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).
29 lines
1.0 KiB
Plaintext
29 lines
1.0 KiB
Plaintext
// Failable calls in cleanup bodies must be absorbed locally (ERR step E1.7). A
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// `defer` / `onfail` body runs while the block is already exiting, so a failable
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// it calls has nowhere to propagate — it must be handled in place with `catch`
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// or an `or <value>` terminator. This file shows the accepted forms; the bare
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// (un-absorbed) form is rejected in 1049.
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#import "modules/std.sx";
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E :: error { Bad }
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failing :: () -> !E { raise error.Bad; }
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recover :: () -> (i32, !E) { raise error.Bad; }
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work :: (n: i32) -> !E {
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defer print("defer: always\n"); // plain cleanup
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onfail { failing() catch (e) print("onfail: caught (catch)\n"); } // catch absorbs
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onfail { x := recover() or 7; print("onfail: x={} (or)\n", x); } // or-value absorbs
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if n < 0 { raise error.Bad; }
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return;
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}
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main :: () -> i32 {
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print("[error]\n");
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a := work(-1); // raises → onfail bodies fire, then defer (reverse decl order)
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print("[ok]\n");
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b := work(2); // success → only defer fires
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return 0;
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}
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