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.
cstring is ONE pointer to a null-terminated u8 buffer, C's char*: thin
(8 bytes, no length; cstring_len walks to the terminator), crossing
#foreign boundaries verbatim in both directions, with ?cstring as the
nullable case lowering to the same bare pointer (null = absent).
Conversion discipline mirrors Odin: a string LITERAL coerces implicitly
(its bytes are terminated constants); any other string is rejected with
a diagnostic naming to_cstring (it may be an unterminated view); and
cstring never coerces to string implicitly — from_cstring(c) is the
explicit zero-copy view, pricing the strlen.
Plumbing: TypeId/TypeInfo builtin slot 18 (first_user 19), name
classifiers, size/align/name tables, LLVM ptr lowering, the ?T pointer
niche, the xx pointer ladder, the literal-gated coercion plan
(isConstString + data_ptr), and the reserved-spelling set. std gains
cstring_len/from_cstring/to_cstring (fmt.sx, re-exported); the old
cstring(size) allocator helper is renamed alloc_string everywhere;
getenv migrates to (name: cstring) -> ?cstring as the canonical user
and env() drops its manual strlen/memcpy.
Pinned: examples/1222 (FFI both directions, literal coercion,
?cstring null paths, round trip) and examples/1173 (both coercion
diagnostics); FAIL pre-feature. The alloc_string rename + getenv
signature shift the .ir snapshots — regenerated. zig build test
426/426; run_examples 604/604.
Spec: reserved spelling + cstring section + C-interop rows.
