Split non macro portion of unused_doc_comment from macro part into two passes/lints
## Motivation
This change is motivated by the needs of the [spandoc library](https://github.com/yaahc/spandoc). The specific use case is that my macro is removing doc comments when an attribute is applied to a fn with doc comments, but I would like the lint to still appear when I forget to add the `#[spandoc]` attribute to a fn, so I don't want to have to silence the lint globally.
## Approach
This change splits the `unused _doc_comment` lint into two lints, `unused_macro_doc_comment` and `unused_doc_comment`. The non macro portion is moved into an `early_lint_pass` rather than a pre_expansion_pass. This allows proc macros to silence `unused_doc_comment` warnings by either adding an attribute to silence it or by removing the doc comment before the early_pass runs.
The `unused_macro_doc_comment` lint however will still be impossible for proc-macros to silence, but the only alternative that I can see is to remove this lint entirely, which I don't think is acceptable / is a decision I'm not comfortable making personally, so instead I opted to split the macro portion of the check into a separate lint so that it can be silenced globally with an attribute if necessary without needing to globally silence the `unused_doc_comment` lint as well, which is still desireable.
fixes https://github.com/rust-lang/rust/issues/67838
parse: allow `type Foo: Ord` syntactically
This addresses:
> (Work still remains to fuse this with free type aliases, but this can be done later.)
in https://github.com/rust-lang/rust/pull/69194.
r? @petrochenkov
Rollup of 7 pull requests
Successful merges:
- #68984 (Make `u8::is_ascii` a stable `const fn`)
- #69339 (Add test for #69312)
- #69346 (Clean up E0323, E0324, E0325 and E0326 explanations)
- #69348 (Wrong error message for move_ref_pattern)
- #69349 (MIR is not an experiment anymore)
- #69354 (Test `Duration::new` panics on overflow)
- #69370 (move const_eval.rs into the module folder)
Failed merges:
r? @ghost
Wrong error message for move_ref_pattern
The current error message states that move occurs *because of `Copy`*:
```Rust
"move occurs because `{}` has type `{}` which does implement the `Copy` trait."
```
I found this randomly when surfing through the sources. This means, I don't have any context and might be completely wrong.
r? @Centril
Make `u8::is_ascii` a stable `const fn`
`char::is_ascii` was already stabilized as `const fn` in #55278, so there is no reason for `u8::is_ascii` to go through an unstable period.
cc @rust-lang/libs
Revert #69280Resolves#69313 by reverting #69280.
After #69280, `#[rustc_args_required_const(2)]` is required on the declaration of `simd_shuffle` intrinsics. This is allowed breakage, since you can't define platform intrinsics on stable. However, the latest release of the widely used `packed_simd` crate defines these intrinsics without the requisite attribute. Since there's no urgency to merge #69280, let's revert it. We can reconsider when rust-lang/packed_simd#278 is included in a point release of `packed_simd`.
r? @petrochenkov
Tweak binding lifetime suggestion text
We already have a structured suggestion, but the wording made it seem like that wasn't the case.
Fix#65286. r? @varkor
Unify and improve const-prop lints
Add a single helper method for all lints emitted by const-prop, and make that lint different from the CTFE `const_err` lint. Also consistently check overflow on *arithmetic*, not on the assertion, to make behavior the same for debug and release builds.
See [this summary comment](https://github.com/rust-lang/rust/pull/69185#issuecomment-587924754) for details and the latest status.
In terms of lint formatting, I went for what seems to be the better style: have a general message above the code, and then a specific message at the span:
```
error: this arithmetic operation will overflow
--> $DIR/const-err2.rs:21:18
|
LL | let a_i128 = -std::i128::MIN;
| ^^^^^^^^^^^^^^^ attempt to negate with overflow
```
We could also just have the specific message above and no text at the span if that is preferred.
I also converted some of the existing tests to use compiletest revisions, so that the same test can check a bunch of different compile flags.
Fixes https://github.com/rust-lang/rust/issues/69020.
Helps with https://github.com/rust-lang/rust/issues/69021: debug/release are now consistent, but the assoc-const test in that issue still fails (there is a FIXME in the PR for this). The reason seems to be that const-prop notices the assoc const in `T::N << 42` and does not even bother calling `const_prop` on that operation.
Has no effect on https://github.com/rust-lang/rust/issues/61821; the duplication there has entirely different reasons.
Make integer exponentiation methods unstably const
cc #53718
This makes the following inherent methods on integer primitives into unstable `const fn`:
- `pow`
- `checked_pow`
- `wrapping_pow`
- `overflowing_pow`
- `saturating_pow`
- `next_power_of_two`
- `checked_next_power_of_two`
- `wrapping_next_power_of_two`
Only two changes were made to the implementation of these methods. First, I had to switch from the `?` operator, which is not yet implemented in a const context, to a `try_opt` macro. Second, `next_power_of_two` was using `ops::Add::add` (see the first commit) to "get overflow checks", so I switched to `#[rustc_inherit_overflow_checks]`. I'm not quite sure why the attribute wasn't used in the first place.
Allow trait methods to be called on concrete types in a const context
This partially implements [RFC 2632](https://github.com/rust-lang/rfcs/pull/2632) by const-checking methods inside an `impl const` block and allowing those methods to be called on concrete types. Calling trait methods on type parameters in a const context is not yet allowed. Implementing this will require much more work. Since we are only concerned with methods on concrete types, we are able to take advantage of the machinery in `Instance::resolve`, which is doing most of the work.
This also propagates `#[rustc_const_unstable]` from parent items to child items, making that attribute behave like `#[stable]` and `#[unstable]` do. This allows trait methods to be marked as unstably const.
cc #67792#57563
cc @rust-lang/wg-const-eval
r? @oli-obk
Remove special case for `simd_shuffle` arg promotion
After rust-lang/stdarch#825, these intrinsics are now defined with `#[rustc_args_required_const(2)]`, so the special-case is no longer necessary.
