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).
A closure literal whose body raises but is annotated non-failable (or has
no ! in its return) now gets a lambda-specific diagnostic telling the user
to declare the failable return explicitly, instead of the generic "raise
is only valid inside a failable function". Failability is never inferred
for a lambda, so a raising lambda with no ! is a hard error that should
point at the fix.
New in_lambda_body flag (save/restore for nesting) set around the lambda
body lowering in lowerLambda; diagRaiseNotFailable branches on it.
Top-level functions keep the generic message.
Test: 1043-errors-lambda-raise-annotation-hint.sx.
