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Make needs_drop less pessimistic on generators

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This commit is contained in:
Jonas Schievink 2020-03-15 00:24:47 +01:00
parent 8d67f576b5
commit 50c1c295ee
4 changed files with 29 additions and 18 deletions
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15
src/test/ui/generator/borrowing.stderr
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@ -1,19 +1,16 @@
error[E0597]: `a` does not live long enough
--> $DIR/borrowing.rs:9:33
|
LL | let _b = {
| -- borrow later stored here
LL | let a = 3;
LL | Pin::new(&mut || yield &a).resume(())
| ----------^
| | |
| | borrowed value does not live long enough
| -- ^ borrowed value does not live long enough
| |
| value captured here by generator
| a temporary with access to the borrow is created here ...
LL |
LL | };
| -- ... and the borrow might be used here, when that temporary is dropped and runs the destructor for generator
| |
| `a` dropped here while still borrowed
|
= note: The temporary is part of an expression at the end of a block. Consider forcing this temporary to be dropped sooner, before the block's local variables are dropped. For example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block.
| - `a` dropped here while still borrowed
error[E0597]: `a` does not live long enough
--> $DIR/borrowing.rs:16:20

7
src/test/ui/generator/retain-resume-ref.stderr
View file

@ -4,10 +4,9 @@ error[E0499]: cannot borrow `thing` as mutable more than once at a time
LL | gen.as_mut().resume(&mut thing);
| ---------- first mutable borrow occurs here
LL | gen.as_mut().resume(&mut thing);
| ^^^^^^^^^^ second mutable borrow occurs here
LL |
LL | }
| - first borrow might be used here, when `gen` is dropped and runs the destructor for generator
| ------ ^^^^^^^^^^ second mutable borrow occurs here
| |
| first borrow later used by call
error: aborting due to previous error