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).
45 lines
2.1 KiB
Plaintext
45 lines
2.1 KiB
Plaintext
// Enum-valued value-carrying failable: the SUCCESS path must zero the trailing
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// error slot. Regression (issue 0097). A `-> (Enum, !E)` `return .variant`
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// resolves the enum literal against the function's VALUE type (the enum), not
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// the failable tuple — otherwise the literal mis-resolves (tag 0) and is stamped
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// with the tuple type, which the success-return lowering mistakes for a forwarded
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// full tuple and leaves the error slot UNDEFINED (read back as garbage nonzero).
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//
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// This pins the slot at RUNTIME on the success path (cast(i64) e, bare `if e`,
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// and `e == error.X`) — not only via the `if !e` proof that the compiler can
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// fold away. It also exercises a non-zero ordinal (`.blue` = 2) so a value slot
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// that collapses to 0 is caught, and asserts the error PATH still carries the
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// right tag and `error_tag_name`.
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#import "modules/std.sx";
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Color :: enum { red; green; blue; }
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E :: error { Nope }
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pick :: (s: string) -> (Color, !E) {
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if s == "red" { return .red; }
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if s == "blue" { return .blue; } // non-zero ordinal (2)
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raise error.Nope;
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}
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main :: () -> i32 {
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// ── success path: error slot MUST read 0 at runtime ──
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c, e := pick("red");
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print("success err int = {}\n", cast(i64) e); // 0
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if e { print("bare-if e: ERROR (WRONG)\n"); } else { print("bare-if e: ok\n"); }
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if e == error.Nope { print("e == Nope (WRONG)\n"); } else { print("e != Nope (ok)\n"); }
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if !e { print("guard !e: c = {}\n", cast(i64) c); } // 0 (red)
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// ── non-zero ordinal: value slot must carry the real ordinal ──
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c2, e2 := pick("blue");
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if !e2 { print("blue: err int = {}, c = {}\n", cast(i64) e2, cast(i64) c2); } // 0, 2
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// ── error path: the right tag flows through ──
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c3, e3 := pick("xxx");
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print("error err nonzero = {}\n", cast(i64) e3 != 0); // true (ordinal is program-global, not pinned)
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if e3 == error.Nope { print("error: is Nope (ok)\n"); } else { print("error: not Nope (WRONG)\n"); }
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print("error tag name = {}\n", error_tag_name(e3)); // Nope
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return 0;
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}
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