffi_resolve(c, callee_name);
					os.write(1, resolved.ptr, resolved.len: u64);
				} else { if (callee.kind == N_DOT) {
					callee_name = callee.str;
					let resolved: str = ffi_resolve(c, callee_name);
					os.write(1, resolved.ptr, resolved.len: u64);
				};};
			};
			emit_line("(SB)\n");
		};
		// SysV returns 16-byte aggregates in (AX, DX). Our str
		// convention is (AX, BX), so shuffle for str-returning calls.
		if (callee_name.len > 0) {
			let rt: *node = fnret_lookup(c, callee_name);
			if (is_str_type(c, rt)) {
				emit_line("\tMOVQ\tDX, BX\n");
			};
		};
		return;
	};

	if (k == N_ASSIGN) {
		let lhs: *node = n.lhs;
		// `*p = v` — deref-assign. Element width comes from the
		// pointer's declared type. Mirrors C cgen: eval rhs (AX,
		// and BX if str), push, eval pointer, pop value, store.
		// We default to MOVQ (8B) since most fixtures use it; for
		// `*bool` / `*u8` / `*i32` we narrow via the local's tnode.
		if (lhs != nil) {
			if (lhs.kind == N_UN) {
				if (lhs.op == TK_STAR) {
					if (n.op == TK_ASSIGN) {
						let inner: *node = lhs.lhs;
						let elem_str: bool = false;
						let store_op: str = "MOVQ";
						if (inner != nil) {
							if (inner.kind == N_IDENT) {
								let lc: *local = local_find_node(c, inner.str);
								if (lc != nil) {
									let tn: *node = lc.tnode;
									if (tn != nil) {
										if (tn.kind == N_TPTR) {
											let pe: *node = tn.lhs;
											if (pe != nil) {
												if (pe.kind == N_TNAME) {
													if (streq(pe.str, "str")) { elem_str = true; }
													else {
														let ps: i32 = prim_size(pe.str);
														if (ps == 1) { store_op = "MOVB"; }
														else { if (ps == 4) { store_op = "MOVL"; }; };
													};
												};
											};
										};
									};
								};
							};
						};
						cgexpr(c, n.rhs);
						// Push order matches C cgen
						// (cmd/6c/cgen.c:1033-1041): PUSHQ AX
						// (ptr) first, then PUSHQ BX (len) if
						// str, so the pop sequence is POP CX
						// (len) → POP AX (ptr) → MOVQ AX,
						// (BX) → MOVQ CX, 8(BX).
						emit_line("\tPUSHQ\tAX\n");
						if (elem_str) { emit_line("\tPUSHQ\tBX\n"); };
						cgexpr(c, inner);
						emit_line("\tMOVQ\tAX, BX\n");
						if (elem_str) {
							emit_line("\tPOPQ\tCX\n");
							emit_line("\tPOPQ\tAX\n");
							emit_line("\tMOVQ\tAX, (BX)\n");
							emit_line("\tMOVQ\tCX, 8(BX)\n");
							return;
						};
						emit_line("\tPOPQ\tAX\n");
						emit_line("\t");
						emit_line(store_op);
						emit_line("\tAX, (BX)\n");
						return;
					};
				};
			};
		};
		// Array/slice/ptr index store: `arr[i] = v;`. Element size
		// from base.tnode picks MOVB vs MOVQ.
		if (lhs != nil) {
			if (lhs.kind == N_INDEX) {
				if (n.op == TK_ASSIGN) {
					let base: *node = lhs.lhs;
					let idx: *node = lhs.rhs;
					let esz: i32 = 8;
					let base_local: *local = nil;
					if (base != nil) {
						if (base.kind == N_IDENT) {
							let bn: str = base.str;
							base_local = local_find_node(c, bn);
							if (base_local != nil) {
								esz = elem_size_of(base_local.tnode);
							};
						} else { if (base.kind == N_DOT) {
							esz = index_base_esz(c, base);
						};};
					};
					cgexpr(c, n.rhs);            // value → AX
						if (esz == 16) { emit_line("\tPUSHQ\tBX\n"); };
					emit_line("\tPUSHQ\tAX\n");
					cgexpr(c, idx);              // idx → AX
					if (esz > 1) {
						emit_line("\tMOVQ\t$");
						emit_int(esz: i64);
						emit_line(", CX\n");
						emit_line("\tIMULQ\tCX, AX\n");
					};
					emit_line("\tPUSHQ\tAX\n");  // scaled idx
					if (base_local != nil) {
						let tn: *node = base_local.tnode;
						let is_array: bool = false;
						if (tn != nil) { if (tn.kind == N_TARRAY) { is_array = true; }; };
						if (is_array) {
							emit_line("\tLEAQ\t");
							emit_off(base_local.off: i64);
							emit_line("(BP), BX\n");
						} else {
							emit_line("\tMOVQ\t");
							emit_off(base_local.off: i64);
							emit_line("(BP), BX\n");
						};
					} else {
						cgexpr(c, base);
						emit_line("\tMOVQ\tAX, BX\n");
					};
					emit_line("\tPOPQ\tAX\n");   // scaled idx
					emit_line("\tADDQ\tAX, BX\n");
					emit_line("\tPOPQ\tAX\n");   // value
						if (esz == 16) {
							emit_line("\tMOVQ\tAX, (BX)\n");
							emit_line("\tPOPQ\tCX\n");
							emit_line("\tMOVQ\tCX, 8(BX)\n");
							return;
						};
					if (esz == 1) { emit_line("\tMOVB\tAX, (BX)\n"); }
					else          { emit_line("\tMOVQ\tAX, (BX)\n"); };
					return;
				};
			};
		};
		// Struct/ptr-to-struct field assignment: `s.f = expr;` or
		// `p.f = expr;`. Only plain `=` is wired (compound on field
		// is rare and not yet needed by our fixtures).
		if (lhs != nil) {
			if (lhs.kind == N_DOT) {
				let base: *node = lhs.lhs;
				let fld: str = lhs.str;
				if (base != nil) {
					if (base.kind == N_IDENT) {
						let bn: str = base.str;
						let lc: *local = local_find_node(c, bn);
						if (lc != nil) {
							let tn: *node = lc.tnode;
							let lkind: i32 = -1;
							if (tn != nil) { lkind = tn.kind; };
							// Pointer-to-struct: deref then store.
							if (lkind == N_TPTR) {
								let inner: *node = tn.lhs;
								let sname: str;
								sname.ptr = nil; sname.len = 0;
								if (inner != nil) {
									if (inner.kind == N_TNAME) { sname = inner.str; };
								};
								if (sname.len > 0) {
									let si: *struct_info = struct_lookup(c, sname);
									if (si != nil) {
										let fi: *field_info = si.fields;
										for (fi != nil) {
											let fn_: str = fi.fname;
											if (streq(fn_, fld)) {
												if (n.op != TK_ASSIGN) {
													// compound: load current value
													emit_line("\tMOVQ\t");
													emit_off(lc.off: i64);
													emit_line("(BP), BX\n");
													let lop: str = field_load_op(fi);
													emit_line("\t");
													emit_line(lop);
													emit_line("\t");
													emit_disp_reg(fi.foff: i64, "BX");
													emit_line(", BX\n");
													emit_line("\tPUSHQ\tBX\n");
												};
												cgexpr(c, n.rhs);
												if (n.op != TK_ASSIGN) {
													emit_line("\tPOPQ\tBX\n");
													// PLUSEQ is commutative; MINUSEQ
													// needs lhs - rhs (BX is old lhs,
													// AX is rhs).
													if (n.op == TK_PLUSEQ)  { emit_line("\tADDQ\tBX, AX\n"); };
													if (n.op == TK_MINUSEQ) {
														emit_line("\tSUBQ\tAX, BX\n");
														emit_line("\tMOVQ\tBX, AX\n");
													};
												};
												// str field via *struct: rhs left
												// (AX=ptr, BX=len). Use CX as the
												// address scratch so we don't clobber
												// the len half before storing it.
												if (n.op == TK_ASSIGN) {
													if (is_str_type(c, fi.tnode)) {
														emit_line("\tMOVQ\t");
														emit_off(lc.off: i64);
														emit_line("(BP), CX\n");
														emit_line("\tMOVQ\tAX, ");
														emit_disp_reg(fi.foff: i64, "CX");
														emit_line("\n");
														emit_line("\tMOVQ\tBX, ");
														emit_disp_reg((fi.foff + 8): i64, "CX");
														emit_line("\n");
														return;
													};
												};
												emit_line("\tMOVQ\t");
												emit_off(lc.off: i64);
												emit_line("(BP), BX\n");
												let sop: str = field_store_op(fi);
												emit_line("\t");
												emit_line(sop);
												emit_line("\tAX, ");
												emit_disp_reg(fi.foff: i64, "BX");
												emit_line("\n");
												return;
											};
											fi = fi.finext;
										};
									};
								};
							};
								// Direct struct local: store at off+foff.
								if (lkind == N_TNAME) {
									let sname: str = tn.str;
									let si: *struct_info = struct_lookup(c, sname);
									if (si != nil) {
										let fi: *field_info = si.fields;
										for (fi != nil) {
											let fn_: str = fi.fname;
											if (streq(fn_, fld)) {
												cgexpr(c, n.rhs);
												let sop: str = field_store_op(fi);
												emit_line("\t");
												emit_line(sop);
												emit_line("\tAX, ");
												emit_off((lc.off + fi.foff): i64);
												emit_line("(BP)\n");
												return;
											};
											fi = fi.finext;
										};
									};
								};
								// str/slice pseudo-field assignment.
								let delta: i32 = -1;
								if (streq(fld, "ptr")) { delta = 0; };
								if (streq(fld, "len")) { delta = 8; };
								if (streq(fld, "cap")) { delta = 16; };
								if (delta >= 0) {
									if (lkind == N_TPTR) {
										let inner: *node = tn.lhs;
										let inner_kind: i32 = -1;
										if (inner != nil) { inner_kind = inner.kind; };
										let inner_str: bool = false;
										if (inner_kind == N_TNAME) {
											if (streq(inner.str, "str")) { inner_str = true; };
										};
										if (inner_kind == N_TSLICE) { inner_str = true; };
										if (inner_str) {
											if (n.op != TK_ASSIGN) {
												// Compound on `(*str|*slice).field`: load
												// current → push → eval rhs → combine → store.
												emit_line("\tMOVQ\t");
												emit_off(lc.off: i64);
												emit_line("(BP), BX\n");
												emit_line("\tMOVQ\t");
												emit_disp_reg(delta: i64, "BX");
												emit_line(", BX\n");
												emit_line("\tPUSHQ\tBX\n");
												cgexpr(c, n.rhs);
												emit_line("\tPOPQ\tBX\n");
												// PLUSEQ is commutative; MINUSEQ
												// needs lhs - rhs.
												if (n.op == TK_PLUSEQ)  { emit_line("\tADDQ\tBX, AX\n"); };
												if (n.op == TK_MINUSEQ) {
													emit_line("\tSUBQ\tAX, BX\n");
													emit_line("\tMOVQ\tBX, AX\n");
												};
												emit_line("\tMOVQ\t");
												emit_off(lc.off: i64);
												emit_line("(BP), BX\n");
												emit_line("\tMOVQ\tAX, ");
												emit_disp_reg(delta: i64, "BX");
												emit_line("\n");
												return;
											};
											cgexpr(c, n.rhs);
											emit_line("\tMOVQ\t");
											emit_off(lc.off: i64);
											emit_line("(BP), BX\n");
											emit_line("\tMOVQ\tAX, ");
											emit_disp_reg(delta: i64, "BX");
											emit_line("\n");
											return;
										};
									};
									cgexpr(c, n.rhs);
									emit_line("\tMOVQ\tAX, ");
									emit_off((lc.off + delta): i64);
									emit_line("(BP)\n");
									return;
								};
							};
						};
					};
				};
			};
		// Local-ident target — plain `=` and the simple compound
		// forms (+= -= *= /=); other compounds fall back to
		// "evaluate rhs, replace". Mirrors C cgen's IDENT-assign path.
		if (lhs != nil) {
			if (lhs.kind == N_IDENT) {
				let nm: str = lhs.str;
				let off: i32 = local_find(c, nm);
				if (off == 0) { return; };
				// Detect str-typed local — assignment must store both
				// halves (AX=ptr at +0, BX=len at +8).
				let lc_str: bool = false;
				let lcn: *local = local_find_node(c, nm);
				if (lcn != nil) { lc_str = is_str_type(c, lcn.tnode); };
				cgexpr(c, n.rhs);
				if (n.op == TK_ASSIGN) {
					emit_line("\tMOVQ\tAX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
					if (lc_str) {
						emit_line("\tMOVQ\tBX, ");
						emit_off((off + 8): i64);
						emit_line("(BP)\n");
					};
					return;
				};
				if (n.op == TK_PLUSEQ) {
					emit_line("\tADDQ\tAX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
					return;
				};
				if (n.op == TK_MINUSEQ) {
					emit_line("\tSUBQ\tAX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
					return;
				};
				// Generic compound: load → combine in BX → store.
				emit_line("\tMOVQ\t");
				emit_off(off: i64);
				emit_line("(BP), BX\n");
				if (n.op == TK_STAREQ)   { emit_line("\tIMULQ\tAX, BX\n"); };
				if (n.op == TK_AMPEQ)    { emit_line("\tANDQ\tAX, BX\n"); };
				if (n.op == TK_PIPEEQ)   { emit_line("\tORQ\tAX, BX\n"); };
				if (n.op == TK_CARETEQ)  { emit_line("\tXORQ\tAX, BX\n"); };
				if (n.op == TK_LSHIFTEQ) {
					emit_line("\tMOVQ\tAX, CX\n");
					emit_line("\tSHLQ\tCX, BX\n");
				};
				if (n.op == TK_RSHIFTEQ) {
					emit_line("\tMOVQ\tAX, CX\n");
					emit_line("\tSHRQ\tCX, BX\n");
				};
				emit_line("\tMOVQ\tBX, ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				return;
			};
		};
		return;
	};
};

// ---- type-driven slot sizing ----------------------------------------

fn struct_lookup(c: *cgen, name: str) *struct_info = {
	let s: *struct_info = c.structs;
	for (s != nil) {
		let sn: str = s.sname;
		if (streq(sn, name)) { return s; };
		s = s.sinext;
	};
	return nil;
};

// prim_size — size in bytes of a primitive type name (or 0 if not
// recognised as a primitive — the caller falls back to other paths).
fn prim_size(name: str) i32 = {
	if (streq(name, "u8"))   { return 1; };
	if (streq(name, "i8"))   { return 1; };
	if (streq(name, "bool")) { return 1; };
	if (streq(name, "u16"))  { return 2; };
	if (streq(name, "i16"))  { return 2; };
	if (streq(name, "u32"))  { return 4; };
	if (streq(name, "i32"))  { return 4; };
	if (streq(name, "f32"))  { return 4; };
	if (streq(name, "u64"))  { return 8; };
	if (streq(name, "i64"))  { return 8; };
	if (streq(name, "uint")) { return 8; };
	if (streq(name, "int"))  { return 8; };
	if (streq(name, "uintptr")) { return 8; };
	if (streq(name, "f64"))  { return 8; };
	if (streq(name, "rune")) { return 4; };
	if (streq(name, "void")) { return 0; };
	return 0;
};

fn slot_size(c: *cgen, typ_n: *node) i32 = {
	if (typ_n == nil) { return 8; };
	let k: i32 = typ_n.kind;
	if (k == N_TPTR)   { return 8; };
	if (k == N_TFN)    { return 8; };
	if (k == N_TCHAN)  { return 8; };
	if (k == N_TSLICE) { return 24; };
	if (k == N_TTUPLE) { return 16; };
	if (k == N_TTAGGED){ return 24; };
	if (k == N_TNAME) {
		let nm: str = typ_n.str;
		if (streq(nm, "str")) { return 16; };
		let ps: i32 = prim_size(nm);
		if (ps > 0) {
			// Pad to 8 for stack slots — matches C cgen which spills
			// every primitive into an 8-byte slot.
			return 8;
		};
		// Named struct lookup.
		let si: *struct_info = struct_lookup(c, nm);
		if (si != nil) { return si.tot_size; };
		return 8;
	};
	if (k == N_TARRAY) {
		let len_n: *node = typ_n.rhs;
		let elem_n: *node = typ_n.lhs;
		let elen: i64 = 1i64;
		if (len_n != nil) {
			if (len_n.kind == N_INTLIT) { elen = len_n.uval: i64; };
		};
		let esz: i32 = 8;
		if (elem_n != nil) {
			if (elem_n.kind == N_TNAME) {
				let en: str = elem_n.str;
				let ps: i32 = prim_size(en);
				if (ps > 0) { esz = ps; };
			};
		};
		return (esz: i64 * elen): i32;
	};
	if (k == N_TSTRUCT) {
		// Inline anonymous struct — sum of field sizes.
		let f: *node = typ_n.list;
		let total: i32 = 0;
		for (f != nil) {
			if (f.kind == N_TFIELD) {
				total += slot_size(c, f.lhs);
			};
			f = f.next;
		};
		return total;
	};
	return 8;
};

// register_struct — compute field offsets + total size for a struct
// type-decl, store in c.structs. Field type sizes use the same
// slot_size logic (with primitives kept at their natural width — we
// only round to 8 for stack slots, not struct interiors).
fn field_size(c: *cgen, tnode: *node) i32 = {
	if (tnode == nil) { return 8; };
	let k: i32 = tnode.kind;
	if (k == N_TNAME) {
		let nm: str = tnode.str;
		if (streq(nm, "str")) { return 16; };
		let ps: i32 = prim_size(nm);
		if (ps > 0) { return ps; };
		let si: *struct_info = struct_lookup(c, nm);
		if (si != nil) { return si.tot_size; };
		return 8;
	};
	if (k == N_TPTR)   { return 8; };
	if (k == N_TSLICE) { return 24; };
	if (k == N_TARRAY) {
		// Same shape as slot_size's TARRAY branch.
		let len_n: *node = tnode.rhs;
		let elem_n: *node = tnode.lhs;
		let elen: i64 = 1i64;
		if (len_n != nil) {
			if (len_n.kind == N_INTLIT) { elen = len_n.uval: i64; };
		};
		let esz: i32 = field_size(c, elem_n);
		return (esz: i64 * elen): i32;
	};
	return 8;
};

fn register_struct(c: *cgen, name: str, tstruct: *node) void = {
	let si: *struct_info = amalloc(c.a, 64u64): *struct_info;
	si.sname = name;
	si.fields = nil;
	si.tot_size = 0;
	let head: *field_info = nil;
	let tail: *field_info = nil;
	let off: i32 = 0;
	let f: *node = tstruct.list;
	for (f != nil) {
		if (f.kind == N_TFIELD) {
			let sz: i32 = field_size(c, f.lhs);
			// Align to 8 for any field >= 4 bytes (matches our other
			// cgen choices). i8/u8/bool may sit on odd byte offsets;
			// the C cgen does similar best-effort packing.
			let aln: i32 = 1;
			if (sz >= 8) { aln = 8; }
			else { if (sz >= 4) { aln = 4; }
			else { if (sz >= 2) { aln = 2; }; }; };
			if ((off & (aln - 1)) != 0) {
				off = (off + aln - 1) & ~(aln - 1);
			};
			let fi: *field_info = amalloc(c.a, 48u64): *field_info;
			fi.fname = f.str;
			fi.foff = off;
			fi.fsz  = sz;
			fi.tnode = f.lhs;
			if (head == nil) { head = fi; tail = fi; }
			else { tail.finext = fi; tail = fi; };
			off += sz;
		};
		f = f.next;
	};
	// Round total to 8 for stack-slot use.
	if ((off & 7) != 0) { off = (off + 7) & ~7; };
	si.fields = head;
	si.tot_size = off;
	si.sinext = c.structs;
	c.structs = si;
};

fn collect_structs(c: *cgen, file: *node) void = {
	c.structs = nil;
	if (file == nil) { return; };
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_TYPEDECL) {
			let body: *node = d.lhs;
			if (body != nil) {
				if (body.kind == N_TSTRUCT) {
					register_struct(c, d.str, body);
				};
			};
		};
		d = d.next;
	};
};

// ---- frame pre-scan --------------------------------------------------
//
// Recursively walks the body to count every local `let`. Each gets a
// slot sized by slot_size(typ); 8-byte default. Match-bindings + for-
// init lets count too. Params are added by the cgfn driver.

fn scan_locals(c: *cgen, n: *node) i32 = {
	if (n == nil) { return 0; };
	let total: i32 = 0;
	if (n.kind == N_LET) {
		// Match local_add's rounding: < 8 bumps to 8, then 8-align.
		// scan_locals must agree with local_add or the prologue
		// SUBQ undersizes the frame and lets overflow into the
		// caller's stack — corrupting whatever's at -frameSize..-1
		// of the caller. Same-name re-declarations share the first
		// slot (see scan_seen_mark / local_add).
		if (!scan_seen_mark(c, n.str)) {
			let sz: i32 = slot_size(c, n.lhs);
			if (sz < 8) { sz = 8; };
			if ((sz & 7) != 0) { sz = (sz + 7) & ~7; };
			total += sz;
		};
	};
	// Match-arm binding (`case let v: T => ...`) gets a slot too.
	// Crucially we do NOT dedup these against c.locals: C cgen
	// handles a match as an expression with a by-value locals copy,
	// so two separate matches in the same function each allocate
	// their `v`/`e` slots fresh. Treating these as deduped would
	// shrink the frame below what local_add then bumps it to.
	if (n.kind == N_MCASE) {
		let bn: str = n.str;
		if (bn.len > 0) {
			let pat: *node = n.lhs;
			if (pat != nil) {
				if (is_str_type(c, pat)) { total += 16; }
				else { total += 8; };
			};
		};
	};
	if (n.lhs  != nil) { total += scan_locals(c, n.lhs);  };
	if (n.rhs  != nil) { total += scan_locals(c, n.rhs);  };
	if (n.cond != nil) { total += scan_locals(c, n.cond); };
	if (n.body != nil) { total += scan_locals(c, n.body); };
	if (n.els  != nil) { total += scan_locals(c, n.els);  };
	if (n.list != nil) {
		let m: *node = n.list;
		for (m != nil) {
			total += scan_locals(c, m);
			m = m.next;
		};
	};
	return total;
};

// ---- statement cgen --------------------------------------------------

fn cgstmt(c: *cgen, n: *node) void = {
	if (n == nil) { return; };
	let k: i32 = n.kind;

	if (k == N_BLOCK) {
		let s: *node = n.list;
		for (s != nil) {
			cgstmt(c, s);
			s = s.next;
		};
		return;
	};

