Hojun-Cho/ww
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

selfhost/cmd/wcc: type-key tagged variant match (#66, Phase-N step 3)

Browse Source 
The user-ruled B-full semantic change: flip tagged-union variant matching
from surface-NAME to TYPE-identity (typeeq over tinfo.params), mirroring
cstage cg_variant_match (cmd/w6c/cgen.c:451). A cross-module `a.T` != `b.T`
and `type linerr=!str` != str are now distinguished by the per-decl TY_NAMED
pointer (Phase-N #64). ww has no type_assignable, so the untyped/loose arm
keeps the str/slice shape fallback (rule-10 align-down). The 5 helpers
(flatvariantidx, flatslicevariantidx, taggedvariantindex, cgtagvariantidx,
cgmatch dispatch) flip; nomem propagation (NAMED-name scan, no source value)
and the f64 widen arm (float-kind classification, no pattern node) are not
arm-by-value discrimination and stay name/kind-keyed.

The flip requires value nodes to carry nominal identity. exprtype's
N_STRUCTLIT arm stamped the flattened body, so `overflow{}` (overflow=!void)
got TY_VOID and missed its variant -- fixed to stamp the per-decl NAMED
(mktname(lhs.str) -> tinfofornode reuses the #64 NAMED build/cache, same ptr
the union variant resolved to), mirroring the N_CAST/N_IDENT arms + cstage.
Returns the body node unchanged (only e.type_ rides NAMED); struct-lit layout
is unaffected -- cgstructlitfill is structlookup(name)-keyed, never reads
NAMED.fields. The fix now hits all `T{}` stamps, kept byte-id by the #63/#65
structural-walker peels.

931_variant_typekey_run: table-driven, both stages, /tmp-isolated. Two rows
widen an alias-FIRST variant from a call (no surface name): `(linerr|str)`
str-via-call -> idx 1, `(ec|i32)` i32-via-call -> idx 1. Empirically
discriminating: FAILS pre-flip (wwstage falls to the leading-shape variant,
exit 10; cstage exit 0) and PASSES post-flip -- locking in the capability
byte-id can't reach (the corpus has no name-key/type-key-disagreeing
co-variant, which is why name-keying survived).

make test 134/134 (byte-id 990-997 green; 995 self-rebuild green).
This commit is contained in:
Hojun-Cho
2026-05-23 21:22:24 +09:00
parent 0fde4beeb4
commit 3036ba766d
8 changed files with 634 additions and 369 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
selfhost/cmd/wcc/check.ww
View File

@@ -2128,7 +2128,26 @@ fn exprtype(c: *checker, e: *node, hint: *node) *node = {
if (ms != nil) { if (ms.skind == skind.SK_TYPE) { if (ms.decl != nil) {
let tn: *node = ms.decl.lhs;
if (tn != nil) {
e.type_ = tinfofornode(c, tn): *void;
// #66 Phase-N step 3: stamp e.type_ to the NOMINAL
// per-decl NAMED, not the flattened body. `overflow{}`
// where `type overflow = !void` must carry
// NAMED(overflow) so the typeeq variant match
// (cgenutil flatvariantidx) selects the overflow arm
// instead of falling to the scalar shape fallback;
// stamping tinfofornode(tn) gave the body (TY_VOID)
// and lost nominal identity. Resolve through a
// synthesized TNAME to reuse tinfofornode's TY_NAMED
// build/cache (check.ww:1157) — the SAME NAMED ptr
// the union variant resolved to. Mirrors cstage
// resolving overflow{} to the overflow Type, and ww's
// own N_CAST / N_IDENT arms which already stamp NAMED.
// Return the body node tn unchanged: byte-id rides
// e.type_ (cgen), while the checker's AST-level
// assign/return checks keep their prior input.
let tnm: *node = mktname(c, e.lhs.str);
let nti: *tinfo = tinfofornode(c, tnm);
if (nti != nil) { e.type_ = nti: *void; }
else { e.type_ = tinfofornode(c, tn): *void; };
return tn;
};
}; }; };