perf: UninhabitedEnumBranching avoid n^2
Avoid n² complexity. This showed up in a profile for match-stress-enum that has 8192 variants
I have only profiled locally against `match-stress-enum`, so we should have it perf tested to make sure it does not regress other crates.
The primary motivation is to get the changes from
https://github.com/tokio-rs/tracing/pull/990. Example output:
```
$ RUSTDOC_LOG=debug rustdoc +rustc2
warning: some trace filter directives would enable traces that are disabled statically
| `debug` would enable the DEBUG level for all targets
= note: the static max level is `info`
= help: to enable DEBUG logging, remove the `max_level_info` feature
```
- Remove useless test
This was testing for an ICE when passing `RUST_LOG=rustc_middle`. I
noticed it because it started giving the tracing warning (because tests
are not run with debug-logging enabled). Since this bug seems unlikely
to re-occur, I just removed it altogether.
Downgrade rc_buffer to restriction
I think Arc\<Vec\<T\>\> and Arc\<String\> and similar are a totally reasonable data structure, as observed by others in the comments on [#6044](https://github.com/rust-lang/rust-clippy/pull/6044#event-3799579830) as well. Doing `Arc::make_mut(&mut self.vec).push(...)` or `Arc::make_mut(&mut self.string).push_str("...")` is a terrific and well performing copy-on-write pattern. Linting this with an enabled-by-default <kbd>performance</kbd> lint strikes me as an unacceptable false positive balance.
As of #6090 the documentation of this lint now contains:
> **Known problems:** This pattern can be desirable ...
which should indicate that we shouldn't be linting against correct, reasonable, well-performing patterns with an enabled-by-default lint.
Mentioning #6044, #6090.
r? `@yaahc,` who reviewed the lint.
---
changelog: Remove rc_buffer from default set of enabled lints
Prevent stack overflow in deeply nested types.
Related issue #75577 (?)
Unfortunately, I am unable to test whether this actually solves the problem because apparently, 12GB RAM + 2GB swap is not enough to compile the (admittedly toy) source file.
This approach lives exclusively in the parser, so struct expr bodies
that are syntactically correct on their own but are otherwise incorrect
will still emit confusing errors, like in the following case:
```rust
fn foo() -> Foo {
bar: Vec::new()
}
```
```
error[E0425]: cannot find value `bar` in this scope
--> src/file.rs:5:5
|
5 | bar: Vec::new()
| ^^^ expecting a type here because of type ascription
error[E0214]: parenthesized type parameters may only be used with a `Fn` trait
--> src/file.rs:5:15
|
5 | bar: Vec::new()
| ^^^^^ only `Fn` traits may use parentheses
error[E0107]: wrong number of type arguments: expected 1, found 0
--> src/file.rs:5:10
|
5 | bar: Vec::new()
| ^^^^^^^^^^ expected 1 type argument
```
If that field had a trailing comma, that would be a parse error and it
would trigger the new, more targetted, error:
```
error: struct literal body without path
--> file.rs:4:17
|
4 | fn foo() -> Foo {
| _________________^
5 | | bar: Vec::new(),
6 | | }
| |_^
|
help: you might have forgotten to add the struct literal inside the block
|
4 | fn foo() -> Foo { Path {
5 | bar: Vec::new(),
6 | } }
|
```
Partially address last part of #34255.
Give `impl Trait` in a `const fn` its own feature gate
...previously it was gated under `#![feature(const_fn)]`.
I think we actually want to do this in all const-contexts? If so, this should be `#![feature(const_impl_trait)]` instead. I don't think there's any way to make use of `impl Trait` within a `const` initializer.
cc #77463
r? `@oli-obk`
Eliminate bounds checking in slice::Windows
This is how `<core::slice::Windows as Iterator>::next` looks right now:
```rust
fn next(&mut self) -> Option<&'a [T]> {
if self.size > self.v.len() {
None
} else {
let ret = Some(&self.v[..self.size]);
self.v = &self.v[1..];
ret
}
}
```
The line with `self.v = &self.v[1..];` relies on assumption that `self.v` is definitely not empty at this point. Else branch is taken when `self.size <= self.v.len()`, so `self.v` can be empty if `self.size` is zero. In practice, since `Windows` is never created directly but rather trough `[T]::windows` which panics when `size` is zero, `self.size` is never zero. However, the compiler doesn't know about this check, so it keeps the code which checks bounds and panics.
Using `NonZeroUsize` lets the compiler know about this invariant and reliably eliminate bounds checking without `unsafe` on `-O2`. Here is assembly of `Windows<'a, u32>::next` before and after this change ([goldbolt](https://godbolt.org/z/xrefzx)):
<details>
<summary>Before</summary>
```
example::next:
push rax
mov rcx, qword ptr [rdi + 8]
mov rdx, qword ptr [rdi + 16]
cmp rdx, rcx
jbe .LBB0_2
xor eax, eax
pop rcx
ret
.LBB0_2:
test rcx, rcx
je .LBB0_5
mov rax, qword ptr [rdi]
mov rsi, rax
add rsi, 4
add rcx, -1
mov qword ptr [rdi], rsi
mov qword ptr [rdi + 8], rcx
pop rcx
ret
.LBB0_5:
lea rdx, [rip + .L__unnamed_1]
mov edi, 1
xor esi, esi
call qword ptr [rip + core::slice::slice_index_order_fail@GOTPCREL]
ud2
.L__unnamed_2:
.ascii "./example.rs"
.L__unnamed_1:
.quad .L__unnamed_2
.asciz "\f\000\000\000\000\000\000\000\016\000\000\000\027\000\000"
```
</details>
<details>
<summary>After</summary>
```
example::next:
mov rcx, qword ptr [rdi + 8]
mov rdx, qword ptr [rdi + 16]
cmp rdx, rcx
jbe .LBB0_2
xor eax, eax
ret
.LBB0_2:
mov rax, qword ptr [rdi]
lea rsi, [rax + 4]
add rcx, -1
mov qword ptr [rdi], rsi
mov qword ptr [rdi + 8], rcx
ret
```
</details>
Note the lack of call to `core::slice::slice_index_order_fail` in second snippet.
