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Propagate all closure requirements to the caller #56486

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2 changes: 1 addition & 1 deletion src/librustc_mir/borrow_check/nll/region_infer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1208,7 +1208,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
blame_span: blame_span_category.1,
category: blame_span_category.0,
});
return;
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continue;
}
}

Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
// Test that we propagate *all* requirements to the caller, not just the first
// one.

#![feature(nll)]

fn once<S, T, U, F: FnOnce(S, T) -> U>(f: F, s: S, t: T) -> U {
f(s, t)
}

pub fn dangle() -> &'static [i32] {
let other_local_arr = [0, 2, 4];
let local_arr = other_local_arr;
let mut out: &mut &'static [i32] = &mut (&[1] as _);
once(|mut z: &[i32], mut out_val: &mut &[i32]| {
// We unfortunately point to the first use in the closure in the error
// message
z = &local_arr; //~ ERROR
*out_val = &local_arr;
}, &[] as &[_], &mut *out);
*out
}

fn main() {
println!("{:?}", dangle());
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
error[E0597]: `local_arr` does not live long enough
--> $DIR/propagate-multiple-requirements.rs:17:14
|
LL | let mut out: &mut &'static [i32] = &mut (&[1] as _);
| ------------------- type annotation requires that `local_arr` is borrowed for `'static`
LL | once(|mut z: &[i32], mut out_val: &mut &[i32]| {
| ----------------------------------------- value captured here
...
LL | z = &local_arr; //~ ERROR
| ^^^^^^^^^ borrowed value does not live long enough
...
LL | }
| - `local_arr` dropped here while still borrowed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0597`.