Files
sx/examples/diagnostics/1205-diagnostics-annotated-init-type-mismatch.sx
agra b322dcfe61 fix: type-safe stores + Any unbox/eq; finish multi-return deferrals
Type-checking gaps (segfault/corruption → compile errors):

- 0197: reject a store into an annotated slot whose value has no modeled
  coercion AND a different byte width (a 16-byte string into a 4-byte i32
  overran the slot and segfaulted). New checkAssignable / noneReinterpretIsUnsafe
  (coerce.zig, width via the LLVM-accurate typeSizeBytes) wired into every store
  site: var/const-decl, single + multi assignment (identifier/field/index/
  element/deref), named-return defaults. Same-width reinterpretations (*T→[*]T,
  i64→isize, fn-ref) and explicit xx/cast stay allowed; cascades suppressed via
  externalErrorsExist. Examples 1205, 1206.
- 0198: an implicit `Any → T` unbox is now a compile error (it blindly
  reinterpreted the boxed payload — silent garbage for a wrong scalar, a segfault
  for an aggregate). xx and compiler-generated match/pack unboxes are unaffected.
  Example 1207.
- 0199: `Any == <concrete>` (one operand Any) aborted the LLVM verifier — the
  comparison arm now fires when either operand is Any, boxing the concrete side
  first. Example 0654.

Multi-return deferrals (PLAN-MULTIRET #6 + named-order + D3 + generic):

- Reorder named return elements by name instead of requiring slot order; error on
  unknown/duplicate/missing (value-only AND full-failable-tuple forms). Examples
  0210, 0214.
- Reject a bare-paren (A, B) multi-return signature in generic-arg position
  (return-position-only). Example 0215.
- Multi-return closure types / lambda literals work via the reused tuple
  machinery (destructure, single-bind+field, lambda arg). Example 0216.
- Generic multi-return: positional works (0217); 0200: the named-slot
  implicit-return form now works for generic free fns + struct methods —
  monomorphizeFunction now calls bindNamedReturnSlots. Example 0218.

readme.md documents the annotated-store coercion rule; CHECKPOINT-MULTIRET.md
updated. Full corpus green (850/0).
2026-06-27 17:28:27 +03:00

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// Initializing (or reassigning) an explicitly-annotated slot with a value
// whose type has NO coercion to the annotation is a type error, diagnosed at
// lowering with a located message.
//
// Regression (issue 0197): `x : i32 = "hi"` was accepted with no diagnostic —
// the incompatible value passed through a `.none` coercion plan UNCHANGED, so a
// 16-byte `string` was stored into a 4-byte `i32` slot, bit-mangling the slot
// and SIGSEGV'ing at run time (`sx ir` lowered fine; only the run crashed). The
// guard (`checkAssignable`) now rejects an un-coercible initializer at every
// store-into-annotated-slot site — var-decl, body-local const-decl, and
// reassignment — emitting a diagnostic and aborting the build cleanly (exit 1).
//
// The explicit `xx` / `cast(T)` escape hatch is unaffected: a deliberate
// reinterpretation (pointer↔int, etc.) still passes through.
#import "modules/std.sx";
main :: () -> i64 {
x : i32 = "hi"; // error: cannot initialize 'x' (string ↛ i32)
y : i32 = 0;
y = "nope"; // error: cannot reassign 'y' (string ↛ i32)
C : i32 : "also"; // error: cannot initialize 'C' (string ↛ i32)
return 0;
}