	if (k == N_RETURN) {
		let rhs: *node = n.lhs;
		if (rhs != nil) {
			// Tuple return `return a, b;` — pack as (AX=v0, DX=v1).
			// Matches C cgen: evaluate v1 first (PUSHQ), then v0
			// into AX, then POPQ DX. End state: AX = v0, DX = v1.
			if (rhs.kind == N_TUPLE) {
				let v: *node = rhs.list;
				if (v != nil) {
					let v2: *node = v.next;
					if (v2 != nil) {
						cgexpr(c, v2);
						emit_line("\tPUSHQ\tAX\n");
						cgexpr(c, v);
						emit_line("\tPOPQ\tDX\n");
					} else {
						cgexpr(c, v);
					};
				};
				emit_line("\tMOVQ\tBP, SP\n");
				emit_line("\tPOPQ\tBP\n");
				emit_line("\tRET\n");
				c.last_was_return = 1;
				return;
			};
			// Tagged-union return: pack as (AX=tag, DX=value0, CX=value1).
			// For str variant, cgexpr leaves (AX=ptr, BX=len), so we
			// shuffle DX←AX (ptr) and CX←BX (len), then load tag.
			// For other variants, cgexpr leaves AX, shuffle DX←AX.
			if (is_tagged_type(c.fn_ret)) {
				cgexpr(c, rhs);
				let idx: i32 = tagged_variant_index(c, c.fn_ret, rhs);
				if (node_isstr(c, rhs)) {
					emit_line("\tMOVQ\tBX, CX\n");
					emit_line("\tMOVQ\tAX, DX\n");
				} else {
					emit_line("\tMOVQ\tAX, DX\n");
				};
				emit_line("\tMOVQ\t$");
				if (idx < 0) { idx = 0; };
				emit_int(idx: i64);
				emit_line(", AX\n");
				emit_line("\tMOVQ\tBP, SP\n");
				emit_line("\tPOPQ\tBP\n");
				emit_line("\tRET\n");
				c.last_was_return = 1;
				return;
			};
			cgexpr(c, rhs);
		} else {
			// Bare `return;` in a void fn — zero AX so the caller
			// sees a deterministic value (matches C cgen, which
			// always falls through to `cgexpr_int(c, 0)`).
			emit_line("\tMOVQ\t$0, AX\n");
		};
		// SysV: 16-byte aggregates (str, 2-tuple) return in (AX, DX).
		// cgexpr leaves str in (AX, BX); shuffle BX→DX.
		if (is_str_type(c, c.fn_ret)) {
			emit_line("\tMOVQ\tBX, DX\n");
		};
		emit_line("\tMOVQ\tBP, SP\n");
		emit_line("\tPOPQ\tBP\n");
		emit_line("\tRET\n");
		c.last_was_return = 1;
		return;
	};

	if (k == N_EXPRSTMT) {
		if (n.lhs != nil) { cgexpr(c, n.lhs); };
		c.last_was_return = 0;
		return;
	};

	if (k == N_LET) {
		let nm: str = n.str;
		let sz: i32 = slot_size(c, n.lhs);
		let off: i32 = local_add(c, nm, sz, n.lhs);
		if (n.rhs != nil) {
			let rhs: *node = n.rhs;
			// Tagged-union init: `let r: (T | E) = expr;`.
			//   - If rhs is a CALL to a fn returning tagged-union,
			//     the result is already in (AX=tag, DX=v0, CX=v1);
			//     just spill all three.
			//   - Otherwise rhs is a bare variant value: pack tag +
			//     value(s).
			if (is_tagged_type(n.lhs)) {
				let rhs_returns_tagged: bool = false;
				if (rhs.kind == N_CALL) {
					let callee: *node = rhs.lhs;
					if (callee != nil) {
						let callee_name: str;
						callee_name.ptr = nil; callee_name.len = 0;
						if (callee.kind == N_IDENT) { callee_name = callee.str; };
						if (callee.kind == N_DOT)   { callee_name = callee.str; };
						if (callee_name.len > 0) {
							let rt: *node = fnret_lookup(c, callee_name);
							if (is_tagged_type(rt)) { rhs_returns_tagged = true; };
						};
					};
				};
				cgexpr(c, rhs);
				if (rhs_returns_tagged) {
					emit_line("\tMOVQ\tAX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
					emit_line("\tMOVQ\tDX, ");
					emit_off((off + 8): i64);
					emit_line("(BP)\n");
					emit_line("\tMOVQ\tCX, ");
					emit_off((off + 16): i64);
					emit_line("(BP)\n");
					c.last_was_return = 0;
					return;
				};
				let tag_idx: i32 = tagged_variant_index(c, n.lhs, rhs);
				if (tag_idx < 0) { tag_idx = 0; };
				if (node_isstr(c, rhs)) {
					emit_line("\tMOVQ\tAX, ");
					emit_off((off + 8): i64);
					emit_line("(BP)\n");
					emit_line("\tMOVQ\tBX, ");
					emit_off((off + 16): i64);
					emit_line("(BP)\n");
				} else {
					emit_line("\tMOVQ\tAX, ");
					emit_off((off + 8): i64);
					emit_line("(BP)\n");
				};
				emit_line("\tMOVQ\t$");
				emit_int(tag_idx: i64);
				emit_line(", ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				c.last_was_return = 0;
				return;
			};
			// Struct literal init: `let p: point = point{x=..., y=...};`.
			// For each field in the lit, evaluate its value and store at
			// the field's offset within the slot. Field-name → offset
			// from the struct registry.
			if (rhs.kind == N_STRUCTLIT) {
				let trefn: *node = rhs.lhs;
				let sname: str;
				sname.ptr = nil; sname.len = 0;
				if (trefn != nil) {
					if (trefn.kind == N_IDENT) { sname = trefn.str; }
					else { if (trefn.kind == N_TNAME) { sname = trefn.str; }; };
				};
				let si: *struct_info = struct_lookup(c, sname);
				if (si != nil) {
					let field_node: *node = rhs.list;
					for (field_node != nil) {
						if (field_node.kind == N_FIELD) {
							let fname: str = field_node.str;
							let fi: *field_info = si.fields;
							for (fi != nil) {
								let fn_: str = fi.fname;
								if (streq(fn_, fname)) {
									cgexpr(c, field_node.lhs);
									let sop: str = field_store_op(fi);
									emit_line("\t");
									emit_line(sop);
									emit_line("\tAX, ");
									emit_off((off + fi.foff): i64);
									emit_line("(BP)\n");
									fi = nil;
								} else {
									fi = fi.finext;
								};
							};
						};
						field_node = field_node.next;
					};
					c.last_was_return = 0;
					return;
				};
			};
			cgexpr(c, rhs);
			emit_line("\tMOVQ\tAX, ");
			emit_off(off: i64);
			emit_line("(BP)\n");
			// str init: cgexpr also leaves len in BX; store both.
			if (sz == 16) {
				emit_line("\tMOVQ\tBX, ");
				emit_off((off + 8): i64);
				emit_line("(BP)\n");
			};
			// slice init: ptr/len/cap in AX/BX/CX.
			if (sz == 24) {
				emit_line("\tMOVQ\tBX, ");
				emit_off((off + 8): i64);
				emit_line("(BP)\n");
				emit_line("\tMOVQ\tCX, ");
				emit_off((off + 16): i64);
				emit_line("(BP)\n");
			};
		} else {
			// Bare `let x: T;` with no initializer. C cgen
			// (cmd/6c/cgen.c:2181-2183) zero-inits only when
			// the underlying type's natural size is 8 — pointers,
			// i64/u64, function pointers, ints. Structs/arrays/
			// slices/strings/tagged/tuples are left for per-field
			// writes. ww's slot_size pads struct slots up to 8,
			// so we can't just check sz == 8: walk the type AST
			// directly to make the same call.
			if (type_is_8byte_primitive(c, n.lhs)) {
				emit_line("\tMOVQ\t$0, ");
				emit_off(off: i64);
				emit_line("(BP)\n");
			};
		};
		c.last_was_return = 0;
		return;
	};

