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wcc: accept NAMED-variant nominal match at tagged→tagged subset (#205)

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The tagged→tagged subset arm walked src's leaves against dst's flat
variant list, so `let r: (size | eof | wrapper) = e` with e: wrapper
REJECTED at cstage's checker — wrapper's leaves (unsupported, underread,
nomem) aren't direct variants of dst. Wwstage's permissive tail
accepted silently but cgen then miscompiled the tag (#199b layout-
extension family, deferred).

Mirror the concrete→tagged fix from #199 (α) at type.c:316: when src is
a NAMED-tagged wrapper and dst has a direct NAMED-tagged variant equal
to src, accept by nominal identity BEFORE the subset loop. Wwstage's
isassignable mirrors the structural insertion before the existing
`*confident = false; return true;` tail (deferred-tightening per #202).
SSoT with `is`/`as` non-recursive variant lookup (#198 family).

Cgen's tag-remap for the wrapper-as-whole case still maps src variants
to dst tag 0 — the wrapped-slot layout for `dst.tag = variant_idx,
dst.payload = src` is #199b future-work. Probe verifies checker-accept
+ runtime exit-clean only; does NOT inspect the resulting variant tag.

Probe 774_tagged_widen_named_variant.c covers 5 rows: bug-repro,
nested-wrapper, pure-leaf subset (regression), concrete-unrelated
rejection (gate), branched callee. Two sibling cgen/checker bugs
surfaced (wwstage cgwidentaggedstorebp ssz<slot_sz pad gap; wwstage
isassignable !void-alias collapse) and documented inline at the
probe-row comment, kept in #202 family.
This commit is contained in:
Hojun-Cho
2026-05-29 06:18:27 +09:00
parent 3f4eeff7ff
commit 487cf91f12
6 changed files with 404 additions and 0 deletions
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7
Makefile
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@@ -324,6 +324,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_widen_transitive \
$(BIN)/test_typeassert_nonident \
$(BIN)/test_isas_spread_variant \
$(BIN)/test_tagged_widen_named_variant \
$(BIN)/test_use_promote_alias \
$(BIN)/test_field_signed $(BIN)/test_frame_argcount \
$(BIN)/test_selfhost $(BIN)/test_w6a_ww $(BIN)/test_w6l_ww \
@@ -674,6 +675,12 @@ $(BIN)/test_isas_spread_variant: test/wcc/773_isas_spread_variant.c \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_tagged_widen_named_variant: test/wcc/774_tagged_widen_named_variant.c \
$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_arrlit_str_full: test/wcc/711_arrlit_str_full.c \
$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \