introing one-time diagnostics: only emit "lint level defined here" once
This is a revised resubmission of PR #34084 (which was closed due to inactivity on account of time constraints on the author's part).
---
We introduce a new `one_time_diagnostics` field on
`rustc::session::Session` to hold a hashset of diagnostic messages we've
set once but don't want to see again (as uniquified by span and message
text), "lint level defined here" being the motivating example dealt with
here.
This is in the matter of #24690.
---
r? @nikomatsakis
Some lint-level attributes (like `bad-style`, or, more dramatically,
`warnings`) can affect more than one lint; it seems fairer to point out
the attribute once for each distinct lint affected. Also, a UI test is
added. This remains in the matter of #24690.
Improve error message and snippet for "did you mean `x`"
- Fixes#36164
- Part of #35233
Based on the standalone example https://is.gd/8STXMd posted by @nikomatsakis and using the third formatting option mentioned in #36164 and agreed by @jonathandturner.
Note however this does not address the question of [how to handle an empty or unknown suggestion](https://github.com/rust-lang/rust/issues/36164#issuecomment-244460024). @nikomatsakis any suggestions on how best to address that part?
Fix wording for out-of-crate macro error
This fixes the wording of the note for out-of-crate macro errors to fix https://github.com/rust-lang/rust/issues/36469
The previous wording came from older logic in the PR that was replaced without updating the note.
When a type parameter shadows a primitive type, the error message
was non obvious. For example, given the file `file.rs`:
```rust
trait Parser<T> {
fn parse(text: &str) -> Option<T>;
}
impl<bool> Parser<bool> for bool {
fn parse(text: &str) -> Option<bool> {
Some(true)
}
}
fn main() {
println!("{}", bool::parse("ok").unwrap_or(false));
}
```
The output was:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool
|
= note: expected type `bool`
= note: found type `bool`
error: aborting due to previous error
```
We now show extra information about the type:
```bash
% rustc file.rs
error[E0308]: mismatched types
--> file.rs:7:14
|
7 | Some(true)
| ^^^^ expected type parameter, found bool
|
= note: expected type `bool` (type parameter)
= note: found type `bool` (bool)
error: aborting due to previous error
```
Fixes#35030
Updated e0493 to new format (+ bonus).
Part of #35233.
Fixes#35999.
r? @jonathandturner
I'm not satisfied with the bonus part, there has to be an easier way to reach into the `Drop`'s span implementation. I'm all ears. :)
Update lifetime errors to specifically note temporaries
This PR updates the error message we give in the case of a temporary value not living long enough.
Before:
<img width="497" alt="screen shot 2016-08-31 at 10 02 47 am" src="https://cloud.githubusercontent.com/assets/547158/18138551/27a06794-6f62-11e6-9ee2-bdf8bed75ca7.png">
Now:
<img width="488" alt="screen shot 2016-08-31 at 10 03 01 am" src="https://cloud.githubusercontent.com/assets/547158/18138557/2e5cf322-6f62-11e6-9047-4a78abf3d78c.png">
Specifically, it makes the following changes:
* Detects if a temporary is being used. If so, it changes the labels to mention that a temporary value specifically is in question
* Simplifies wording of the existing labels to focus on lifetimes rather than values being valid
* Changes the help to a note, since the help+span wasn't as helpful (and sometimes more confusing) than just a note.
r? @nikomatsakis
Move 'doesn't live long enough' errors to labels
This patch moves the "doesn't live long enough" region-style errors to instead use labels.
An example follows.
Before:
```
error: `x` does not live long enough
--> src/test/compile-fail/send-is-not-static-ensures-scoping.rs:26:18
|
26 | let y = &x;
| ^
|
note: reference must be valid for the block at 23:10...
--> src/test/compile-fail/send-is-not-static-ensures-scoping.rs:23:11
|
23 | fn main() {
| ^
note: ...but borrowed value is only valid for the block suffix following statement 0 at 25:18
--> src/test/compile-fail/send-is-not-static-ensures-scoping.rs:25:19
|
25 | let x = 1;
| ^
```
After:
```
error: `x` does not live long enough
--> src/test/compile-fail/send-is-not-static-ensures-scoping.rs:26:18
|
26 | let y = &x;
| ^ does not live long enough
...
32 | };
| - borrowed value only valid until here
...
35 | }
| - borrowed value must be valid until here
```
r? @nikomatsakis
