Files
sx/examples/closures/0314-closures-capture-failable-call.sx
agra 69a6ecfb57 fix: capture failable closures called via error-handling exprs
collectCaptures did not descend into catch/try/onfail/raise/multi_assign/
push/comptime/insert/spread/asm nodes, so a free variable referenced only
inside them (e.g. a failable worker called as `worker() catch {…}` in a
nested lambda) was never captured into the env struct — inside the lambda
it resolved against an empty scope and typed as 'unresolved'. Add the
missing traversal arms. The push_stmt arm also closes the noted
'free-var analysis does not descend into a nested push Context {…}' gap.

Unblocks the PLAN-IO-UNIFY Phase 3 async completion closure shape.
Lock: examples/closures/0314-closures-capture-failable-call.sx.
2026-06-28 09:18:15 +03:00

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// A captured FAILABLE closure stays failable when CALLED inside a nested
// closure body. The free-variable capture analysis must descend into the
// error-handling expressions (`catch`, `try`) that the nested closure uses to
// consume the captured worker's error channel — otherwise the worker is never
// captured into the env, resolves against an empty scope inside the lambda, and
// the call types as `unresolved` (so `catch`/`try` reject it).
//
// Regression (PLAN-IO-UNIFY Phase 3 blocker): the async completion closure
// `() => { f.value = worker() catch {…} }` captures a `Closure() -> ($R, !)`
// worker and consumes its error channel — exactly this shape.
#import "modules/std.sx";
Box :: struct { run: Closure() -> void; }
// `catch` path: the nested closure absorbs the worker's error.
run_catch :: (worker: Closure() -> (i64, !)) {
b : Box = ---;
b.run = () => {
v := worker() catch {
print("caught\n");
return;
};
print("ok {}\n", v);
};
b.run();
}
// `try` path: the nested closure is itself failable and propagates.
mk_trier :: (worker: Closure() -> (i64, !)) -> Closure() -> (i64, !) {
return () -> (i64, !) => {
v := try worker();
v + 100
};
}
main :: () -> i64 {
run_catch(() -> (i64, !) => { 7 }); // ok 7
run_catch(() -> (i64, !) => { raise error.Bad; }); // caught
t := mk_trier(() -> (i64, !) => { 5 });
r := t() catch { return 1; };
print("try {}\n", r); // try 105
return 0;
}