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cstage+selfhost+test: fix (*p).f silent drop in N_DOT lhs (read+write)

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Pre-existing landmine surfaced by #5 (whole-STRUCT N_ASSIGN). Both
stages' N_DOT dispatch gated on `lhs->lhs->kind == N_IDENT`; the
parser produces N_UN(STAR, IDENT(p)) for `(*p).f`, so both sides fell
off:
  - Write side (cgassign N_DOT base): emitted nothing, store dropped.
  - Read side (case N_DOT pointer-auto-deref): cgexpr derefed the
    pointer as a scalar, AX = first qword of struct, field offset
    dropped.

Fix: retarget base / dot_lhs to the inner IDENT when shape is
N_UN(STAR, IDENT). The existing via_ptr branch fires identically to
`p.f`. v1 scope is bare-IDENT inner only; `(*expr).f` (non-IDENT
pointer expression) is tracked separately as task #19.

702 covers 7 rows: write_i64/i32/str, read_i64/i32/str_len, roundtrip
This commit is contained in:
Hojun-Cho
2026-05-15 18:13:02 +09:00
parent f24fc113a7
commit c4347499ee
6 changed files with 456 additions and 21 deletions
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40
selfhost/cmd/wwdump/main.combined.ww
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@@ -9825,6 +9825,26 @@ fn cgmatch(c: *cgen, n: *node) void = {
fn cgdot(c: *cgen, n: *node) void = {
let lhs: *node = n.lhs;
let fld: str = n.str;
// `(*p).f` read retarget: parser produces n.lhs = N_UN(STAR,
// IDENT(p)). Substitute the inner IDENT as dotlhs so the
// pointer-auto-deref branch (lhs.kind == N_IDENT && N_TPTR
// tnode) fires the same as `p.f`. Mirror of the N_ASSIGN N_DOT
// lhs retarget in cgassign. v1 scope: N_IDENT inner only;
// (*expr).f follow-up task pending. Enum-leaf lookup above and
// chained-N_DOT branches below keep checking raw lhs since
// (*p) is neither shape.
let dotlhs: *node = lhs;
if (dotlhs != nil) {
if (dotlhs.kind == nkind.N_UN) {
if (dotlhs.op == tkind.TK_STAR) {
if (dotlhs.lhs != nil) {
if (dotlhs.lhs.kind == nkind.N_IDENT) {
dotlhs = dotlhs.lhs;
};
};
};
};
};
// Enum member access: `EnumName.MEMBER` or `pkg.EnumName.MEMBER`
// → inline the pre-computed constant. With driver-side
// concatenation, both forms key off the leaf type name.
@@ -9854,9 +9874,9 @@ fn cgdot(c: *cgen, n: *node) void = {
};
};
};
if (lhs != nil) {
if (lhs.kind == nkind.N_IDENT) {
let nm: str = lhs.str;
if (dotlhs != nil) {
if (dotlhs.kind == nkind.N_IDENT) {
let nm: str = dotlhs.str;
let lc: *local = localfindnode(c, nm);
if (lc != nil) {
let tn: *node = lc.tnode;
@@ -12362,12 +12382,24 @@ fn cgassign(c: *cgen, n: *node) void = {
};
// 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).
// is rare and not yet needed by our fixtures). Base accepts the
// explicit-deref form `(*p).f = ...` (parser N_UN(STAR, IDENT))
// by retargeting to the inner IDENT so the via_ptr branch fires
// the same as auto-deref `p.f = v`. v1 scope: bare-IDENT inner.
if (lhs != nil) {
if (lhs.kind == nkind.N_DOT) {
let base: *node = lhs.lhs;
let fld: str = lhs.str;
if (base != nil) {
if (base.kind == nkind.N_UN) {
if (base.op == tkind.TK_STAR) {
if (base.lhs != nil) {
if (base.lhs.kind == nkind.N_IDENT) {
base = base.lhs;
};
};
};
};
if (base.kind == nkind.N_IDENT) {
let bn: str = base.str;
let lc: *local = localfindnode(c, bn);