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wwstage: make the cgdot alias-peel struct-break module-aware (#223)

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The wwstage cgdot #191 alias-peel loop broke on a name-keyed any-module
structlookup, so a receiver whose alias name collides with a struct of the
same name in ANOTHER module resolved to the foreign struct and fell through to
an undefined `name(SB)` global instead of the field load. The eFinal FLIP
renames io's `vstream` -> `stream`, which collides with memio's `stream`
struct, so io.read/io.write/io.close's `match (s.reader)` emitted
`MOVQ reader(SB), AX` (reader is also a type-alias) -> cs != ww (cstage chases
the nominal TY_NAMED.under pointer chain, module-correct). Gate-blind: on
master both stages emit the same wrong store so byte-id stays green; the FLIP
corpus is the first to put the io-alias/memio-struct collision in one build.

Fix (wwstage-only align-down; cstage is the authority and is untouched): make
the peel's struct-break MODULE-AWARE — break only on a same-module struct (a
genuine struct-value receiver); a same-module alias keeps peeling to its
underlying (io.stream -> *vtable -> the pointer field-load arm); a foreign leaf
keeps the prior any-module heuristic. New structsamemod / aliassamemod mirror
the same-module-first pass already in structlookup / aliaslookup. This is not a
naive alias-first reorder (which would reintroduce the mirror collision: a
same-module struct plus a foreign same-leaf alias). Peel-only — the direct-
struct arm's broader cross-module same-leaf-STRUCT name-keying is filed as #224.

#208-family (name-keyed resolution dropping to a wrong global) but in cgen, not
the checker; #213 is distinct (cosmetic local-struct-match divergence).

test/wcc/784_xmod_alias_struct_collide_run: collision (cross-module alias-vs-
struct, same leaf), symmetric (guards the same-module-struct break against a
naive reorder), and a no-collision control — branched callee. The discriminating
net is cs.s == ww.s (the path is gate-blind and cstage is correct, so byte-id
flips when wwstage is fixed); confirmed by source-revert. The FLIP's combined.ww
is now cs.s == ww.s byte-identical.
This commit is contained in:
Hojun-Cho
2026-05-30 02:00:07 +09:00
parent 1175711021
commit 80184a3acf
7 changed files with 528 additions and 9 deletions
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16
selfhost/cmd/wcc/cgen.ww
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@@ -139,6 +139,22 @@ fn aliaslookup(c: *cgen, name: str) *node = {
return nil;
};
// #223: same-module-ONLY alias resolution. aliaslookup's any-module
// fallback can return a foreign same-leaf alias; the alias-peel in
// cgdot needs to know whether THIS module defines the name as an alias
// (so the peel continues) without that cross-module fallback. Returns
// the alias target only when an alias of `name` lives in c.curmod.
fn aliassamemod(c: *cgen, name: str) *node = {
let a: *aliasent = c.aliases;
for (a != nil) {
if (streq(a.aname, name)) {
if (streq(a.amod, c.curmod)) { return a.target; };
};
a = a.aanext;
};
return nil;
};
// ---- enum registry --------------------------------------------------
//
// Mirrors cmd/wcc/check.c's enum resolution at collect time: walk