// `??` (null-coalesce) requires an optional left operand. A resolved
// non-optional lhs is malformed user input and must be a clean, located type
// error — not a compiler crash. Regression (issue 0172): `lowerNullCoalesce`
// used to feed the `.unresolved` inner type (from `resolveOptionalInner` on a
// non-optional lhs) straight into the merge-block params / `optionalUnwrap` /
// the RHS target type, which reached emit_llvm's "unresolved type reached LLVM
// emission" panic (exit 134) with no diagnostic. A guard now inspects the
// inferred lhs type: a resolved non-optional emits this error and bails before
// codegen; an already-`.unresolved` lhs (a prior error, e.g. undefined name)
// passes through untouched so the original diagnostic isn't double-reported.

#import "modules/std.sx";

main :: () {
  x := 5 ?? 7;   // <- left operand of '??' must be an optional, but has type 'i64'
  print("{}\n", x);
}