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lang: catch/onfail error bindings take parens

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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).
This commit is contained in:
agra
2026-06-10 23:05:02 +03:00
parent 12149eb548
commit 83ec2536af
42 changed files with 158 additions and 115 deletions
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6
examples/1040-errors-failable-closure-composition.sx
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@@ -12,7 +12,7 @@
E :: error { Neg }
bare :: (cb: (s64) -> (s64, !E), n: s64) -> s64 { return cb(n) catch e -1; }
bare :: (cb: (s64) -> (s64, !E), n: s64) -> s64 { return cb(n) catch (e) -1; }
chain :: (cb: Closure(s64) -> (s64, !E), n: s64) -> (s64, !E) { return try cb(n); }
dbl :: (x: s64) -> (s64, !E) { if x < 0 { raise error.Neg; } return x * 2; }
@@ -25,8 +25,8 @@ main :: () -> s32 {
// Closure(...) param, try-propagated, then caught at the call site
print("chain ok={} err={}\n",
chain(closure((x: s64) -> (s64, !E) => x + 6), 4) catch e 0, // 10
chain(closure((x: s64) -> (s64, !E) { raise error.Neg; }), 1) catch e 0); // 0
chain(closure((x: s64) -> (s64, !E) => x + 6), 4) catch (e) 0, // 10
chain(closure((x: s64) -> (s64, !E) { raise error.Neg; }), 1) catch (e) 0); // 0
// NON-failable closure literal widened into the failable bare slot
print("widen={}\n", bare(closure((x: s64) -> s64 => x + 1), 9)); // 10