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).
61 lines
2.1 KiB
Plaintext
61 lines
2.1 KiB
Plaintext
// Path-sensitive value-slot liveness (ERR step E1.8). After `v, err := f()`, the
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// value slot `v` is "live only where `err` is proven absent". Every read of `v`
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// below sits on a path where the compiler can prove `err == null`:
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//
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// • `if !err { … v … }` — proven inside the guard
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// • `if err { return } … v …` — proven on the fall-through
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// • `if err { raise } … v …` — fall-through in a failable function
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// • `if err { … } else { … v … }` — proven in the else branch
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// • `!err and <reads v>` — short-circuit keeps the proof
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//
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// A bare tag-compare (`if err == error.X`) proves NOTHING about absence — see the
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// rejection regression in 1047. (Regression for the E1.8 path-sensitive slice.)
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#import "modules/std.sx";
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E :: error { Bad, Empty }
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parse :: (n: s32) -> (s32, !E) {
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if n < 0 { raise error.Bad; }
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if n == 0 { raise error.Empty; }
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return n * 10;
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}
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// Early-return guard: the fall-through proves `err` absent.
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guarded :: (n: s32) -> s32 {
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v, err := parse(n);
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if err { return -1; }
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return v; // err proven absent here
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}
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// `if err { raise }` in a failable function: same fall-through proof.
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relay :: (n: s32) -> (s32, !E) {
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v, err := parse(n);
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if err { raise err; }
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return v + 1; // err proven absent here
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}
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main :: () -> s32 {
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total : s32 = 0;
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// (1) proven inside `if !err`
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v1, e1 := parse(5);
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if !e1 { total = total + v1; } // +50
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// (2) proven in the else branch
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v2, e2 := parse(7);
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if e2 { total = total + 1; } else { total = total + v2; } // +70
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// (3) short-circuit `&&` keeps the proof for the rhs
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v3, e3 := parse(3);
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if !e3 and v3 > 0 { total = total + v3; } // +30
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// (4) early-return / raise helpers
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total = total + guarded(4); // +40
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total = total + guarded(-1); // -1
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total = total + (relay(2) catch (e) 0); // parse(2)=20 → +1 = 21
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print("liveness total: {}\n", total); // 50+70+30+40-1+21 = 210
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return total;
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}
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