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).
30 lines
1.2 KiB
Plaintext
30 lines
1.2 KiB
Plaintext
// Failable `-> !` main entry-point wrapper (ERR step E4.2). A pure-failable
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// main that lets an error reach the function boundary exits 1 and prints the
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// unhandled-error header (with the tag name, via the always-linked tag-name
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// table) plus the return trace to stderr — instead of the old behavior of
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// returning the raw tag id as the exit code with no diagnostic. A successful
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// run (no escaping error) exits 0.
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//
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// Note: the header + trace go to stderr. The test runner merges stderr+stdout,
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// so the snapshot shows them interleaved with the `print` (stdout) lines.
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// Frame locations are placeholders until DWARF (ERR E3.0); count + ordering +
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// the tag name are already meaningful. Expected exit code: 1.
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#import "modules/std.sx";
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ParseErr :: error { Empty, BadDigit };
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inner :: (n: i32) -> (i32, !ParseErr) {
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if n == 0 { raise error.Empty; } // pushes a frame
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if n < 0 { raise error.BadDigit; }
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return n * 2;
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}
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main :: () -> !ParseErr {
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v := try inner(5); // succeeds → v = 10
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print("v = {}\n", v);
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w := try inner(0); // raises Empty → propagates to main
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print("w = {}\n", w); // never reached
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return;
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}
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