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).
35 lines
1.5 KiB
Plaintext
35 lines
1.5 KiB
Plaintext
// Dead statements after a block-terminating statement (`return` / `raise`) are
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// dropped instead of being emitted into the already-closed basic block.
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// Regression (issue 0061): a bare `return X;` / `raise` mid-block closed the
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// LLVM basic block but lowering kept emitting the trailing statements into it
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// → "Terminator found in the middle of a basic block". The canonical failable
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// closure form `{ raise error.X; return x; }` tripped this, blocking ERR E5.1.
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//
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// The fix must NOT over-reach: a CONDITIONAL `if cond { return }` (and the
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// `inline if` pack form) leaves a fresh merge block, so its trailing statements
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// must still run — exercised by `clamp` / `pick` below.
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#import "modules/std.sx";
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E :: error { Neg }
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// dead `return 99;` after an unconditional return
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const_one :: () -> i64 { return 1; return 99; }
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// dead `return x;` after an unconditional raise (the failable closure shape)
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always_raise :: (x: i64) -> (i64, !E) { raise error.Neg; return x; }
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// guard: a conditional return must still fall through to the trailing return
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clamp :: (x: i64) -> i64 { if x > 10 { return 10; } return x; }
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main :: () -> i32 {
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print("const_one={}\n", const_one()); // 1
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print("raised={}\n", always_raise(5) catch (e) 0); // 0
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print("clamp_hi={}\n", clamp(42)); // 10
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print("clamp_lo={}\n", clamp(7)); // 7
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// dead code after a `return` at main's own block level is dropped.
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return 0;
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print("unreachable\n")
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}
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