12 plain-C examples that use #foreign incidentally (as FFI plumbing, output
unchanged): 1200/1206/1209-1215/1220/1221/1222. Blanket keyword swap; all fn/global
markers (no class forms in 12xx). Empty snapshot diff; corpus validates directly
(all marker'd). Suite green (647 corpus / 444 unit, 0 failed).
KEPT on #foreign (deferred to Phase 8 cutover): identity-#foreign feature tests
(filename ffi-foreign-*: 1205/1207/1216/1218/1219), the equivalence test 1228, and
the diagnostics that assert on #foreign source/message (1172/1174/1620). Comment-only
provenance prose (1223/1229/1230/1231) left intact per Decision-6-recommended.
Two genuine defects behind the 0128 filing (whose original repros were
both poisoned by binding getenv, which std already declares -> *u8):
1. Re-declaring a C symbol was silent first-wins: every call through
the later declaration was typed by the older signature. Foreign
registration now dedupes — equal signatures share one FuncId,
conflicting ones are diagnosed.
2. Foreign -> string / -> ?string returns read garbage: C returns one
char*, but the LLVM signature declared the fat {ptr,i64} (len =
register garbage), and ?string was mis-declared SRET (the hidden
out-pointer landed in the callee's first arg register). cstrRetKind
now classifies such returns, declares them as plain ptr (never
sret), and the call site synthesizes {ptr, strlen} via a
branch-guarded strlen (NULL -> {null,0} / optional null), wrapping
{string, i1} for ?string.
?[:0]u8 itself resolves fine (it is ?string); the spelling works in
return, param, local, and alias positions.
Regression: examples/1221 (plain + optional non-null + NULL paths) and
examples/1172 (conflict diagnostic); both FAIL pre-fix. The extern
dedupe collapses duplicate libc decls, so affected .ir snapshots were
regenerated. zig build test 426/426; run_examples 602/602;
distribution suite 21/21.
