Don't emit the same compiler diagnostic twice.
This PR makes the compiler filter out diagnostic messages that have already been emitted during the same compilation session.
This commit introduces the ability to create and emit `Diagnostic`
structures from proc-macros, allowing for proc-macro authors to emit
warning, error, note, and help messages just like the compiler does.
Point at `:` when using it instead of `;`
When triggering type ascription in such a way that we can infer a
statement end was intended, add a suggestion for the change. Always
point out the reason for the expectation of a type is due to type
ascription.
Fix#42057, #41928.
Now there's a way to add suggestions that hide the suggested code when
presented inline, to avoid weird wording when short code snippets are
added at the end.
```
warning: `<` is interpreted as a start of generic arguments for `usize`, not comparison
--> $DIR/issue-22644.rs:16:33
|
16 | println!("{}", a as usize < b);
| ^ expected one of `!`, `(`, `+`, `,`, `::`, or `>` here
|
help: if you want to compare the casted value then write
| println!("{}", (a as usize) < b);
```
When the trait's span is available, it is already being used, add a
`note` for the cases where the span isn't available:
```
error[E0053]: method `fmt` has an incompatible type for trait
--> $DIR/trait_type.rs:17:4
|
17 | fn fmt(&self, x: &str) -> () { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ types differ in mutability
|
= note: expected type `fn(&MyType, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>`
found type `fn(&MyType, &str)`
error[E0050]: method `fmt` has 1 parameter but the declaration in trait `std::fmt::Display::fmt` has 2
--> $DIR/trait_type.rs:21:11
|
21 | fn fmt(&self) -> () { }
| ^^^^^ expected 2 parameters, found 1
|
= note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>`
error[E0186]: method `fmt` has a `&self` declaration in the trait, but not in the impl
--> $DIR/trait_type.rs:25:4
|
25 | fn fmt() -> () { }
| ^^^^^^^^^^^^^^^^^^ expected `&self` in impl
|
= note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>`
error[E0046]: not all trait items implemented, missing: `fmt`
--> $DIR/trait_type.rs:28:1
|
28 | impl std::fmt::Display for MyType4 {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `fmt` in implementation
|
= note: `fmt` from trait: `fn(&Self, &mut std::fmt::Formatter<'_>) -> std::result::Result<(), std::fmt::Error>`
```
