Files
sx/examples/1051-errors-cleanup-closure-boundary.sx
agra 83ec2536af lang: catch/onfail error bindings take parens
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).
2026-06-10 23:05:02 +03:00

49 lines
1.8 KiB
Plaintext

// A closure literal inside a `defer` / `onfail` body is its OWN function
// boundary (ERR step E1.7). Two boundary effects, both pinned here:
//
// (a) `checkCleanupNode` sees a bare lambda STATEMENT as a `.lambda` node and
// STOPS — it does not descend into the lambda body. So the bare failable
// inside the lambda is the lambda's concern, not a cleanup violation
// (were the `.lambda` arm to recurse, this bare `failing()` would reject
// like the ones in 1052).
//
// (b) value-slot liveness (E1.8) is analysed per-boundary: `flowExpr` recurses
// into the lambda via `analyzeFnBody`, so a value slot read inside the
// lambda must prove its own error absent — `v` here is live under its
// `if !err` guard. (The rejecting counterpart is 1053.)
//
// Also: `try` is legal inside the lambda (it propagates through the lambda's own
// `!E` channel) even though it is parser-banned in the cleanup body directly.
//
// Locks the closure-boundary arms of the error-flow pass before A5.2 extracts it
// into its own module. Constructible since issue 0073 (closure literal in a
// `defer` body no longer segfaults lowering — see 0310).
#import "modules/std.sx";
E :: error { Bad }
failing :: () -> !E { raise error.Bad; }
recover :: () -> (s32, !E) { return 21; }
work :: () {
defer {
// (a) bare lambda statement — checkCleanupNode stops at the `.lambda`.
() -> !E { failing(); };
// (b) called closure — its body is analysed as its own boundary.
emit := () -> !E {
v, err := recover();
if !err { print("defer closure: v={}\n", v); } // E1.8: live under guard
try failing();
};
emit() catch (e) print("defer closure: raised\n");
}
print("body\n");
}
main :: () -> s32 {
work();
return 0;
}