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Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#143467 (Add ASCII-related methods from `u8` and `MIN`/`MAX` to `core::ascii::Char`)
- rust-lang/rust#144519 (Constify `SystemTime` methods)
- rust-lang/rust#144642 (editorconfig: don't trim trailing whitespace in tests)
- rust-lang/rust#144870 (Stabilize `path_file_prefix` feature)
- rust-lang/rust#145269 (Deprecate RUST_TEST_* env variables)
- rust-lang/rust#145274 (Remove unused `#[must_use]`)
- rust-lang/rust#145289 (chore(ci): upgrade checkout to v5)
- rust-lang/rust#145303 (Docs: Link to payload_as_str() from payload().)
- rust-lang/rust#145308 (Adjust documentation of `dangling`)
- rust-lang/rust#145320 (Allow cross-compiling the Cranelift dist component)
- rust-lang/rust#145325 (Add `cast_init` and `cast_uninit` methods for pointers)
r? `@ghost`
`@rustbot` modify labels: rollup
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Remove unused `#[must_use]`
Self-explanatory
Fixes https://github.com/rust-lang/rust/issues/145257
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Set dead_on_return attribute for indirect arguments
Set the dead_on_return attribute (added in LLVM 21) for arguments that are passed indirectly, but not byval.
This indicates that the value of the argument on return does not matter, enabling additional dead store elimination.
From LangRef:
> This attribute indicates that the memory pointed to by the argument is dead upon function return, both upon normal return and if the calls unwinds, meaning that the caller will not depend on its contents. Stores that would be observable either on the return path or on the unwind path may be elided.
>
> Specifically, the behavior is as-if any memory written through the pointer during the execution of the function is overwritten with a poison value upon function return. The caller may access the memory, but any load not preceded by a store will return poison.
>
> This attribute does not imply aliasing properties. For pointer arguments that do not alias other memory locations, noalias attribute may be used in conjunction. Conversely, this attribute always implies dead_on_unwind.
>
> This attribute cannot be applied to return values.
This fixes parts of https://github.com/rust-lang/rust/issues/96497.
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In the desugaring of `assert!`, we now expand to a `match` expression
instead of `if !cond {..}`.
The span of incorrect conditions will point only at the expression, and not
the whole `assert!` invocation.
```
error[E0308]: mismatched types
--> $DIR/issue-14091.rs:2:13
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LL | assert!(1,1);
| ^ expected `bool`, found integer
```
We no longer mention the expression needing to implement the `Not` trait.
```
error[E0308]: mismatched types
--> $DIR/issue-14091-2.rs:15:13
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LL | assert!(x, x);
| ^ expected `bool`, found `BytePos`
```
`assert!(val)` now desugars to:
```rust
match val {
true => {},
_ => $crate::panic::panic_2021!(),
}
```
Fix #122159.
We make some minor changes to some diagnostics to avoid span overlap on
type mismatch or inverted "expected"/"found" on type errors.
We remove some unnecessary parens from core, alloc and miri.
address review comments
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This eliminates the case in `failed_to_match_macro` to check for a
function-like invocation of a macro with no function-like rules.
Instead, macro kind mismatches now result in an unresolved macro, and we
detect this case in `unresolved_macro_suggestions`, which now carefully
distinguishes between a kind mismatch and other errors.
This also handles cases of forward-referenced attributes and cyclic
attributes.
Expand test coverage to include all of these cases.
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Make no_mangle on foreign items explicit instead of implicit
for a followup PR I'm working on I need some foreign items to mangle. I could add a new attribute: `no_no_mangle` or something silly like that but by explicitly putting `no_mangle` in the codegen fn attrs of foreign items we can default it to `no_mangle` and then easily remove it when we don't want it.
I guess you'd know about this r? `@bjorn3.` Shouldn't be too hard to review :)
Builds on rust-lang/rust#144655 which should merge first.
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Support using #[unstable_feature_bound] on trait
This is needed to unblock https://github.com/rust-lang/rust/pull/145095
r? ```````@BoxyUwU```````
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Tweak invalid builtin attribute output
- Add link to reference/docs when possible
- More accurate suggestions by supporting multiple alternative suggestions
```
error: malformed `crate_type` attribute input
--> $DIR/crate-type-macro-call.rs:1:1
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LL | #![crate_type = foo!()]
| ^^^^^^^^^^^^^^^^^^^^^^^
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= note: for more information, visit <https://doc.rust-lang.org/reference/linkage.html>
help: the following are the possible correct uses
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LL - #![crate_type = foo!()]
LL + #![crate_type = "bin"]
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LL - #![crate_type = foo!()]
LL + #![crate_type = "cdylib"]
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LL - #![crate_type = foo!()]
LL + #![crate_type = "dylib"]
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LL - #![crate_type = foo!()]
LL + #![crate_type = "lib"]
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= and 4 other candidates
```
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rustdoc: correct negative-to-implicit discriminant display
This PR want to fix rust-lang/rust#145125
In:
https://github.com/rust-lang/rust/blob/7f7b8ef27d86c865a7ab20c7c42f50811c6a914d/compiler/rustc_middle/src/ty/util.rs#L33-L38
the `Discr`'s `val` field is `u128`, so we can't use `discr.val as i128` to represent `Discr`'s signed value.
We should use `Discr`'s `Display` trait to display signed value.
https://github.com/rust-lang/rust/blob/7f7b8ef27d86c865a7ab20c7c42f50811c6a914d/compiler/rustc_middle/src/ty/util.rs#L60-L73
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fix: re-enable self-assignment
## Description
Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`.
## History
The original regressions (rust-lang/rust#81626, rust-lang/rust#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand.
- Self-assignment detection was originally implemented in rust-lang/rust#87129 to address rust-lang/rust#75356
- The implementation was disabled alongside the revert of rust-lang/rust#81473's "write-only fields" detection
- rust-lang/rust#81473 was reverted via rust-lang/rust#86212 and rust-lang/rust#83171 due to false positives in write-only field detection (rust-lang/rust#81626, rust-lang/rust#81658)
- The self-assignment detection feature got removed, even though it wasn't the reason for the problems
This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis.
## Changes
- Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file
- `handle_assign` and
- `check_for_self_assign`
- Added `ExprKind::Assign` handling in `visit_expr` to call both methods
- Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
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Port `#[allow_internal_unsafe]` to the new attribute system (attempt 2)
This is a slightly modified version of ae1487aa9922de7642c448cc0908584026699e1c, which caused a performance regression (reverted in https://github.com/rust-lang/rust/pull/145086#issue-3303428759). The diff between this PR and the previous one can be seen in 027a1def.
r? ```````@jdonszelmann``````` :sparkling_heart:
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r=fmease,GuillaumeGomez
Don't emit `rustdoc::broken_intra_doc_links` for GitHub-flavored Markdown admonitions like `[!NOTE]`
fixes rust-lang/rust#141866
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Extract TraitImplHeader in AST/HIR
Several fields of `Impl` are only applicable when it's a trait impl. This moves those fields into a new struct that is only present for trait impls.
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Apple: Always pass SDK root when linking with `cc`, and pass it via `SDKROOT` env var
Fixes https://github.com/rust-lang/rust/issues/80817, fixes https://github.com/rust-lang/rust/issues/96943, and generally simplifies our linker invocation on Apple platforms.
Part of https://github.com/rust-lang/rust/issues/129432.
### Necessary background on trampoline binaries
The developer binaries such as `/usr/bin/cc` and `/usr/bin/clang` are actually trampolines (similar in spirit to the Rust binaries in `~/.cargo/bin`) which effectively invokes `xcrun` to get the current Xcode developer directory, which allows it to find the actual binary under `/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/*`.
This binary is then launched with the following environment variables set (but none of them are set if `SDKROOT` is set explicitly):
- `SDKROOT=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk`
- `LIBRARY_PATH=/usr/local/lib` (appended)
- `CPATH=/usr/local/include` (appended)
- `MANPATH=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/share/man:/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/usr/share/man:/Applications/Xcode.app/Contents/Developer/usr/share/man:/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/share/man:` (prepended)
This allows the user to type e.g. `clang foo.c` in their terminal on macOS, and have it automatically pick up a suitable Clang binary and SDK from either an installed Xcode.app or the Xcode Command Line Tools.
(It acts roughly as-if you typed `xcrun -sdk macosx clang foo.c`).
### Finding a suitable SDK
All compilation on macOS is cross-compilation using SDKs, there are no system headers any more (`/usr/include` is gone), and the system libraries are elsewhere in the file system (`/usr/lib` is basically empty). Instead, the logic for finding the SDK is handled by the `/usr/bin/cc` trampoline (see above).
But relying on the `cc` trampoline doesn't work when:
- Cross-compiling, since a different SDK is needed there.
- Invoking the linker directly, since the linker doesn't understand `SDKROOT`.
- Linking build scripts inside Xcode (see https://github.com/rust-lang/rust/issues/80817), since Xcode prepends `/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin` to `PATH`, which means `cc` refers to the _actual_ Clang binary, and we end up with the wrong SDK root specified.
Basically, we cannot rely on the trampoline at all, so the last commit removes the special-casing that was done when linking with `cc` for macOS (i.e. the most common path), so that **we now always invoke `xcrun` (if `SDKROOT` is not explicitly specified) to find the SDK root**.
Making sure this is non-breaking has a few difficulties though, namely that the user might not have Xcode installed, and that the compiler driver may not understand the `-isysroot` flag. These difficulties are explored below.
#### No Xcode
There are several compiler drivers which work without Xcode by bundling their own SDK, including `zig cc`, Nixpkgs' `clang` and Homebrew's `llvm` package. Additionally, `xcrun` is rarely available when cross-compiling from non-macOS and instead the user might provide a downloaded SDK manually with `-Clink-args=...`.
We do still want to _try_ to invoke `xcrun` if possible, since it is usually the SDK that the user wants (and if not, the environment should override `xcrun`, such as is done by Nixpkgs). But we do not want failure to invoke `xcrun` to stop the linking process. This is changed in the second-to-last commit.
#### `SDKROOT` vs. `-isysroot`
The exact reasoning why we do not always pass the SDK root when linking on macOS eludes me (the git history dead ends in rust-lang/rust#100286), but I suspect it's because we want to support compiler drivers which do not support the `-isysroot` option.
To make sure that such use-cases continue to work, we now pass the SDK root via the `SDKROOT` environment variable. This way, compiler drivers that support setting the SDK root (such as Clang and GCC) can use it, while compiler drivers that don't (presumably because they figure out the SDK in some other way) can just ignore it.
One small danger here would be if there's some compiler driver out there which works with the `-isysroot` flag, but not with the `SDKROOT` environment variable. I am not aware of any?
In a sense, this also shifts the blame; if a compiler driver does not understand `SDKROOT`, it won't work with e.g. `xcrun -sdk macosx15.0 $tool` either, so it can more clearly be argued that this is incorrect behaviour on the part of the tool.
Note also that this overrides the behaviour discussed above (`/usr/bin/cc` sets some extra environment variables), I will argue that is fine since `MANPATH` and `CPATH` is useless when linking, and `/usr/local/lib` is empty on a default system at least since macOS 10.14 (it might be filled by extra libraries installed by the user, but I'll argue that if we want it to be part of the default library search path, we should set it explicitly so that it's also set when linking with `-Clinker=ld`).
### Considered alternatives
- Invoke `/usr/bin/cc` instead of `cc`.
