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Report "nice" placeholder errors more often

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If we have a cause containing `ValuePairs::PolyTraitRefs` but neither
TraitRef has any escaping bound regions then we report the same error as
for `ValuePairs::TraitRefs`.
This commit is contained in:
Matthew Jasper 2021-02-09 22:59:32 +00:00
parent daab6db1a0
commit 94c11dfe78
19 changed files with 181 additions and 263 deletions
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2
src/test/ui/issues/issue-57843.nll.stderr
View file

@ -1,5 +1,5 @@
error: higher-ranked subtype error
--> $DIR/issue-57843.rs:23:9
--> $DIR/issue-57843.rs:25:9
|
LL | Foo(Box::new(|_| ()));
| ^^^^^^^^^^^^^^^^

6
src/test/ui/issues/issue-57843.rs
View file

@ -11,7 +11,9 @@ trait ClonableFn<T> {
}
impl<T, F: 'static> ClonableFn<T> for F
where F: Fn(T) + Clone {
where
F: Fn(T) + Clone,
{
fn clone(&self) -> Box<dyn Fn(T)> {
Box::new(self.clone())
}
@ -20,5 +22,5 @@ where F: Fn(T) + Clone {
struct Foo(Box<dyn for<'a> ClonableFn<&'a bool>>);
fn main() {
Foo(Box::new(|_| ())); //~ ERROR mismatched types
Foo(Box::new(|_| ())); //~ ERROR implementation of `FnOnce` is not general enough
}

16
src/test/ui/issues/issue-57843.stderr
View file

@ -1,17 +1,11 @@
error[E0308]: mismatched types
--> $DIR/issue-57843.rs:23:9
error: implementation of `FnOnce` is not general enough
--> $DIR/issue-57843.rs:25:9
|
LL | Foo(Box::new(|_| ()));
| ^^^^^^^^^^^^^^^^ one type is more general than the other
| ^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
|
= note: expected type `FnOnce<(&'a bool,)>`
found type `FnOnce<(&bool,)>`
note: this closure does not fulfill the lifetime requirements
--> $DIR/issue-57843.rs:23:18
|
LL | Foo(Box::new(|_| ()));
| ^^^^^^
= note: `[closure@$DIR/issue-57843.rs:25:18: 25:24]` must implement `FnOnce<(&'1 bool,)>`, for any lifetime `'1`...
= note: ...but it actually implements `FnOnce<(&'2 bool,)>`, for some specific lifetime `'2`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.