	if (k == N_IF) {
		let els: str = mklabel(c, "else");
		let endl: str = mklabel(c, "end");
		cgexpr(c, n.cond);
		emit_line("\tCMPQ\t$0, AX\n");
		emit_line("\tJE\t");
		if (n.els != nil) { emit_line(els); }
		else              { emit_line(endl); };
		emit_line("\n");
		if (n.body != nil) { cgstmt(c, n.body); };
		if (n.els != nil) {
			emit_line("\tJMP\t"); emit_line(endl); emit_line("\n");
			emit_label(els);
			cgstmt(c, n.els);
		};
		emit_label(endl);
		c.last_was_return = 0;
		return;
	};

	if (k == N_FOR) {
		// Match C cgen's label scheme: <fn>_loop_N for the top,
		// <fn>_endloop_N for the post-body merge. No separate cont
		// label when there's no post-expression.
		let topl: str = mklabel(c, "loop");
		let endl: str = mklabel(c, "endloop");

		if (n.lhs != nil) { cgstmt(c, n.lhs); };

		emit_label(topl);
		if (n.cond != nil) {
			cgexpr(c, n.cond);
			emit_line("\tCMPQ\t$0, AX\n");
			emit_line("\tJE\t"); emit_line(endl); emit_line("\n");
		};

		c.loop_end_buf[c.loop_top]  = endl;
		c.loop_cont_buf[c.loop_top] = topl;
		c.loop_top += 1;

		if (n.body != nil) { cgstmt(c, n.body); };

		c.loop_top -= 1;

		if (n.rhs != nil) { cgexpr(c, n.rhs); };
		emit_line("\tJMP\t"); emit_line(topl); emit_line("\n");
		emit_label(endl);
		c.last_was_return = 0;
		return;
	};

	// Tuple-destructure assign: `a, b = call();`. The call's tuple
	// return lands in (AX, DX); push DX to free it, store AX into
	// the first lvalue, then pop DX into the second. Mirrors
	// cmd/6c/cgen.c:2424-2440. Lvalues beyond two are dropped (same
	// as C — no fixture uses >2 today).
	if (k == N_MASSIGN) {
		if (n.rhs != nil) { cgexpr(c, n.rhs); };
		emit_line("\tPUSHQ\tDX\n");
		let l0: *node = n.list;
		let l1: *node = nil;
		if (l0 != nil) { l1 = l0.next; };
		if (l0 != nil) {
			if (l0.kind == N_IDENT) {
				let off: i32 = local_find(c, l0.str);
				if (off != 0) {
					emit_line("\tMOVQ\tAX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
				};
			};
		};
		emit_line("\tPOPQ\tDX\n");
		if (l1 != nil) {
			if (l1.kind == N_IDENT) {
				let off: i32 = local_find(c, l1.str);
				if (off != 0) {
					emit_line("\tMOVQ\tDX, ");
					emit_off(off: i64);
					emit_line("(BP)\n");
				};
			};
		};
		c.last_was_return = 0;
		return;
	};

	if (k == N_BREAK) {
		if (c.loop_top > 0) {
			let lbl: str = c.loop_end_buf[c.loop_top - 1];
			emit_line("\tJMP\t"); emit_line(lbl); emit_line("\n");
		};
		c.last_was_return = 0;
		return;
	};
	if (k == N_CONTINUE) {
		if (c.loop_top > 0) {
			let lbl: str = c.loop_cont_buf[c.loop_top - 1];
			emit_line("\tJMP\t"); emit_line(lbl); emit_line("\n");
		};
		c.last_was_return = 0;
		return;
	};

	c.last_was_return = 0;
};

// ---- function-level cgen ---------------------------------------------

// is_str_type — true when the type expr resolves (through any
// `type X = str;` aliases) to `str`. Takes *cgen so it can walk the
// alias chain registered at file load.
fn is_str_type_raw(t: *node) bool = {
	if (t == nil) { return false; };
	if (t.kind == N_TNAME) {
		let nm: str = t.str;
		if (streq(nm, "str")) { return true; };
	};
	return false;
};

fn is_str_type(c: *cgen, t: *node) bool = {
	if (is_str_type_raw(t)) { return true; };
	if (c == nil) { return false; };
	let r: *node = resolve_type(c, t);
	return is_str_type_raw(r);
};

fn is_slice_type_raw(t: *node) bool = {
	if (t == nil) { return false; };
	if (t.kind == N_TSLICE) { return true; };
	return false;
};

fn is_slice_type(c: *cgen, t: *node) bool = {
	if (is_slice_type_raw(t)) { return true; };
	if (c == nil) { return false; };
	let r: *node = resolve_type(c, t);
	return is_slice_type_raw(r);
};

fn is_tagged_type(t: *node) bool = {
	if (t == nil) { return false; };
	if (t.kind == N_TTAGGED) { return true; };
	return false;
};

