Add suggestion `.collect()` for iterators in iterators
Closes#81584
```
error[E0515]: cannot return value referencing function parameter `y`
--> main3.rs:4:38
|
4 | ... .map(|y| y.iter().map(|x| x + 1))
| -^^^^^^^^^^^^^^^^^^^^^^
| |
| returns a value referencing data owned by the current function
| `y` is borrowed here
| help: Maybe use `.collect()` to allocate the iterator
```
Added the suggestion: `help: Maybe use `.collect()` to allocate the iterator`
resolve: Reduce scope of `pub_use_of_private_extern_crate` deprecation lint
This lint was deny-by-default since July 2017, crater showed 7 uses on crates.io back then (https://github.com/rust-lang/rust/pull/42894#issuecomment-311921147).
Unfortunately, the construction `pub use foo as bar` where `foo` is `extern crate foo;` was used by an older version `bitflags`, so turning it into an error causes too many regressions.
So, this PR reduces the scope of the lint instead of turning it into a hard error, and only turns some more rarely used components of it into errors.
Implement NOOP_METHOD_CALL lint
Implements the beginnings of https://github.com/rust-lang/lang-team/issues/67 - a lint for detecting noop method calls (e.g, calling `<&T as Clone>::clone()` when `T: !Clone`).
This PR does not fully realize the vision and has a few limitations that need to be addressed either before merging or in subsequent PRs:
* [ ] No UFCS support
* [ ] The warning message is pretty plain
* [ ] Doesn't work for `ToOwned`
The implementation uses [`Instance::resolve`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/instance/struct.Instance.html#method.resolve) which is normally later in the compiler. It seems that there are some invariants that this function relies on that we try our best to respect. For instance, it expects substitutions to have happened, which haven't yet performed, but we check first for `needs_subst` to ensure we're dealing with a monomorphic type.
Thank you to ```@davidtwco,``` ```@Aaron1011,``` and ```@wesleywiser``` for helping me at various points through out this PR ❤️.
Inherit `#[stable(..)]` annotations in enum variants and fields from its item
Lint changes for #65515. The stdlib will have to be updated once this lands in beta and that version is promoted in master.
This ownership kind is only constructed in the case of path attributes like `#[path = ".."]` without a file name segment, which always represent some kind of directories and will produce and error on attempt to parse them as a module file.
Upgrade to LLVM 12
This implements the necessary adjustments to make rustc work with LLVM 12. I didn't encounter any major issues so far.
r? `@cuviper`
We previously used -Os to disable this pass, but since
https://reviews.llvm.org/D91673 this no longer works. Explicitly
disable it using -Cllvm-args instead.
Revert non-power-of-two vector restriction
Removes the power of two restriction from rustc. As discussed in https://github.com/rust-lang/stdsimd/issues/63
r? ```@calebzulawski```
cc ```@workingjubilee``` ```@thomcc```
- Use spans for deprecated attributes
- Use a proper diagnostic for unknown passes, instead of error logging
- Add tests for unknown passes
- Improve some wording in diagnostics
