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Propagate all closure requirements to the caller #56486

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Dec 4, 2018
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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;
}
}

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6 changes: 3 additions & 3 deletions src/librustc_typeck/check/wfcheck.rs
Original file line number Diff line number Diff line change
Expand Up @@ -355,13 +355,13 @@ fn check_item_type<'a, 'tcx>(
) {
debug!("check_item_type: {:?}", item_id);

for_id(tcx, item_id, ty_span).with_fcx(|fcx, _this| {
let ty = fcx.tcx.type_of(fcx.tcx.hir.local_def_id(item_id));
for_id(tcx, item_id, ty_span).with_fcx(|fcx, gcx| {
let ty = gcx.type_of(gcx.hir.local_def_id(item_id));
let item_ty = fcx.normalize_associated_types_in(ty_span, &ty);

let mut forbid_unsized = true;
if allow_foreign_ty {
if let TyKind::Foreign(_) = tcx.struct_tail(item_ty).sty {
if let TyKind::Foreign(_) = fcx.tcx.struct_tail(item_ty).sty {
forbid_unsized = false;
}
}
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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`.