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lang: introduce cstring — the C-boundary string (Odin model)

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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.
This commit is contained in:
agra
2026-06-12 14:50:53 +03:00
parent d88bdd7242
commit 1d17b0abcf
58 changed files with 26437 additions and 25257 deletions
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8
src/ir/conversions.zig
View File

@@ -43,11 +43,15 @@ pub const CoercionResolver = struct {
widen, // same kind, dst wider
narrow, // same kind, dst narrower
array_to_slice, // [N]T → []T (materialize backing storage + header)
string_to_cstring, // literal-only implicit; other strings need to_cstring
cstring_to_string_reject, // explicit from_cstring required (diagnostic)
none, // nothing applies — pass the value through
};
pub fn classify(self: CoercionResolver, src_ty: TypeId, dst_ty: TypeId) CoercionPlan {
if (src_ty == dst_ty) return .no_op;
if (src_ty == .string and dst_ty == .cstring) return .string_to_cstring;
if (src_ty == .cstring and dst_ty == .string) return .cstring_to_string_reject;
if (src_ty == .any and dst_ty != .any) return .unbox_any;
if (dst_ty == .any and src_ty != .any) return .box_any;
@@ -113,8 +117,8 @@ pub const CoercionResolver = struct {
const dst_float = Lowering.isFloat(dst_ty);
const src_int = self.l.isIntEx(src_ty);
const dst_int = self.l.isIntEx(dst_ty);
const src_ptr = !src_ty.isBuiltin() and self.l.module.types.get(src_ty) == .pointer;
const dst_ptr = !dst_ty.isBuiltin() and self.l.module.types.get(dst_ty) == .pointer;
const src_ptr = (!src_ty.isBuiltin() and self.l.module.types.get(src_ty) == .pointer) or src_ty == .cstring;
const dst_ptr = (!dst_ty.isBuiltin() and self.l.module.types.get(dst_ty) == .pointer) or dst_ty == .cstring;
if (src_int and dst_float) return .int_to_float;
if (src_float and dst_int) return .float_to_int;