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wwstage: register error-structs in collectstructs so large-union struct-variant returns widen (#9)

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collectstructs registered a struct only when the typedecl body is N_TSTRUCT, so an error-struct (type X = !struct{...}, whose body is N_TBANG{N_TSTRUCT}) never entered wwstage's c.structs table. The name-keyed structlookup then missed at the return-widen sites, and wwstage dropped the struct construction when returning a struct variant of a large (>4-eightbyte) union -- wrong runtime value and cs!=ww. cstage has no struct name-table (pure tinfo) and was correct. Peel the N_TBANG body in collectstructs so error-structs register; both existing cstage-mirrored widen arms then fire. Provably byte-id-inert: no committed source defines a !struct today. Adds test/wcc/785 (struct-variant return + named-void control, both-stage byte-id + runtime). The >4-eightbyte 5th-word truncation on return remains, symmetric (cs==ww) and unread by the tag/early-word path; #222's sret hidden-pointer cutover is the committed fix (table-retirement tracked as the wwstage->tinfo SSoT arc). Aligns wwstage up to cstage (rule-10).
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Hojun-Cho
2026-05-30 04:54:12 +09:00
parent 7d39f6d623
commit 34c437fd63
6 changed files with 355 additions and 0 deletions
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Makefile
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@@ -336,6 +336,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_fieldfn_leaf_collide_run \
$(BIN)/test_amp_fn_assign_run \
$(BIN)/test_xmod_alias_struct_collide_run \
$(BIN)/test_structvariant_largeunion_return \
$(BIN)/test_bufio_vstream_run \
$(BIN)/test_log_vstream_run \
$(BIN)/test_use_promote_alias \
@@ -740,6 +741,16 @@ $(BIN)/test_xmod_alias_struct_collide_run: test/wcc/784_xmod_alias_struct_collid
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
# #9: returning a STRUCT variant of a LARGE (>4-eightbyte) tagged union.
# Both-stage byte-id + runtime (reads tag AND the widened &fn field, so a
# dropped-store regression can't hide behind self-consistent byte-id).
# Self-contained single-file probes via the driver, no lib imports.
$(BIN)/test_structvariant_largeunion_return: test/wcc/785_structvariant_largeunion_return.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_fmt_vstream_mods_run: test/wcc/780_fmt_vstream_mods_run.c \
$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \