Suggestion for type mismatch when we need a u8 but the programmer wrote a char literal
Today Rust just points out that we have a char and we need a u8, but if I wrote 'A' then I could fix this by just writing b'A' instead. This code should detect the case where we're about to report a type mismatch of this kind, and the programmer wrote a char literal, and the char they wrote is ASCII, so therefore just prefixing b to make a byte literal will do what they meant.
I have definitely written this mistake more than once, it's not difficult to figure out what to do, but the compiler might as well tell us anyway.
I provided a test with two simple examples where the suggestion is appropriate, and one where it is not because the char literal is not ASCII, showing that the suggestion is only triggered in the former cases.
I have contributed only a small typo doc fix before, so this is my first substantive rustc change.
Emit a hint for bad call return types due to generic arguments
When the return type of a function call depends on the type of an argument, e.g.
```
fn foo<T>(x: T) -> T {
x
}
```
and the expected type is set due to either an explicitly typed binding, or because the call to the function is in a tail position without semicolon, the current error implies that the argument in the call has the wrong type.
This new hint highlights that the expected type doesn't match the returned type, which matches the argument type, and that that's why we're flagging the argument type.
Fixes#43608.
Add note when `FnPtr` vs. `FnDef` impl trait
I encountered an instance where an `FnPtr` implemented a trait, but I was passing an `FnDef`. I was confused for an hour and to examine the source code of the trait's crate's tests in order to understand how to cast it properly (it didn't help that it was behind a reference). To the end user, it might not be immediately obvious that they are different and how to convert from an `FnDef` to an `FnPtr`, but it is necessary to cast to the generic function in order to compile. It is thus useful to suggest `as` in the help note, (even if the `Fn` output implements the trait).
Emit a single error for contiguous sequences of unknown tokens
Closes#106101
On encountering a sequence of identical source characters which are unknown tokens, note the amount of subsequent characters and advance past them silently. The old behavior was to emit an error and 'help' note for every single one.
`@rustbot` label +A-diagnostics +A-parser
I encountered an instance where an `FnPtr` implemented a trait, but I was passing an `FnDef`. To
the end user, there is really no way to differentiate each of them, but it is necessary to cast
to the generic function in order to compile. It is thus useful to suggest `as` in the help note,
(even if the Fn output implements the trait).
Update `rental` hack to work with remapped paths.
This PR simply switches to an already-existing helper instead of hard-coding a specific enum variant. The new revision of the test fails without the other changes in this PR.
Context: I'm exploring running UI tests with remapped paths by default in #105924 and the rental test was one of the ones that failed.
This may also be useful in the context of https://github.com/rust-lang/rfcs/pull/3127 ("New rustc and Cargo options to allow path sanitisation by default").
Normalize test output more thoroughly
This prevents differences in local environments, which may (for example) end up with a longer backtrace with more digits in the backtrace prefix, as happened to me. While we're at it, clean more of the output up, including the exact location of the error in the compiler.
cc https://github.com/rust-lang/rust/pull/106521 which introduced this test
Warn when using panic-strategy abort for proc-macro crates
See https://github.com/rust-lang/rust/issues/82320, this simply warns for now as that seems like the best step that can be immediately taken (opposed to straight up rejecting or ignoring)
Bump `IMPLIED_BOUNDS_ENTAILMENT` to Deny + ReportNow
https://github.com/rust-lang/rust/pull/105575#issuecomment-1357201969
> and then later in the same cycle increase the lint to `deny` and change it to `FutureCompatReportNow` in this nightly cycle.
r? ```@lcnr``` when they're back from holiday 😄
Add log-backtrace option to show backtraces along with logging
according to #90698, I added a compiler option, `-Zlog-backtrace=filter`, where `filter` is a module name, to show backtraces for logging without rebuilding.
resolve#90698
Render missing generics suggestion verbosely
It's a bit easier to read like this, especially ones that are appending new generics onto an existing list, like ": `, T`" which render somewhat poorly inline.
Also don't suggest `dyn` as a type parameter to add, even if technically that's valid in edition 2015.
When the return type of a function call depends on the type of an
argument, e.g.
```
fn foo<T>(x: T) -> T {
x
}
```
and the expected type is set due to either an explicitly typed
binding, or because the call to the function is in a tail position
without semicolon, the current error implies that the argument in the
call has the wrong type.
This new hint highlights that the expected type doesn't match the
returned type, which matches the argument type, and that that's why
we're flagging the argument type.
Fixes#43608.
This prevents differences in local environments, which may (for example)
end up with a longer backtrace with more digits in the backtrace prefix,
as happened to me. While we're at it, clean more of the output up,
including the exact location of the error in the compiler.
Revert "Make nested RPITIT inherit the parent opaque's generics."
This reverts commit e2d41f4c97, and adjusts the `tests/ui/async-await/in-trait/nested-rpit.rs` test.
r? `@cjgillot`
fixes#106332, manually verified because it had no minimization :/
reopens#105197
cc #106729
Mark ZST as FFI-safe if all its fields are PhantomData
This presents one possible solution to issue: #106629.
This is my first (tentative) contribution to the compiler itself.
I'm looking forward for comments and feedback
Closes: #106629
Handle inference variables in `CollectAllMismatches` correctly
1. Fix#106240
2. Treat int/float type variables correctly (see `src/test/ui/iterators/invalid-iterator-chain-with-int-infer.rs`), so we can point out things like "`Iterator::Item` changed to `{integer}` here"
Migrate mir_build diagnostics 2 of 3
The first three commits are fairly boring, however I've made some changes to the output of the match checking diagnostics.
Stabilize `::{core,std}::pin::pin!`
As discussed [over here](https://github.com/rust-lang/rust/issues/93178#issuecomment-1295843548), it looks like a decent time to stabilize the `pin!` macro.
### Public API
```rust
// in module `core::pin`
/// API: `fn pin<T>($value: T) -> Pin<&'local mut T>`
pub macro pin($value:expr $(,)?) {
…
}
```
- Tracking issue: #93178
(now all this needs is an FCP by the proper team?)
Allow codegen to unsize `dyn*` to `dyn`
`dyn* Trait` is just another type that implements `Trait`, so we should be able to unsize `&dyn* Trait` into `&dyn Trait` perfectly fine, same for `Box` and other unsizeable types.
Fixes#106488
Prefer non-`[type error]` candidates during selection
Fixes#102130Fixes#106351
r? types
note: Alternatively we could filter out error where-clauses during param-env construction? But we still need to filter out impls with errors during `match_impl`, I think.
Fix invalid syntax and incomplete suggestion in impl Trait parameter type suggestions for E0311
Fixes#105544
The problems: The suggestion given for E0311 has invalid syntax when the synthetic type parameter is used for Trait type in function declaration:
```rust
fn foo(d: impl Sized) -> impl Sized
```
instead of explicitly specified like the following:
```rust
fn foo<T: Sized>(d: T) -> impl Sized
```
In addition to the syntax error, the suggestions given for E0311 are not complete when multiple elided lifetimes are involved in lifetime bounds, not all involved parameters are given the named lifetime in the suggestions. For the following test case:
```
fn foo(d: impl Sized, p: &mut ()) -> impl Sized + '_ {
(d, p)
}
```
a good suggestion should add the lifetime 'a to both d and p, instead of d only:
```
fn foo<'a>(d: impl Sized + 'a, p: &'a mut ()) -> impl Sized + '_ {
(d, p)
}
```
The Solution: Fix the syntax problem in the suggestions when synthetic type parameter is used, and also add lifetimes for all involved parameters.
Recover from where clauses placed before tuple struct bodies
Open to any suggestions regarding the phrasing of the diagnostic.
Fixes#100790.
`@rustbot` label A-diagnostics
r? diagnostics
Note predicate span on `ImplDerivedObligation`
Seems obvious to point out the where-clause that introduces the `ImplDerivedObligation` :)
r? `@estebank`