#### Possible reasons _not_ to merge this PR:
* this changes the error message on panic in `[T]::windows`. However, AFAIK this messages are not covered by backwards compatibility policy.
resolve: improve "try using the enum's variant"
Fixes#73427.
This PR improves the "try using the enum's variant" suggestion:
- Variants in suggestions would not result in more errors (e.g. use of a struct variant is only suggested if the suggestion can trivially construct that variant). Therefore, suggestions are only emitted for variants that have no fields (since the suggestion can't know what value fields would have).
- Suggestions include the syntax for constructing the variant. If a struct or tuple variant is suggested, then it is constructed in the suggestion - unless in pattern-matching or when arguments are already provided.
- A help message is added which mentions the variants which are no longer suggested.
All of the diagnostic logic introduced by this PR is separated from the normal code path for a successful compilation.
r? `@estebank`
Add PartialEq impls for Vec <-> slice
This is a follow-up to #71660 and rust-lang/rfcs#2917 to add two more missing vec/slice PartialEq impls:
```
impl<A, B> PartialEq<[B]> for Vec<A> where A: PartialEq<B> { .. }
impl<A, B> PartialEq<Vec<B>> for [A] where A: PartialEq<B> { .. }
```
Since this is insta-stable, it should go through the `@rust-lang/libs` FCP process. Note that I used version 1.47.0 for the `stable` attribute because I assume this will not merge before the 1.46.0 branch is cut next week.
Rollup of 11 pull requests
Successful merges:
- #76784 (Add some docs to rustdoc::clean::inline and def_id functions)
- #76911 (fix VecDeque::iter_mut aliasing issues)
- #77400 (Fix suggestions for x.py setup)
- #77515 (Update to chalk 0.31)
- #77568 (inliner: use caller param_env)
- #77571 (Use matches! for core::char methods)
- #77582 (Move `EarlyOtherwiseBranch` to mir-opt-level 2)
- #77590 (Update RLS and Rustfmt)
- #77605 (Fix rustc_def_path to show the full path and not the trimmed one)
- #77614 (Let backends access span information)
- #77624 (Add c as a shorthand check alternative for new options #77603)
Failed merges:
r? `@ghost`
Reinstate test for forbid(clippy::restriction)
In [this commit](5747c15961) coming from rust-lang/rust (#6126) the test for `#![forbid(clippy::restriction)]` was removed because some restriction lints were being allowed after the forbid.
This change reinstates the test for `forbid` by using a separate file.
changelog: none
r? `@flip1995`
Add c as a shorthand check alternative for new options #77603
There is a missing "c" that is a shorthand for "check" in newly added match arm for handling check-specific options.
Let backends access span information
Sometimes, a backend may need to emit warnings, errors, or otherwise need to know the span of the current item in a basic block. So, add a `set_span` method to give the backend that information.
The `set_source_location` method already partially does this, however, it's disabled when debug info is disabled. There needs to be a way to unconditionally provide the span.
inliner: use caller param_env
We used the callee param env instead of the caller param env by accident in #77430, this PR fixes that and caches it in the `Inliner` struct.
fixes#77564
r? @ecstatic-morse
Update to chalk 0.31
Gonna assign @nikomatsakis to the review here, but since he is pretty busy recently, if anyone else wants to review this, that would be much appreciated.
r? @nikomatsakis
Fix suggestions for x.py setup
#76631 introduced a new `setup` command to x.py
By default the command prompts for a profile to use:
```
Welcome to the Rust project! What do you want to do with x.py?
a) Contribute to the standard library
b) Contribute to the compiler
c) Contribute to the compiler, and also modify LLVM or codegen
d) Install Rust from source
```
and then displays command suggestions, depending on which profile was chosen. However [the mapping between chosen profile](9cba260df0/src/bootstrap/setup.rs (L75-L85)) and [suggestion](9cba260df0/src/bootstrap/setup.rs (L42-L47)) isn't exact, leading to suggestions not being shown if the user presses `c` or `d`. (because "c" is translated to "llvm" and "d" to "maintainer", but suggestions trigger for "codegen" and "user" respectively)
A more thorough refactor would stop using "strings-as-type" to make sure this kind of error doesn't happen, but it may be overkill for that kind of "script" program?
Tagging the setup command author: @jyn514
Support static linking with glibc and target-feature=+crt-static
With this change, it's possible to build on a linux-gnu target and pass
RUSTFLAGS='-C target-feature=+crt-static' or the equivalent via a
`.cargo/config.toml` file, and get a statically linked executable.
Update to libc 0.2.78, which adds support for static linking with glibc.
Add `crt_static_respected` to the `linux_base` target spec.
Update `android_base` and `linux_musl_base` accordingly. Avoid enabling
crt_static_respected on Android platforms, since that hasn't been
tested.
Closes https://github.com/rust-lang/rust/issues/65447.