// rhs_target_name — for a returned value, what's its declared (or
// surface-inferred) type name? `expr: T` casts dictate T directly;
// bare strlit/intlit fall back to a primitive name.
fn rhs_target_name(c: *cgen, rhs: *node) str = {
	let nm: str;
	nm.ptr = nil; nm.len = 0;
	if (rhs == nil) { return nm; };
	if (rhs.kind == N_CAST) {
		let t: *node = rhs.rhs;
		if (t != nil) {
			if (t.kind == N_TNAME) { return t.str; };
		};
		return nm;
	};
	if (rhs.kind == N_STRLIT) { return "str"; };
	if (rhs.kind == N_IDENT) {
		let lc: *local = local_find_node(c, rhs.str);
		if (lc != nil) {
			let tn: *node = lc.tnode;
			if (tn != nil) {
				if (tn.kind == N_TNAME) { return tn.str; };
			};
		};
	};
	return nm;
};

// tagged_variant_index — given the tagged-union type expr and the
// returned value's surface type, find the matching variant's 0-based
// index. Compare by exact type name first; if no match, fall back to
// "any str-shape variant matches an str-typed value".
fn tagged_variant_index(c: *cgen, tagged: *node, rhs: *node) i32 = {
	if (tagged == nil) { return -1; };
	if (rhs == nil)    { return -1; };
	let want_name: str = rhs_target_name(c, rhs);
	if (want_name.len > 0) {
		let v: *node = tagged.list;
		let idx: i32 = 0;
		for (v != nil) {
			if (v.kind == N_TNAME) {
				if (streq(v.str, want_name)) { return idx; };
			};
			v = v.next;
			idx += 1;
		};
	};
	// Fallback: by str-shape (resolves aliases).
	let want_str: bool = node_isstr(c, rhs);
	let v: *node = tagged.list;
	let idx: i32 = 0;
	for (v != nil) {
		let v_is_str: bool = false;
		if (v.kind == N_TNAME) {
			if (is_str_type(c, v)) { v_is_str = true; };
		};
		if (v_is_str == want_str) { return idx; };
		v = v.next;
		idx += 1;
	};
	return -1;
};

fn cgfn_params(c: *cgen, params: *node) void = {
	let p: *node = params;
	let idx: i32 = 0;
	for (p != nil) {
		if (p.kind == N_PARAM) {
			let nm: str = p.str;
			if (is_tagged_type(p.lhs)) {
				// tagged-union param: passed in 3 regs (tag, v0, v1),
				// 24-byte slot.
				let off: i32 = local_add(c, nm, 24, p.lhs);
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				idx += 1;
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off((off + 8): i64);
				emit_line("(BP)\n");
				idx += 1;
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off((off + 16): i64);
				emit_line("(BP)\n");
				idx += 1;
			} else { if (is_slice_type(c, p.lhs)) {
				// slice param: 3 regs (ptr, len, cap), 24-byte slot.
				let off: i32 = local_add(c, nm, 24, p.lhs);
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				idx += 1;
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off((off + 8): i64);
				emit_line("(BP)\n");
				idx += 1;
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off((off + 16): i64);
				emit_line("(BP)\n");
				idx += 1;
			} else { if (is_str_type(c, p.lhs)) {
				// str param: passed in two regs (ptr, len).
				// Slot is 16 bytes; ptr at off+0, len at off+8.
				let off: i32 = local_add(c, nm, 16, p.lhs);
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				idx += 1;
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off((off + 8): i64);
				emit_line("(BP)\n");
				idx += 1;
			} else {
				let off: i32 = local_add(c, nm, 8, p.lhs);
				emit_line("\tMOVQ\t");
				emit_line(argreg_name(idx));
				emit_line(", ");
				emit_off(off: i64);
				emit_line("(BP)\n");
				idx += 1;
			};};};
		};
		p = p.next;
	};
};

fn cgfn(c: *cgen, fn_: *node) void = {
	cgen_init(c, c.a);
	c.fn_name = fn_.str;
	c.fn_ret  = fn_.lhs;

	emit_line("TEXT ");
	let nm: str = fn_.str;
	os.write(1, nm.ptr, nm.len: u64);
	emit_line(",$");

	// Pre-scan total frame: 24 bytes per slice param, 16 per str
	// param, 8 per other param, plus per-let from scan_locals.
	// Seed c.locals with param-name stubs so scan_locals dedups a
	// re-declared `let <name>` in the body against the param's
	// slot (matches C cgen). Stubs get cleared before emission.
	let scan_p: *node = fn_.list;
	let frame: i32 = 0;
	for (scan_p != nil) {
		if (scan_p.kind == N_PARAM) {
			if (is_tagged_type(scan_p.lhs)) { frame += 24; }
			else { if (is_slice_type(c, scan_p.lhs)) { frame += 24; }
			else { if (is_str_type(c, scan_p.lhs)) { frame += 16; }
			else { frame += 8; }; }; };
			scan_seen_mark(c, scan_p.str);
		};
		scan_p = scan_p.next;
	};
	if (fn_.body != nil) { frame += scan_locals(c, fn_.body); };
	// Drop the stubs so emission rebuilds c.locals with real offsets.
	c.locals = nil;
	if ((frame & 15) != 0) {
		frame = (frame + 15) & ~15;
	};
	emit_int(frame: i64);
	emit_line("\n");

	emit_line("\tPUSHQ\tBP\n");
	emit_line("\tMOVQ\tSP, BP\n");
	emit_line("\tSUBQ\t$");
	emit_int(frame: i64);
	emit_line(", SP\n");

	cgfn_params(c, fn_.list);
	c.last_was_return = 0;
	if (fn_.body != nil) { cgstmt(c, fn_.body); };

	if (c.last_was_return == 0) {
		// Zero AX before the fall-through return — matches C cgen,
		// which always emits this so void-returning fns don't leak
		// a stale callee value to their caller.
		emit_line("\tMOVQ\t$0, AX\n");
		emit_line("\tMOVQ\tBP, SP\n");
		emit_line("\tPOPQ\tBP\n");
		emit_line("\tRET\n");
	};
};

// ---- file-level entry ------------------------------------------------

export fn cg_file(c: *cgen, file: *node) void = {
	if (file == nil) { return; };
	c.strlits = nil;
	c.strlit_seq = 0;
	collect_aliases(c, file);
	collect_structs(c, file);
	collect_defs(c, file);
	collect_fnrets(c, file);
	ffi_collect(c, file);
	let d: *node = file.list;
	for (d != nil) {
		if (d.kind == N_FNDECL) {
			if (d.body != nil) {
				cgfn(c, d);
			};
		};
		d = d.next;
	};
	emit_data_section(c);
	emit_def_constants(c, file);
};

// selfhost/cmd/wwdump/main.ww — ww-side port of cmd/wwdump/main.c.
//
// Reads a .ww file, runs the ww-side lexer, prints tokens through
// the ww-side tokprint. The 990_selfhost test diffs this output
// byte-for-byte against the C-side wwdump on the same file. Any
// divergence is a port bug in lex.ww or tok.ww.
//
// Modes:
//   wwdump -t file.ww   tokens (default)
//   wwdump -a file.ww   AST  (not yet implemented; reserved)

use os;
use mem;
use tok;
use lex;
use ast;
use parse;
use typ;
use sym;
use check;
use cgen;
use strconv;

// ---- argv helpers -----------------------------------------------------

// argstrlen — strlen on a NUL-terminated *u8. argv strings are always
// NUL-terminated (kernel-supplied) so this is safe.
fn argstrlen(s: *u8) i32 = {
	let n: i32 = 0;
	for (s[n] != 0u8) { n += 1; };
	return n;
};

fn argstr(p: *u8) str = {
	let s: str;
	s.ptr = p;
	s.len = argstrlen(p);
	return s;
};

// streq_lit — compare a NUL-terminated argv entry to a string literal.
fn streq_lit(p: *u8, lit: str) bool = {
	let i: i32 = 0;
	for (i < lit.len) {
		if (p[i] != lit[i]) { return false; };
		i += 1;
	};
	return p[i] == 0u8;
};

// ---- main -------------------------------------------------------------

export fn main(argc: i32, argv: **u8) i32 = {
	let mode: i32 = 116;	// 't'
	let path: *u8 = nil;
	let i: i32 = 1;
	for (i < argc) {
		let a: *u8 = argv[i];
		if (streq_lit(a, "-t")) {
			mode = 116;
		} else { if (streq_lit(a, "-a")) {
			mode = 97;	// 'a'
		} else { if (streq_lit(a, "-r")) {
			mode = 114;	// 'r' — resolve / name-check
		} else { if (streq_lit(a, "-c")) {
			mode = 99;	// 'c' — codegen / emit asm
		} else { if (path == nil) {
			path = a;
		};};};};};
		i += 1;
	};
	if (path == nil) {
		os.write(2, "usage: wwdump [-t|-a] file.ww\n".ptr, 30u64);
		return 2;
	};

	let fd_or_err: (i32 | str) = os.tryopen(path, os.O_RDONLY, 0i32);
	let fd: i32 = -1;
	match (fd_or_err) {
		case let v: i32 => fd = v;
		case let e: str => {
			os.write(2, "wwdump: cannot open ".ptr, 20u64);
			os.write(2, path, argstrlen(path): u64);
			os.write(2, "\n".ptr, 1u64);
			return 1;
		};
	};

	let sz: i64 = os.filesize(fd);
	if (sz < 0i64) {
		os.write(2, "wwdump: filesize failed\n".ptr, 24u64);
		os.close(fd);
		return 1;
	};

	let a: *arena = newarena();
	let buf: *u8 = amalloc(a, sz: u64): *u8;
	let r: i64 = os.readfull(fd, buf, sz: u64);
	os.close(fd);
	if (r != sz) {
		os.write(2, "wwdump: short read\n".ptr, 19u64);
		return 1;
	};

	let l: lex;
	lexinit(&l, a, argstr(path), buf, sz: u64);

	if (mode == 116) {	// '-t'
		for (true) {
			let t: tok;
			lexnext(&l, &t);
			tokprint(1i32, &t);
			if (t.kind == TK_EOF) { break; };
			if (t.kind == TK_ERR) { break; };
		};
	} else { if (mode == 97) {	// '-a'
		let ps: parser;
		parserinit(&ps, a, &l);
		let f: *node = parsefile(&ps);
		astprint(1i32, f);
	} else { if (mode == 114) {	// '-r' — name resolve report
		let ps: parser;
		parserinit(&ps, a, &l);
		let f: *node = parsefile(&ps);
		let tc: tctx;
		typesinit(&tc, a);
		let ck: checker;
		check_init(&ck, a, &tc);
		// Quiet by default; flip to 1 when debugging missing names.
		ck.verbose = 0;
		check_file(&ck, f);
		// (close out the if-else chain — we'll close all braces below)
		// "<file>: <resolved>/<resolved+unresolved> resolved"
		os.write(1, argstr(path).ptr, argstrlen(path): u64);
		os.write(1, ": ".ptr, 2u64);
		let buf: [32]u8;
		let n: i32 = strconv.i64toa(buf[0:32], ck.nresolved: i64);
		os.write(1, buf.ptr, n: u64);
		os.write(1, "/".ptr, 1u64);
		let total: i32 = ck.nresolved + ck.nunresolved;
		n = strconv.i64toa(buf[0:32], total: i64);
		os.write(1, buf.ptr, n: u64);
		os.write(1, " resolved\n".ptr, 10u64);
		if (ck.nunresolved > 0) { return 1; };
	} else { if (mode == 99) {	// '-c' — codegen / emit asm
		let ps: parser;
		parserinit(&ps, a, &l);
		let f: *node = parsefile(&ps);
		let cg: cgen;
		cgen_init(&cg, a);
		cg_file(&cg, f);
	};};};};

	if (l.errs > 0) { return 1; };
	return 0;
};