213cedf0b5
The trailing-`!`-after-the-value-type spelling (`-> T !`, `-> Tuple(A,B) !`) was a
redundant second way to write a failable return that the parser folded into the
same AST as the parenthesized `(T, !)` / `(A, B, !)` result list. Remove it so
there is ONE canonical spelling: the error channel always rides as the last slot
of the parenthesized list.
- parser: `parseFnReturnType` no longer folds a trailing `!` after a value type —
it rejects it with a located diagnostic ("a failable return is written `(T, !)`
… not `T !`"). This one chokepoint covers fn declarations, lambdas, fn-pointer
types `(A) -> R`, and closure types `Closure(A) -> R`. The error-ONLY `-> !` /
`-> !ErrSet` form is unaffected (parsed by parseTypeExpr as an error_type_expr).
- migrated every usage to canonical form across library/ + examples/ + issues/ +
tests/: `-> T !E` → `-> (T, !E)`; the value-carrying `-> Tuple(A, B) !` (which
FLATTENED to a multi-value failable) → `-> (A, B, !)`, preserving behavior. A
genuine single-tuple-value failable stays `-> (Tuple(A,B), !)`.
- parser unit tests: the "bare form folds" tests become "bare form is rejected";
canonical-form parse tests retained.
- docs: specs.md §12 + scattered refs and readme.md updated to the `(T, !)` form.
Behavior-preserving (the bare form was sugar for the same AST). Adversarial review
confirmed: rejection complete across all positions, every canonical form works on
both success/error paths, error-only `-> !` intact, no crashes. Full suite green
(unit tests + 850 corpus examples).
27 lines
912 B
Plaintext
27 lines
912 B
Plaintext
// A failable function returning a NAMED tuple value `-> (x: A, y: B, !E)`
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// flattens its value fields into the result tuple (`{ x: A, y: B, err }`),
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// keeping the `.x`/`.y` names addressable on both the success value and the
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// `or` fallback. Exercises the success path, a `raise` path, and an
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// `or .(x=.., y=..)` terminator.
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//
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// Regression (issue 0179-adjacent named-tuple-failable miscompile): a named
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// failable tuple used to WRAP as `{ {A,B}, err }` while the value-return
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// lowering inserted the value slots FLAT, producing invalid LLVM
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// (`Invalid InsertValueInst operands`).
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#import "modules/std.sx";
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E :: error { Bad }
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two :: (n: i64) -> (x: i64, y: i64, !E) {
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if n < 0 { raise error.Bad; }
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return .(x = n, y = n + 1);
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}
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main :: () {
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ok := two(5) or .(x = 0, y = 0);
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print("{} {}\n", ok.x, ok.y);
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bad := two(-1) or .(x = 0, y = 0);
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print("{} {}\n", bad.x, bad.y);
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}
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