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wcc/cgen: #52 error-first tagged-union success tag — successtag helper not hardcoded 0 (wwstage)

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An error-first tagged union -- error variant at tag 0, success at tag 1+,
e.g. (myerr | u16) -- was silently miscompiled by wwstage: the try/propagate
codegen hardcoded success = tag 0, so the actual success value (tag 1)
failed the CMPQ $0 and fell to the error path -> exit(1) instead of the
value (44). cstage was correct (computes the success tag via
cg_tagged_success_tag = first non-error variant).

wwstage-only: a successtag/successvariant helper (mirroring cstage) replaces
the hardcoded tag-0 / first-param assumption at all four try sites --
cgtryprop (?), cgtryunw (!), and the two latent shift sites cgtrytupleshift
+ cgtrytaggedshift (which bite an error-first union with an aggregate
success payload). Success-first unions (the Hare idiom + what the selfhost
uses) keep successtag=0 -> CMPQ $0 unchanged -> byte-id-neutral on 990-997.
cstage untouched (w6c md5 unchanged).

byte-id 990-997 8/8. test/wcc/825 table-driven (errfirst must/prop +
tuple-success + success-first control). A separate nested-tagged-union
construction divergence is filed (#10/#125).
This commit is contained in:
Hojun-Cho
2026-06-08 22:15:19 +09:00
parent ef6fcbfc04
commit fca979470f
5 changed files with 502 additions and 45 deletions
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7
Makefile
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@@ -253,6 +253,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_struct_global_byval_arg \
$(BIN)/test_inferred_global_let \
$(BIN)/test_inferred_float_global \
$(BIN)/test_errfirst_union_try \
$(BIN)/test_slice_str_global_zero \
$(BIN)/test_slice_literal_global \
$(BIN)/test_global_arr_elem_field \
@@ -679,6 +680,12 @@ $(BIN)/test_inferred_float_global: test/wcc/824_inferred_float_global.c $(BIN)/w
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_errfirst_union_try: test/wcc/825_errfirst_union_try.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_def_arr_infer_len: test/wcc/814_def_arr_infer_len.c $(BIN)/ww \
$(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \