ww/test/wcc/841_match_global_field.c

/*
 * 841_match_global_field — match on a tagged-union struct-FIELD of a
 * GLOBAL (module-level) VALUE struct: `match (g.t)`, g a `let g: box`.
 * Task #29.
 *
 * GATE-BLIND both-wrong regression from M1 (#25). M1 added an in-place
 * N_DOT match arm that points the dispatch slot at base.off +
 * field.offset, computing base.off via localfind. For a LOCAL base that
 * is the field's true frame slot ($32 in-place, correct). For a GLOBAL
 * base localfind returns its 0/not-found sentinel, so 0 + field.offset
 * lands in the saved-BP / return-addr region (BP+0/BP+8): both stages
 * emit `MOVQ (BP),AX` and read garbage. Both stages were identical-wrong
 * (byte-id GREEN), so only the RUNTIME oracle catches it — pre-fix
 * match(g.t) returns 213 instead of 42.
 *
 * Fix (both stages, rule 10): gate the in-place arm on a confirmed-LOCAL
 * base. A base is GLOBAL iff localfind(base)==0 && let_islet(base)
 * (cstage) / isletvar(c, base) (wwstage) — the same idiom cstage uses at
 * cgen.c:2000 (also 4707/4730/5393). A global base falls THROUGH to the
 * existing spill `else`, which cgexprs the scrutinee and resolves g(SB)
 * correctly. M1's LOCAL in-place path is unchanged (row (d) pins it).
 *
 * Rows pin the RUNTIME exit code on BOTH driver stages (cstage +
 * wwstage) — the discriminator is the value, not byte-id, since both
 * stages were identical-wrong. A cstage-vs-wwstage asm byte-identity
 * check is kept per row so the symmetric (rule-10) property stays pinned
 * after the guard lands in both stages.
 *   (a) global VALUE-struct int-variant field      [spill, g(SB)]
 *   (b) global field bool->int payload remap        [1-word variant]
 *   (c) global field str-payload (24B box)          [3-word variant]
 *   (d) local VALUE-struct field, in place          [M1 regression guard]
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>

static int
runwait(const char *cmd)
{
	int rc = system(cmd);
	if (rc == -1) return -1;
	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
	return -1;
}

struct row { const char *label; const char *src; int want; };

static const struct row rows[] = {
	/* (a) GLOBAL value struct, field set to the int variant in main,
	 * matched. Pre-fix the in-place arm read BP+0 (213); post-fix the
	 * spill path resolves g(SB) and returns 42. */
	{ "global_field_int",
	  "package main;\n"
	  "type box = struct { t: (int | bool), n: int };\n"
	  "let g: box = box { t = 0, n = 5 };\n"
	  "fn main() i32 = {\n"
	  "    g.t = 42;\n"
	  "    match (g.t) {\n"
	  "    case let n: int => return n: i32;\n"
	  "    case bool => return 1;\n"
	  "    };\n"
	  "};\n",
	  42 },
	/* (b) GLOBAL field reassigned, then matched; the int arm also reads
	 * the sibling field g.n to prove the surrounding global is
	 * undisturbed. Returns 7 + 5 = 12. The static initializer uses the
	 * ZERO payload (t = 0): a nonzero tagged-field payload in a static
	 * struct initializer trips a SEPARATE, deferred static-init DATA
	 * divergence (task #19/#30 — wwstage drops the payload word to 0,
	 * cstage emits it) that is orthogonal to the #29 match-cgen path
	 * exercised here; a zero payload is byte-identical across stages. */
	{ "global_field_reassign_remap",
	  "package main;\n"
	  "type box = struct { t: (int | bool), n: int };\n"
	  "let g: box = box { t = 0, n = 5 };\n"
	  "fn main() i32 = {\n"
	  "    g.t = 7;\n"
	  "    match (g.t) {\n"
	  "    case let n: int => return (n + g.n): i32;\n"
	  "    case bool => return 1;\n"
	  "    };\n"
	  "};\n",
	  12 },
	/* (c) GLOBAL field, 24B str-payload variant (tag@+0, .ptr@+8,
	 * .len@+16). Returns len("hello") = 5. */
	{ "global_field_str_payload_24B",
	  "package main;\n"
	  "type box = struct { t: (str | int), n: int };\n"
	  "let g: box = box { t = 0, n = 5 };\n"
	  "fn main() i32 = {\n"
	  "    g.t = \"hello\";\n"
	  "    match (g.t) {\n"
	  "    case let s: str => return len(s): i32;\n"
	  "    case int => return 99;\n"
	  "    };\n"
	  "};\n",
	  5 },
	/* (d) regression guard: a LOCAL value-struct field still reads in
	 * place (M1's $32 path stays). Returns 42. */
	{ "local_field_inplace_guard",
	  "package main;\n"
	  "type box = struct { t: (int | bool), n: int };\n"
	  "fn main() i32 = {\n"
	  "    let b: box = box { t = 0, n = 5 };\n"
	  "    b.t = 42;\n"
	  "    match (b.t) {\n"
	  "    case let n: int => return n: i32;\n"
	  "    case bool => return 1;\n"
	  "    };\n"
	  "};\n",
	  42 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[64], tmpdir[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/wcmgf_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/wcmgf_%d_d_%d", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s",
	    tmpdir, driver, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[128];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

/* asm_byte_identical — the guard lands in BOTH stages, so cstage vs
 * wwstage text output must stay byte-for-byte identical on every row. */
static int
asm_byte_identical(const char *bin, const struct row *r, int i)
{
	char src[64], cs[64], ws[64], cmd[1024];
	snprintf(src, sizeof src, "/tmp/wcmgf_asm_%d_%d.ww", getpid(), i);
	snprintf(cs,  sizeof cs,  "/tmp/wcmgf_asm_%d_%d_c.s", getpid(), i);
	snprintf(ws,  sizeof ws,  "/tmp/wcmgf_asm_%d_%d_w.s", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	snprintf(cmd, sizeof cmd, "%s/w6c -o %s %s 2>/dev/null", bin, cs, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c errored\n", r->label);
		unlink(src);
		return -1;
	}
	snprintf(cmd, sizeof cmd, "%s/w6c_ww -o %s %s 2>/dev/null",
	    bin, ws, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: w6c_ww errored\n", r->label);
		unlink(src); unlink(cs);
		return -1;
	}

	FILE *fc = fopen(cs, "rb");
	FILE *fw = fopen(ws, "rb");
	int rc = 0;
	if (!fc || !fw) {
		rc = -1;
	} else {
		for (;;) {
			int a = fgetc(fc);
			int b = fgetc(fw);
			if (a != b) { rc = -1; break; }
			if (a == EOF) break;
		}
	}
	if (fc) fclose(fc);
	if (fw) fclose(fw);
	if (rc != 0)
		fprintf(stderr, "row[%s]: cstage vs wwstage asm differs\n",
		    r->label);
	unlink(src); unlink(cs); unlink(ws);
	return rc;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[512];
	if (bin[0] != '/') {
		char cwd[256];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[640];
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

	struct { const char *name; const char *path; int gated_on_existence; }
	drivers[] = {
		{ "cstage",  cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;

	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated_on_existence
		    && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr, "match_global_field: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			int got = run_driver(drivers[d].path, &rows[i], i);
			total++;
			if (got != rows[i].want) {
				fprintf(stderr,
				    "match_global_field[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	if (access(wdrv, X_OK) == 0) {
		for (int i = 0; i < n; i++) {
			total++;
			if (asm_byte_identical(bin, &rows[i], i) != 0)
				fail++;
		}
	}

	if (fail) {
		fprintf(stderr,
		    "match_global_field: %d/%d fixtures failed\n",
		    fail, total);
		return 1;
	}
	printf("match_global_field: %d/%d ok\n", total, total);
	return 0;
}