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).
44 lines
1.4 KiB
Plaintext
44 lines
1.4 KiB
Plaintext
// Value-carrying failable functions (`-> (T, !E)`) whose body ends in a trailing
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// success EXPRESSION (no explicit `return`) must set the success error slot to
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// 0 — the caller's `catch` must NOT fire and the success value must be intact.
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// Regression (issue 0190): `lowerValueBody` used to `coerceToType`+`ret` the
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// bare success value to the full failable tuple, leaving the error-tag slot
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// uninitialized → phantom catch on success (and dropped value for string /
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// multi-value returns).
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#import "modules/std.sx";
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E :: error { Bad }
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// Single-value trailing-expression success.
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val :: () -> (i64, !E) { 99 }
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// String trailing-expression success.
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sval :: () -> (string, !E) { "hi" }
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// Multi-value (tuple) trailing-expression success.
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mval :: () -> (i64, i64, !E) { .(1, 2) }
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// A real error still propagates through the value-failable channel.
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fval :: (n: i64) -> (i64, !E) {
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if n < 0 { raise error.Bad; }
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n + 1
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}
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main :: () -> i32 {
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x := val() catch (e) { print("PHANTOM val\n"); return 1; };
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print("x={}\n", x);
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s := sval() catch (e) { print("PHANTOM sval\n"); return 1; };
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print("s={}\n", s);
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t := mval() catch (e) { print("PHANTOM mval\n"); return 1; };
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print("t=({},{})\n", t.0, t.1);
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ok := fval(10) catch (e) { print("PHANTOM fval-ok\n"); return 1; };
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print("ok={}\n", ok);
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fval(-1) catch (e) { print("real error caught\n"); return 0; };
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print("UNEXPECTED no error\n");
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return 1;
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}
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