Remove `src/llvm-emscripten` submodule
With #65251 landed there's no need to build two LLVM backends and ship
them with rustc, every target we have now uses the same LLVM backend!
This removes the `src/llvm-emscripten` submodule and additionally
removes all support from rustbuild for building the emscripten LLVM
backend. Multiple codegen backend support is left in place for now, and
this is intended to be an easy 10-15 minute win on CI times by avoiding
having to build LLVM twice.
With #65251 landed there's no need to build two LLVM backends and ship
them with rustc, every target we have now uses the same LLVM backend!
This removes the `src/llvm-emscripten` submodule and additionally
removes all support from rustbuild for building the emscripten LLVM
backend. Multiple codegen backend support is left in place for now, and
this is intended to be an easy 10-15 minute win on CI times by avoiding
having to build LLVM twice.
Rename `ConstValue::Infer(InferConst::Canonical(..))` to `ConstValue::Bound(..)`
It already has the right form, so this is just a renaming. Fixes https://github.com/rust-lang/rust/issues/65655.
r? @eddyb
make is_power_of_two a const function
This makes `is_power_of_two` a const function by using `&` instead of short-circuiting `&&`; Rust supports bitwise `&` for `bool` and short-circuiting is not required in the existing expression.
I don't think this needs a const-hack label as I don't find the changed code less readable, if anything I prefer that it is clearer that short circuiting is not used.
@oli-obk
Change untagged_unions to not allow union fields with drop
This is a rebase of #56440, massaged to solve merge conflicts and make the test suite pass.
Change untagged_unions to not allow union fields with drop
Union fields may now never have a type with attached destructor. This for example allows unions to use arbitrary field types only by wrapping them in `ManuallyDrop` (or similar).
The stable rule remains, that union fields must be `Copy`. We use the new rule for the `untagged_union` feature.
Tracking issue: https://github.com/rust-lang/rust/issues/55149
Fix `canonicalize_const_var` leaking inference variables
Fixes#61338Fixes#61516Fixes#62536Fixes#64087Fixes#64863Fixes#65623
I added regression tests for all these issues apart from #64863, which is very similar to #61338.
r? @varkor
[mir-opt] Improve SimplifyLocals pass so it can remove unused consts
The `ConstProp` can cause many locals to be initialized to a constant
value and then never read from. `ConstProp` can also evaluate ZSTs into
constant values. Previously, many of these would be removed by other
parts of the MIR optimization pipeline. However, evaluating ZSTs
(especially `()`) into constant values defeated those parts of the
optimizer and so in a2e3ed5, I added a
hack to `ConstProp` that skips evaluating ZSTs to avoid that regression.
This commit changes `SimplifyLocals` so that it doesn't consider writes
of const values to a local to be a use of that local. In doing so,
`SimplifyLocals` is able to remove otherwise unused locals left behind
by other optimization passes (`ConstProp` in particular).
r? @oli-obk
Correctly note code as Ok not error for E0573
Hi, this is my first pull request to the Rust project.
The fix is very small one just to fix an oversight in a comment.
Namely, [this documentation PR](https://github.com/rust-lang/rust/pull/65234) added a longer explanation for E0573. It illustrated the error using erroneous/corrected contrasting examples. But it accidentally forgot to remove `// error` from the corrected example.
Sadly, I found the error after the PR got merged. [As suggested by the original author](https://github.com/rust-lang/rust/pull/65234/files#r336518549) of the PR, I created an PR to fix this.
Part of #61137.
