suggest `is_empty` for collections when casting to `bool`
Fixes#106883
Matches on slices, `String` and `str`. It would be nice to do this with something like `Deref<Target=str>` as well, but AFAIK it's not possible in this part of the compiler.
Consolidate two almost duplicated fn info extraction routines
Moves `extract_callable_info` up to trait selection, because it was being (almost) duplicated fully there for similar diagnostic purposes. This also generalizes the diagnostics we can give slightly (see UI test).
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 😄
Ezra Shaw