- This breaks many other use-cases though where overriding `cc` in the PATH is desired.
- Look up `which cc`, and do special logic if in Xcode toolchain.
- Seems brittle, and besides, it's not the `cc` in the Xcode toolchain that's wrong, it's the `/usr/bin/cc` behaviour that is a bit too magical.
- Invoke `xcrun --sdk macosx cc`.
- This completely ignores `SDKROOT`, so we'd still have to parse that first to figure out if it's suitable or not, but would probably be workable.
- Maybe somehow configure the linker with extra flags such that it'll be able to link regardless of linking for macOS or e.g. iOS? Though I doubt this is possible.
- Bundle the SDK, similar to `zig-cc`.
- Comes with it's own host of problems.
### Testing
Tested that this works with the following `-Clinker=...`:
- [x] Default (`cc`)
- [x] `/usr/bin/ld`
- [x] Actual Clang from Xcode (`/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang`)
- [x] `/usr/bin/clang` (invoked via `clang` instead of `cc`)
- [x] Homebrew's `llvm` package (ignores `SDKROOT`, uses their own SDK)
- [x] Homebrew's `gcc` package (`SDKROOT` is preferred over their own SDK)
- [x] ~Macports `clang`~ Couldn't get it to build
- [x] Macports `gcc` (`SDKROOT` is preferred over their own SDK)
- [x] Zig CC installed via. homebrew (ignores both `-isysroot` and `SDKROOT`, uses their own SDK)
- [x] Nixpkgs `clang` (ignores `SDKROOT`, uses their own SDK)
- [x] Nixpkgs `gcc` (ignores `SDKROOT`, uses their own SDK)
- [x] ~[`cosmocc`](https://github.com/jart/cosmopolitan)?~ Doesn't accept common flags (like `-arch`)
CC ```````@BlackHoleFox``````` ```````@thomcc```````
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LLVM removed the size parameter from the lifetime format.
Tolerate not having that size parameter.
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This is a technically a breaking change for what can be parsed in
`#[cfg(false)]`.
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The exact reasoning why we do not always pass the SDK root when linking
on macOS eludes me, but I suspect it's because we want to support
compiler drivers which do not support the `-isysroot` option.
Since we now pass the SDK root via the environment variable SDKROOT,
compiler drivers that don't support it can just ignore it.
Similarly, since we only warn when xcrun fails, users that expect their
compiler driver to provide the SDK location can do so now.
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Rollup of 4 pull requests
Successful merges:
- rust-lang/rust#144966 ( Improve suggestion for "missing function argument" on multiline call)
- rust-lang/rust#145111 (remove some unused private trait impls)
- rust-lang/rust#145221 (Fix Cargo cross-compilation (take two))
- rust-lang/rust#145247 (Update `sysinfo` version to `0.37.0`)
r? `@ghost`
`@rustbot` modify labels: rollup
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Ship correct Cranelift library in its dist component
The first commit adds a post-dist UI test to check that Cranelift can be used with the extracted dist x64 Linux archive.
The original codegen copy logic in the Cranelift dist step was a bit redundant, and I didn't notice in https://github.com/rust-lang/rust/pull/144787 that it's copying the codegen backend from the build compiler's sysroot, rather than the target compiler's sysroot. The second commit modifies the logic to directly access the built codegen file (there is no need to search for it in the compiler's sysroot, in fact when you run just `x dist rustc_codegen_cranelift`, it shouldn't "taint" the sysroot with the codegen backend! Which it did before https://github.com/rust-lang/rust/pull/144787) and copy it to the tarball under a normalized name. Thus we get around any similar potential issues in the future, and make previously implicit logic more explicit.
This also fixes running just `x dist rustc_codegen_cranelift` without enabling `cranelift` in `rust.codegen-backends`, which should have been enabled by https://github.com/rust-lang/rust/pull/144787, but it didn't work fully, because the dist step tried to copy the codegen backend from the compiler's sysroot, but it didn't contain the codegen backend if it was not enabled by `rust.codegen-backends`.
