rustc_typeck: improve diagnostics for -> _ fn return type
This should implement IIUC the mentioned issue.
~~I'm not sure if there is a better way than `get_infer_ret_ty` to get/check the return type without code duplication.~~
~~Also, is this unwrap be okay `ty::Binder::bind(*tables.liberated_fn_sigs().get(hir_id).unwrap())`?~~
r? @eddyb
Closes: https://github.com/rust-lang/rust/issues/56132
Raise the default recursion limit to 128
The previous limit of 64 is being (just) barely hit by genuine code out there, which is causing issues like https://github.com/rust-lang/rust/issues/62059 to rear their end.
Ideally, we wouldn’t have such arbitrary limits at all, but while we do, it makes a lot of sense to just raise this limit whenever genuine use-cases end up hitting it.
r? @pnkfelix
Fixes https://github.com/rust-lang/rust/issues/62059
Improve the explicit_outlives_requirements lint
* Don't use Strings to compare parameters
* Extend the lint to lifetime bounds
* Extend the lint to enums and unions
* Use the correct span for where clauses in tuple structs
* Try to early-out where possible
* Remove unnecessary bounds in rustc crates
Refactor C FFI variadics to more closely match their C counterparts, and add Clone implementation
We had to make some changes to expose `va_copy` and `va_end` directly to users (mainly for C2Rust, but not exclusively):
- redefine the Rust variadic structures to more closely correspond to C: `VaList` now matches `va_list`, and `VaListImpl` matches `__va_list_tag`
- add `Clone` for `VaListImpl`
- add explicit `as_va_list()` conversion function from `VaListImpl` to `VaList`
- add deref coercion from `VaList` to `VaListImpl`
- add support for the `asmjs` target
All these changes were needed for use cases like:
```Rust
let mut ap2 = va_copy(ap);
vprintf(fmt, ap2);
va_end(&mut ap2);
```
Point at individual type args on arg count mismatch
- Point at individual type arguments on arg count mismatch
- Make generics always have a valid span, even when there are no args
- Explain that `impl Trait` introduces an implicit type argument
Fix#55991.
Warn on bare_trait_objects by default
The `bare_trait_objects` lint is set to `warn` by default.
Most ui tests have been updated to use `dyn` to avoid creating noise in stderr files.
r? @Centril
cc #54910
Warn when ignore-tidy-linelength is present, but no lines are too long
It's easy for a `// ignore-tidy-linelength` to be added when there is a genuine need to ignore a file's line length, but then after refactoring the need is gone, but the tidy directive is not removed. This means that in the future, further editing may accidentally add unnecessarily long lines. This change forces `// ignore-tidy-linelength` to be used exactly when necessary, to make sure such changes are intentional.
