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selfhost/cmd/wcc/cgenutil+test: slotsize zero for void, recurse N_TBANG

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Wwstage's slotsize had a catch-all `return 8` for any N_TNAME where
primsize's `> 0` guard failed. `primsize("void") == 0` (correct —
void is zero-sized per cmd/wcc/type.c:46), so void landed on the
catch-all. (void | !void) then sized as `8 (tag) + max(8, 8) = 16`
instead of `8 + 0 = 8`, and the phantom payload word made
cgwidentaggedstore spill DX for the let-init — diverging from
cstage's `8`-byte slot.

Two narrow additions per rule 10 (align wwstage DOWN to cstage):
1. N_TBANG case at the top of slotsize, recurse on .lhs. Mirrors
   cstage resolve_type N_TBANG which copies the underlying type's
   size unchanged.
2. `void => 0` in N_TNAME BEFORE the primsize guard, so the SSoT
   matches cmd/wcc/type.c:46.

757_letbind_void_bang_void exercises three shapes — void-arm,
invalid-arm, full natural-form fromutf8 — and pins cstage/wwstage
asm byte-identity per row.

lib/strings/strings.ww fromutf8 WHY-comment drops the Bug-B
SIGSEGV caveat (measurement artifact: original test linked without
rt/start.s; RET popped argc). Keeps #19 dependency for the
eventual collapse to `utf8.validate(in)?`.

Hare matches ww's design (void zero-sized, !T inherits T's
layout); this is a pure wwstage implementation gap, not a
divergence to argue about.
This commit is contained in:
Hojun-Cho
2026-05-20 02:27:17 +09:00
parent 6d006da26c
commit f8770d1502
7 changed files with 334 additions and 40 deletions
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7
Makefile
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@@ -291,6 +291,7 @@ TESTS = $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
$(BIN)/test_slice_of_slice_index \
$(BIN)/test_amp_dot_idx \
$(BIN)/test_alias_chain_unwrap \
$(BIN)/test_letbind_void_bang_void \
$(BIN)/test_param_shadow_mod \
$(BIN)/test_localoff_scope \
$(BIN)/test_cast_enum_movl \
@@ -762,6 +763,12 @@ $(BIN)/test_alias_chain_unwrap: test/wcc/756_alias_chain_unwrap.c \
$(LIB)/libwwrt.a | $(BIN)
$(CC) $(CFLAGS) -o $@ $<
$(BIN)/test_letbind_void_bang_void: test/wcc/757_letbind_void_bang_void.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_match_4arm_cross_module_run: test/wcc/929_match_4arm_cross_module_run.c \
$(BIN)/ww $(BIN)/w6c $(BIN)/w6a $(BIN)/w6l \
$(BIN)/ww_ww $(BIN)/w6c_ww $(BIN)/w6a_ww $(BIN)/w6l_ww \