Auto merge of #61361 - estebank:infer-type, r=varkor
Add more detail to type inference error
When encountering code where type inference fails, add more actionable
information:
```
fn main() {
let foo = Vec::new();
}
```
```
error[E0282]: type annotations needed in `std::vec::Vec<T>`
--> $DIR/vector-no-ann.rs:2:16
|
LL | let foo = Vec::new();
| --- ^^^^^^^^ cannot infer type for `T` in `std::vec::Vec<T>`
| |
| consider giving `foo` a type
```
Fix #25633.
This commit is contained in:
bors
commit
d59dcb261e
20 changed files with 136 additions and 50 deletions
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@ -4,5 +4,5 @@ fn new<T>() -> &'static T {
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fn main() {
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let &v = new();
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//~^ ERROR type annotations needed [E0282]
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//~^ ERROR type annotations needed
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}
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@ -1,11 +1,11 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `&T`
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--> $DIR/issue-12187-1.rs:6:10
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LL | let &v = new();
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| -^
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| ||
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| |cannot infer type
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| consider giving the pattern a type
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| consider giving this pattern the explicit type `&T`, with the type parameters specified
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error: aborting due to previous error
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@ -4,5 +4,5 @@ fn new<'r, T>() -> &'r T {
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fn main() {
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let &v = new();
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//~^ ERROR type annotations needed [E0282]
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//~^ ERROR type annotations needed
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}
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@ -1,11 +1,11 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `&T`
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--> $DIR/issue-12187-2.rs:6:10
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LL | let &v = new();
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| -^
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| ||
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| |cannot infer type
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| consider giving the pattern a type
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| consider giving this pattern the explicit type `&T`, with the type parameters specified
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error: aborting due to previous error
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `B<T>`
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--> $DIR/issue-17551.rs:6:15
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LL | let foo = B(marker::PhantomData);
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| --- ^ cannot infer type for `T`
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| |
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| consider giving `foo` a type
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| consider giving `foo` the explicit type `B<T>`, where the type parameter `T` is specified
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error: aborting due to previous error
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@ -1,4 +1,4 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `&(_,)`
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--> $DIR/issue-20261.rs:4:11
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LL | for (ref i,) in [].iter() {
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@ -1,8 +1,8 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `Expr<'_, VAR>`
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--> $DIR/issue-23046.rs:17:15
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LL | let ex = |x| {
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| ^ consider giving this closure parameter a type
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| ^ consider giving this closure parameter the explicit type `Expr<'_, VAR>`, where the type parameter `VAR` is specified
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error: aborting due to previous error
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@ -1,8 +1,8 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `(std::sync::mpsc::Sender<Foo<T>>, std::sync::mpsc::Receiver<Foo<T>>)`
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--> $DIR/issue-25368.rs:11:17
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LL | let (tx, rx) = channel();
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| -------- consider giving the pattern a type
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| -------- consider giving this pattern the explicit type `(std::sync::mpsc::Sender<Foo<T>>, std::sync::mpsc::Receiver<Foo<T>>)`, where the type parameter `T` is specified
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...
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LL | tx.send(Foo{ foo: PhantomData });
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| ^^^ cannot infer type for `T`
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `&[_; 0]`
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--> $DIR/issue-7813.rs:2:13
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LL | let v = &[];
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| - ^^^ cannot infer type
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| |
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| consider giving `v` a type
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| consider giving `v` the explicit type `&[_; 0]`, with the type parameters specified
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error: aborting due to previous error
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@ -22,7 +22,7 @@ impl Foo for Vec<isize> {
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fn m1() {
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// we couldn't infer the type of the vector just based on calling foo()...
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let mut x = Vec::new();
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//~^ ERROR type annotations needed [E0282]
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//~^ ERROR type annotations needed
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x.foo();
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}
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `std::vec::Vec<T>`
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--> $DIR/method-ambig-one-trait-unknown-int-type.rs:24:17
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LL | let mut x = Vec::new();
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| ----- ^^^^^^^^ cannot infer type for `T`
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| |
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| consider giving `x` a type
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| consider giving `x` the explicit type `std::vec::Vec<T>`, where the type parameter `T` is specified
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error[E0308]: mismatched types
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--> $DIR/method-ambig-one-trait-unknown-int-type.rs:33:20
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@ -1,8 +1,8 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `std::option::Option<_>`
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--> $DIR/issue-42234-unknown-receiver-type.rs:7:5
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LL | let x: Option<_> = None;
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| - consider giving `x` a type
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| - consider giving `x` the explicit type `std::option::Option<_>`, where the type parameter `T` is specified
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LL | x.unwrap().method_that_could_exist_on_some_type();
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| ^^^^^^^^^^ cannot infer type for `T`
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `[_; 0]`
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--> $DIR/cannot_infer_local_or_array.rs:2:13
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LL | let x = [];
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| - ^^ cannot infer type
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| |
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| consider giving `x` a type
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| consider giving `x` the explicit type `[_; 0]`, with the type parameters specified
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error: aborting due to previous error
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `std::vec::Vec<T>`
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--> $DIR/cannot_infer_local_or_vec.rs:2:13
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LL | let x = vec![];
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| - ^^^^^^ cannot infer type for `T`
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| |
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| consider giving `x` a type
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| consider giving `x` the explicit type `std::vec::Vec<T>`, where the type parameter `T` is specified
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `(std::vec::Vec<T>,)`
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--> $DIR/cannot_infer_local_or_vec_in_tuples.rs:2:18
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LL | let (x, ) = (vec![], );
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| ----- ^^^^^^ cannot infer type for `T`
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| |
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| consider giving the pattern a type
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| consider giving this pattern the explicit type `(std::vec::Vec<T>,)`, where the type parameter `T` is specified
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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@ -1,8 +1,8 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `std::option::Option<T>`
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--> $DIR/unboxed-closures-failed-recursive-fn-2.rs:16:32
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LL | let mut closure0 = None;
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| ------------ consider giving `closure0` a type
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| ------------ consider giving `closure0` the explicit type `std::option::Option<T>`, with the type parameters specified
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...
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LL | return c();
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| ^^^ cannot infer type
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@ -1,4 +1,4 @@
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fn main() {
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let _foo = Vec::new();
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//~^ ERROR type annotations needed [E0282]
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//~^ ERROR type annotations needed
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}
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@ -1,10 +1,10 @@
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error[E0282]: type annotations needed
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error[E0282]: type annotations needed for `std::vec::Vec<T>`
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--> $DIR/vector-no-ann.rs:2:16
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LL | let _foo = Vec::new();
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| ---- ^^^^^^^^ cannot infer type for `T`
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| |
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| consider giving `_foo` a type
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| consider giving `_foo` the explicit type `std::vec::Vec<T>`, where the type parameter `T` is specified
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error: aborting due to previous error
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