Fixes: https://github.com/rust-lang/rust/issues/145201
try-job: dist-x86_64-linux
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`NamedValueStr`
Modify `AttributeTemplate` to support list of alternatives for list and name value attribute styles.
Suggestions now provide more correct suggested code:
```
error[E0805]: malformed `used` attribute input
--> $DIR/used_with_multi_args.rs:3:1
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LL | #[used(compiler, linker)]
| ^^^^^^------------------^
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| expected a single argument here
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help: try changing it to one of the following valid forms of the attribute
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LL - #[used(compiler, linker)]
LL + #[used(compiler)]
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LL - #[used(compiler, linker)]
LL + #[used(linker)]
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LL - #[used(compiler, linker)]
LL + #[used]
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```
instead of the prior "masking" of the lack of this feature by suggesting pipe-separated lists:
```
error[E0805]: malformed `used` attribute input
--> $DIR/used_with_multi_args.rs:3:1
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LL | #[used(compiler, linker)]
| ^^^^^^------------------^
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| expected a single argument here
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help: try changing it to one of the following valid forms of the attribute
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LL - #[used(compiler, linker)]
LL + #[used(compiler|linker)]
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LL - #[used(compiler, linker)]
LL + #[used]
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```
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Improve suggestion for "missing function argument" on multiline call
`rustc` has a very neat suggestion when the argument count does not match, with a nice placeholder that shows where an argument may be missing. Unfortunately the suggestion is always single-line, even when the function call spans across multiple lines. With this PR, `rustc` tries to guess if the function call is multiline or not, and emits a multiline suggestion when required.
r? `@jdonszelmann`
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Set the dead_on_return attribute (added in LLVM 21) for arguments
that are passed indirectly, but not byval.
This indicates that the value of the argument on return does not
matter, enabling additional dead store elimination.
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Fix macro infinite recursion test to not trigger warning about semicolon in expr
The test cases for rust-lang/rust#41731 are about infinite macro recursion that
incorporates `print!` and `println!`. However, they also included
trailing semicolons despite expanding to expressions; that isn't what
these particular test cases are designed to test.
Eliminate the trailing semicolons, to simplify future work on removing
this special case. Every *other* macro that expands to a semicolon in an
expression is a test case for that specifically.
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Ignore coroutine witness type region args in auto trait confirmation
## The problem
Consider code like:
```
async fn process<'a>() {
Box::pin(process()).await;
}
fn require_send(_: impl Send) {}
fn main() {
require_send(process());
}
```
When proving that the coroutine `{coroutine@process}::<'?0>: Send`, we end up instantiating a nested goal `{witness@process}::<'?0>: Send` by synthesizing a witness type from the coroutine's args:
Proving a coroutine witness type implements an auto trait requires looking up the coroutine's witness types. The witness types are a binder that look like `for<'r> { Pin<Box<{coroutine@process}::<'r>>> }`. We instantiate this binder with placeholders and prove `Send` on the witness types. This ends up eventually needing to prove something like `{coroutine@process}::<'!1>: Send`. Repeat this process, and we end up in an overflow during fulfillment, since fulfillment does not use freshening.
This can be visualized with a trait stack that ends up looking like:
* `{coroutine@process}::<'?0>: Send`
* `{witness@process}::<'?0>: Send`
* `Pin<Box<{coroutine@process}::<'!1>>>: Send`
* `{coroutine@process}::<'!1>: Send`
* ...
* `{coroutine@process}::<'!2>: Send`
* `{witness@process}::<'!2>: Send`
* ...
* overflow!
The problem here specifically comes from the first step: synthesizing a witness type from the coroutine's args.
