Files
sx/examples/0166-types-union-promoted-member-lvalue.sx
agra d8076b9333 lang: rename signed integer types sN -> iN
Surface rename of the signed integer family: s1..s64 become i1..i64
(u1..u64, usize, isize unchanged). 'string' keeps the s-prefix arm in
name classification; width parsing moves to the i-prefix arm next to
isize.

Internal TypeId tags follow the surface (.s8/.s16/.s32/.s64 ->
.i8/.i16/.i32/.i64), as do mono-key mangle fragments (ptr_i64,
tu_i64_bool) and all display/diagnostic formatting (i{d}).

Migrated in the same sweep: stdlib + examples + issue repros + FFI C
companions (shared symbol names like ffi_id_i64), expected
stdout/stderr/ir snapshots, specs.md, readme.md, CLAUDE.md/AGENTS.md,
implementation_plan.md, docs/, issue writeups. Vendored stb_image and
historical flow state left untouched.

zig build test: 426/426; examples suite: 595/595.
2026-06-12 09:31:53 +03:00

33 lines
1.1 KiB
Plaintext

// Taking the address of a promoted anonymous-struct union member yields a
// pointer to that member's slot, so mutating through the pointer is visible
// through the member. The write path (`v.x = 41`) and the read path already
// resolve promoted members; the lvalue-pointer path (`@v.x`) now resolves them
// too, via the shared field-lvalue resolver.
//
// Regression (issue 0094, attempt 2): lowerExprAsPtr's union branch handled
// only DIRECT union field names, so `@v.x` on a promoted member reported
// "field 'x' not found on type 'Vec2'" even though `v.x = 41` worked. The
// over-rejection is gone, and a member that is NOT at offset 0 (`v.y`) resolves
// to its own slot — not a default field 0.
#import "modules/std.sx";
Vec2 :: union {
data: [2]i64;
struct { x: i64; y: i64; };
}
bump :: (p: *i64) {
p.* = p.* + 1;
}
main :: () {
v : Vec2 = ---;
v.x = 41;
v.y = 100;
bump(@v.x); // promoted member at offset 0 → 42
bump(@v.y); // promoted member at offset 8 → 101 (its own slot)
print("x={}\n", v.x);
print("y={}\n", v.y);
}