Auto merge of #52106 - PramodBisht:issue/52049, r=oli-obk

Don't suggest `let` bindings if they don't help with borrows

@oli-obk I have added a condition to address #52049, right now, this is on WIP because I think code change is also required on `error_reporting.rs`. Plus I need to check if any test cases fail.
I will ping you again if everything passes

r? @oli-obk
This commit is contained in:
bors 2018-07-08 14:08:36 +00:00
commit 0e6b713dd5
4 changed files with 48 additions and 1 deletions

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@ -1011,8 +1011,11 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
let node_id = scope.node_id(self.tcx, &self.region_scope_tree);
match self.tcx.hir.find(node_id) {
Some(hir_map::NodeStmt(_)) => {
if *sub_scope != ty::ReStatic {
db.note("consider using a `let` binding to increase its lifetime");
}
}
_ => {}
}
}

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@ -0,0 +1,13 @@
error[E0597]: borrowed value does not live long enough
--> $DIR/issue-52049.rs:16:10
|
LL | foo(&unpromotable(5u32));
| ^^^^^^^^^^^^^^^^^^ temporary value does not live long enough
LL | }
| - temporary value only lives until here
|
= note: borrowed value must be valid for the static lifetime...
error: aborting due to previous error
For more information about this error, try `rustc --explain E0597`.

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@ -0,0 +1,18 @@
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
fn foo(_: &'static u32) {}
fn unpromotable<T>(t: T) -> T { t }
fn main() {
foo(&unpromotable(5u32));
}
//~^^ ERROR borrowed value does not live long enough

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@ -0,0 +1,13 @@
error[E0597]: borrowed value does not live long enough
--> $DIR/issue-52049.rs:16:10
|
LL | foo(&unpromotable(5u32));
| ^^^^^^^^^^^^^^^^^^ - temporary value only lives until here
| |
| temporary value does not live long enough
|
= note: borrowed value must be valid for the static lifetime...
error: aborting due to previous error
For more information about this error, try `rustc --explain E0597`.