Const qualification for `StructuralEq`
Furthers #62411. Resolves#62614.
The goal of this PR is to implement the logic in #67088 on the MIR instead of the HIR. It uses the `Qualif` trait to track `StructuralPartialEq`/`StructuralEq` in the final value of a `const`. Then, if we encounter a constant during HAIR lowering whose value may not be structurally matchable, we emit the `indirect_structural_match` lint.
This PR contains all the tests present in #67088 and emits the proper warnings for the corner cases. This PR does not handle #65466, which would require that we be [more aggressive](42abbd8878/src/librustc_mir_build/hair/pattern/const_to_pat.rs (L126-L130)) when checking matched types for `PartialEq`. I think that should be done separately.
Because this works on MIR and uses dataflow, this PR should accept more cases than #67088. Notably, the qualifs in the final value of a const are encoded cross-crate, so matching on a constant whose value is defined in another crate to be `Option::<TyWithCustomEqImpl>::None` should work. Additionally, if a `const` has branching/looping, we will only emit the warning if any possible control flow path could result in a type with a custom `PartialEq` impl ending up as the final value of a `const`. I'm not sure how #67088 handled this.
AFAIK, it's not settled that these are the semantics we actually want: it's just how the `Qualif` framework happens to work. If the cross-crate part is undesirable, it would be quite easy to change the result of `mir_const_qualif().custom_eq` to `true` before encoding it in the crate metadata. This way, other crates would have to assume that all publicly exported constants may not be safe for matching.
r? @pnkfelix
cc @eddyb
Rollup of 5 pull requests
Successful merges:
- #71217 (Suggest `;` or assignment to drop borrows in tail exprs)
- #71286 (Add regression test for #69654)
- #71296 (Change wording on read_vectored docs)
- #71654 (Update link to unstable book for llvm_asm macro)
- #71657 (Add #24949 assoc constant static recursion test)
Failed merges:
r? @ghost
Change wording on read_vectored docs
Closes#70154
I'm happy to work with others to make the wording on this more clear. I think what I have is an improvement but may not be the final wording.
Suggest `;` or assignment to drop borrows in tail exprs
Address the diagnostics part of #70844.
```
error[E0597]: `counter` does not live long enough
--> $DIR/issue-54556-niconii.rs:22:20
|
LL | if let Ok(_) = counter.lock() { }
| ^^^^^^^-------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
...
LL | }
| -
| |
| `counter` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result<MutexGuard<'_>, ()>`
|
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
|
LL | if let Ok(_) = counter.lock() { };
| ^
```
Add documentation example to slice_from_raw_parts_mut()
Add SAFETY explanations to some unsafe blocks in libcore/ptr
* libcore/ptr/mod.rs
* libcore/ptr/unique.rs
* libcore/ptr/non_null.rs
safety-mod.rs: Add SAFETY to slice_from_raw_parts(),
slice_from_raw_parts_mut()
slice_from_raw_parts_mut: Add documentation example
safety-ptr-unique.rs: Add SAFETY to new() and cast()
safety-ptr-non_null.rs: Add SAFETY to new()
safety-ptr-non_null.rs: Add SAFETY to cast()
safety-ptr-non_null.rs: Add SAFETY to from() impls
safety-ptr-unique.rs: Add SAFETY to from() impls
safety-ptr-non_null.rs: Add SAFETY to new()
safety-ptr-unique.rs: Add SAFETY to new()
safety-ptr-mod.rs: Fix safety explanation
https://github.com/rust-lang/rust/pull/71507#discussion_r414488884
safety-prt-non_null.rs: Fix SAFETY comment syntax
safety-ptr-unique.rs: Fix syntax for empty()
safety-ptr-non_null.rs: Fix misuse of non-null for align_of()
safety-ptr-non_null.rs: Remove incorrect SAFETY comment
safety-ptr-unique.rs: Remove unsound SAFETY comment
safety-ptr-mod.rs: Add std comment on slice_from_raw_parts guarantee
safety-ptr-unique.rs: Remove incorrect safety comment
Creating a Unique from a NonNull has strict guarantees that the current
implementation does not guarantee
https://github.com/rust-lang/rust/pull/71507#discussion_r415035952
safety-ptr: Re-adding ignore-tidy directive
Const-prop bugfix: only add propagation inside own block for user variables
A testing spinoff of #71298. This one only adds the const-prop for locals that are user variables.
Address the diagnostics part of #70844.
```
error[E0597]: `counter` does not live long enough
--> $DIR/issue-54556-niconii.rs:22:20
|
LL | if let Ok(_) = counter.lock() { }
| ^^^^^^^-------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
...
LL | }
| -
| |
| `counter` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result<MutexGuard<'_>, ()>`
|
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
|
LL | if let Ok(_) = counter.lock() { };
| ^
```
Enable "full tools" option on ARM dist builders
This commit switches the `--enable-extended` option on the arm-related
dist builders to `--enable-full-tools`. This alias in `config.py`
corresponds to enabling a few more options:
* `rust.lld = true` - this is the main purpose of this PR, to enable LLD
on ARM-related platforms. This means it will effectively unlock
compilation of wasm programs from an arm host.
* `rust.llvm-tools = true` - it turns out that this option is largely
ignored in rustbuild today. This is only read in one location to set
some flags for the `llvm-tools` package, but the `llvm-tools` package
is already produced on all of these builders. It's predicted that this
will have no effect on build times.
* `rust.codegen-backends = ['llvm']` - historically this also enabled
the emscripten backend, but that has long since been removed.
This brings the ARM dist builders in line with the x86_64 dist builders
using this flag. The hope is that the extra time spent on CI building
LLD will acceptable because it's cached by `sccache`, LLD is a
relatively small C++ project, and the dist builders are all clocking
well under 3 hours (the slowest of all builders) around 2 hours.
There's likely some possible cleanup that can happen with these
configure options since it doesn't look like they've aged too too well,
but I'm hopeful that possible refactorings, if necessary, could be
deferred to future PRs.
