Detect missing `;` on methods with return type `()`
- Point out the origin of a type requirement when it is the return type
of a method
- Point out possibly missing semicolon when the return type is `()` and
the implicit return makes sense as a statement
- Suggest changing the return type of methods with default return type
- Don't suggest changing the return type on `fn main()`
- Don't suggest changing the return type on impl fn
- Suggest removal of semicolon (instead of being help)
only set "overruled by outer forbid" once for lint groups, by group name
Previously, conflicting forbid/allow attributes for a lint group would
result in a separate "allow(L) overruled by outer forbid(L)" error for
every lint L in the group. This was needlessly and annoyingly verbose;
we prefer to just have one error pointing out the conflicting
attributes.
(Also, while we're touching context.rs, clean up some unused arguments.)
Resolves#42873.
- Point out the origin of a type requirement when it is the return type
of a method
- Point out possibly missing semicolon when the return type is () and
the implicit return makes sense as a statement
- Suggest changing the return type of methods with default return type
- Don't suggest changing the return type on fn main()
- Don't suggest changing the return type on impl fn
Previously, conflicting forbid/allow attributes for a lint group would
result in a separate "allow(L) overruled by outer forbid(L)" error for
every lint L in the group. This was needlessly and annoyingly verbose;
we prefer to just have one error pointing out the conflicting
attributes.
Resolves#42873.
Print the two types in the span label for transmute errors.
Fixes#37157. I'm not entirely happy with the changes here but overall it's better in my opinion; we certainly avoid the odd language in that issue, which changes to:
```
error[E0512]: transmute called with differently sized types: <C as TypeConstructor<'a>>::T (size can vary because of <C as TypeConstructor>::T) to <C as TypeConstructor<'b>>::T (size can vary because of <C as TypeConstructor>::T)
--> test.rs:8:5
|
8 | ::std::mem::transmute(x)
| ^^^^^^^^^^^^^^^^^^^^^ transmuting between <C as TypeConstructor<'a>>::T and <C as TypeConstructor<'b>>::T
error: aborting due to previous error(s)
```
Implement lazy loading of external crates' sources. Fixes#38875Fixes#38875. This is a follow-up to #42507. When a (now correctly translated) span from an external crate is referenced in a error, warning or info message, we still don't have the source code being referenced.
Since stuffing the source in the serialized metadata of an rlib is extremely wasteful, the following scheme has been implemented:
* File maps now contain a source hash that gets serialized as well.
* When a span is rendered in a message, the source hash in the corresponding file map(s) is used to try and load the source from the corresponding file on disk. If the file is not found or the hashes don't match, the failed attempt is recorded (and not retried).
* The machinery fetching source lines from file maps is augmented to use the lazily loaded external source as a secondary fallback for file maps belonging to external crates.
This required a small change to the expected stderr of one UI test (it now renders a span, where previously was none).
Further work can be done based on this - some of the machinery previously used to hide external spans is possibly obsolete and the hashing code can be reused in different places as well.
r? @eddyb
Report error for assignment in `if` condition
For code like `if x = 3 {}`, output:
```
error[E0308]: mismatched types
--> $DIR/issue-17283.rs:25:8
|
25 | if x = x {
| ^^^^^
| |
| help: did you mean to compare equality? `x == x`
| expected bool, found ()
|
= note: expected type `bool`
found type `()`
```
Fix#40926.
Suppress trait errors that are implied by other errors
this is currently a hack and should be cleaned up somewhat. Posting this to get some feedback.
r? @nikomatsakis
cc @estebank
Learn to parse `a as usize < b`
Parsing `a as usize > b` always works, but `a as usize < b` was a
parsing error because the parser would think the `<` started a generic
type argument for `usize`. The parser now attempts to parse as before,
and if a DiagnosticError is returned, try to parse again as a type with
no generic arguments. If this fails, return the original
`DiagnosticError`.
Fix#22644.
- generate error instead of warning
- remove `RewindPoint` and just keep a copy of `Parser` to rewind state.
- `dont_parse_generics: bool` -> `parse_generics: bool`
- remove `eat_lt`
- move error handling code to separate method
For code like `if x = 3 {}`, output:
```
error[E0308]: mismatched types
--> $DIR/issue-17283.rs:25:8
|
25 | if x = x {
| ^^^^^
| |
| help: did you mean to compare equality? `x == x`
| expected bool, found ()
|
= note: expected type `bool`
found type `()`
```
Instead of suppressing only trait errors that are "exact duplicates",
display only the "most high-level" error when there are multiple trait
errors with the same span that imply each-other.
e.g. when there are both `[closure]: Fn` and `[closure]: FnOnce`, omit
displaying the `[closure]: FnOnce` bound.
```
warning: `<` is interpreted as a start of generic arguments for `usize`, not a comparison
--> $DIR/issue-22644.rs:16:33
|
16 | println!("{}", a as usize < b);
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
help: if you want to compare the casted value then write:
| println!("{}", (a as usize) < b);
```
```
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);
```
Better closure error message
Use tracked data introduced in #42196 to provide a better closure
error message by showing why a closure implements `FnOnce`.
```
error[E0525]: expected a closure that implements the `Fn` trait, but
this closure only implements `FnOnce`
--> $DIR/issue_26046.rs:4:19
|
4 | let closure = move || {
| ___________________^
5 | | vec
6 | | };
| |_____^
|
note: closure is `FnOnce` because it moves the variable `vec` out of
its environment
--> $DIR/issue_26046.rs:5:9
|
5 | vec
| ^^^
error: aborting due to previous error(s)
```
Fixes#26046
r? @nikomatsakis
cc @doomrobo
