83ec2536af
try foo() catch (e) { } // legal
try foo() catch e { } // parse error with a migration hint
Same capture style as the for-loop. All four catch shapes keep working
with the parenthesized binding — block, bare-expression body, and the
== match sugar — and the no-binding forms are unchanged. onfail follows
the same rule (onfail (e) { }); its expression-cleanup form is
disambiguated by the paren-group-before-brace lookahead, so
onfail (f()); stays an expression cleanup.
AST unchanged; the printer renders the parens; the #run escape help
text updated. Corpus migrated (57 catch + 3 onfail bindings, in-source
parser test strings, specs incl. grammar rules, readme untouched —
no catch examples there).
Regression: examples/1157-diagnostics-catch-binding-needs-parens.sx;
re-captured stderr for 1010/1013/1037/1123 (migrated source echoed in
carets + help text).
43 lines
1.4 KiB
Plaintext
43 lines
1.4 KiB
Plaintext
// `onfail` — cleanup that runs only when an error LEAVES the enclosing block
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// (ERR step E1.7). Unlike `defer` (which runs on every exit), `onfail` fires
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// on an error exit — a `raise` or a propagating `try` — and is skipped on
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// success. On an error exit `defer` and `onfail` run interleaved in reverse
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// declaration order. `onfail (e) { … }` binds the in-flight error tag.
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// (Per-attempt-`try` gating and `or`-chain absorption refine this in E2.4b.)
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#import "modules/std.sx";
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E :: error { Bad }
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inner :: (n: s32) -> !E {
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if n < 0 { raise error.Bad; }
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return;
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}
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// defer + onfail interleave on the error path; only defers on success.
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run :: (n: s32) -> !E {
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defer print("defer A\n");
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onfail print("onfail B\n");
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defer print("defer C\n");
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try inner(n); // n<0 → propagates → onfail fires
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return;
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}
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// `onfail e` binds the tag.
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classify :: (n: s32) -> !E {
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onfail (e) { if e == error.Bad { print("cleanup: bad\n"); } }
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if n < 0 { raise error.Bad; }
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return;
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}
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main :: () -> s32 {
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print("[fail]\n");
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a := run(-1); // error → defer C, onfail B, defer A
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print("[ok]\n");
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b := run(7); // success → defer C, defer A (no onfail)
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print("[bound]\n");
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c := classify(-1); // onfail binding sees Bad
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print("[done]\n");
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return 0;
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}
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