Inline CStr::from_ptr
Inlining this function is valuable, as it allows LLVM to apply `strlen`-specific optimizations without having to enable LTO.
For instance, the following function:
```rust
pub fn f(p: *const c_char) -> Option<u8> {
unsafe { CStr::from_ptr(p) }.to_bytes().get(0).copied()
}
```
Looks like this if `CStr::from_ptr` is allowed to be inlined.
```asm
before:
push rax
call qword ptr [rip + std::ffi::c_str::CStr::from_ptr@GOTPCREL]
mov rcx, rax
cmp rdx, 1
sete dl
test rax, rax
sete al
or al, dl
jne .LBB1_2
mov dl, byte ptr [rcx]
.LBB1_2:
xor al, 1
pop rcx
ret
after:
mov dl, byte ptr [rdi]
test dl, dl
setne al
ret
```
Note that optimization turned this from O(N) to O(1) in terms of performance, as LLVM knows that it doesn't really need to call `strlen` to determine whether a string is empty or not.
This doesn't work properly yet, we would probably need to implement an
`assembly_neg_candidates` and consider things like `T: !AB` as `T: !A`
|| `T: !B`
Rollup of 14 pull requests
Successful merges:
- #87537 (Clarify undefined behaviour in binary heap, btree and hashset docs)
- #88624 (Stabilize feature `saturating_div` for rust 1.58.0)
- #89257 (Give better error for `macro_rules name`)
- #89665 (Ensure that pushing empty path works as before on verbatim paths)
- #89895 (Don't mark for loop iter expression as desugared)
- #89922 (Update E0637 description to mention `&` w/o an explicit lifetime name)
- #89944 (Change `Duration::[try_]from_secs_{f32, f64}` underflow error)
- #89991 (rustc_ast: Turn `MutVisitor::token_visiting_enabled` into a constant)
- #90028 (Reject closures in patterns)
- #90069 (Fix const qualification when executed after promotion)
- #90078 (Add a regression test for issue-83479)
- #90114 (Add some tests for const_generics_defaults)
- #90115 (Add test for issue #78561)
- #90129 (triagebot: Treat `I-*nominated` like `I-nominated`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
triagebot: Treat `I-*nominated` like `I-nominated`
rustbot doesn't allow unauthenticated users to set `I-nominated`; apply the same permissions to the new `I-*nominated` labels.
Add some tests for const_generics_defaults
I think this covers some of the stuff required for stabilisation report, some of these tests are probably covering stuff we already have but it can't hurt to have more :)
r? ````@lcnr````
Fix const qualification when executed after promotion
The const qualification was so far performed before the promotion and
the implementation assumed that it will never encounter a promoted.
With `const_precise_live_drops` feature, checking for live drops is
delayed until after drop elaboration, which in turn runs after
promotion. so the assumption is no longer true. When evaluating
`NeedsNonConstDrop` it is now possible to encounter promoteds.
Use type base qualification for the promoted. It is a sound
approximation in general, and in the specific case of promoteds and
`NeedsNonConstDrop` it is precise.
Fixes#89938.
rustc_ast: Turn `MutVisitor::token_visiting_enabled` into a constant
It's a visitor property rather than something that needs to be determined at runtime
Update E0637 description to mention `&` w/o an explicit lifetime name
Deal with https://github.com/rust-lang/rust/issues/89824#issuecomment-941598647. Another solution would be splitting the error code into two as (I think) it's a bit unclear to users why they have the same error code.
Don't mark for loop iter expression as desugared
We typically don't mark spans of lowered things as desugared. This helps Clippy rightly discern when code is (not) from expansion. This was discovered by ``@flip1995`` at https://github.com/rust-lang/rust-clippy/pull/7789#issuecomment-939289501.
Stabilize feature `saturating_div` for rust 1.58.0
The tracking issue is #89381
This seems like a reasonable simple change(?). The feature `saturating_div` was added as part of the ongoing effort to implement a `Saturating` integer type (see #87921). The implementation has been discussed [here](https://github.com/rust-lang/rust/pull/87921#issuecomment-899357720) and [here](https://github.com/rust-lang/rust/pull/87921#discussion_r691888556). It extends the list of saturating operations on integer types (like `saturating_add`, `saturating_sub`, `saturating_mul`, ...) by the function `fn saturating_div(self, rhs: Self) -> Self`.
The stabilization of the feature `saturating_int_impl` (for the `Saturating` type) needs to have this stabilized first.
Closes#89381
Clarify undefined behaviour in binary heap, btree and hashset docs
Previously, it wasn't clear whether "This could include" was referring to logic errors, or undefined behaviour. Tweak wording to clarify this sentence does not relate to UB.
This addresses a TODO comment. The behavior of #[derive(Clone)]
*does* result in a T: Clone requirement.
Add a manual Clone implementation, matching Split and SplitInclusive.
Previously, it wasn't clear whether "This could include" was referring
to logic errors, or undefined behaviour. Tweak wording to clarify this
sentence does not relate to UB.