## Why wasn't this an issue before?
Specifically, before 63f6845e570305a92eaf855897768617366164d6, this wasn't an issue because we were instead extracting the witness from the coroutine type itself. It turns out that given some `{coroutine@process}::<'?0>`, the witness type was actually something like `{witness@process}::<'erased>`!
So why do we end up with a witness type with `'erased` in its args? This is due to the fact that opaque type inference erases all regions from the witness. This is actually explicitly part of opaque type inference -- changing this to actually visit the witness types actually replicates this overflow even with 63f6845e570305a92eaf855897768617366164d6 reverted:
https://github.com/rust-lang/rust/blob/ca77504943887037504c7fc0b9bf06dab3910373/compiler/rustc_borrowck/src/type_check/opaque_types.rs#L303-L313
To better understand this difference and how it avoids a cycle, if you look at the trait stack before 63f6845e570305a92eaf855897768617366164d6, we end up with something like:
* `{coroutine@process}::<'?0>: Send`
* `{witness@process}::<'erased>: Send` **<-- THIS CHANGED**
* `Pin<Box<{coroutine@process}::<'!1>>>: Send`
* `{coroutine@process}::<'!1>: Send`
* ...
* `{coroutine@process}::<'erased>: Send` **<-- THIS CHANGED**
* `{witness@process}::<'erased>: Send` **<-- THIS CHANGED**
* coinductive cycle! :tada:
## So what's the fix?
This hack replicates the behavior in opaque type inference to erase regions from the witness type, but instead erasing the regions during auto trait confirmation. This is kinda a hack, but is sound. It does not need to be replicated in the new trait solver, of course.
---
I hope this explanation makes sense.
We could beta backport this instead of the revert https://github.com/rust-lang/rust/pull/145193, but then I'd like to un-revert that on master in this PR along with landing this this hack. Thoughts?
r? lcnr
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Check coroutine upvars in dtorck constraint
Fix rust-lang/rust#144155.
This PR fixes an unsoundness where we were not considering coroutine upvars as drop-live if the coroutine interior types (witness types) had nothing which required drop.
In the case that the coroutine does not have any interior types that need to be dropped, then we don't need to treat all of the upvars as use-live; instead, this PR uses the same logic as closures, and descends into the upvar types to collect anything that must be drop-live. The rest of this PR is reworking the comment to explain the behavior here.
r? `@lcnr` or reassign 😸
---
Just some thoughts --- a proper fix for this whole situation would be to consider `TypingMode` in the `needs_drop` function, and just calling `coroutine_ty.needs_drop(tcx, typing_env)` in the dtorck constraint check.
During MIR building, we should probably use a typing mode that stalls the local coroutines and considers them to be unconditionally drop, or perhaps just stall *all* coroutines in analysis mode. Then in borrowck mode, we can re-check `needs_drop` but descend into witness types properly. https://github.com/rust-lang/rust/pull/144158 implements this experimentally.
This is a pretty involved fix, and conflicts with some in-flight changes (rust-lang/rust#144157) that I have around removing coroutine witnesses altogether. I'm happy to add a FIXME to rework this whole approach, but I don't want to block this quick fix since it's obviously more correct than the status-quo.
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Reject relaxed bounds inside associated type bounds (ATB)
**Reject** relaxed bounds — most notably `?Sized` — inside associated type bounds `TraitRef<AssocTy: …>`.
This was previously accepted without warning despite being incorrect: ATBs are *not* a place where we perform *sized elaboration*, meaning `TraitRef<AssocTy: …>` does *not* elaborate to `TraitRef<AssocTy: Sized + …>` if `…` doesn't contain `?Sized`. Therefore `?Sized` is meaningless. In no other (stable) place do we (intentionally) allow relaxed bounds where we don't also perform sized elab, this is highly inconsistent and confusing! Another point of comparison: For the desugared `$SelfTy: TraitRef, $SelfTy::AssocTy: …` we don't do sized elab either (and thus also don't allow relaxed bounds).
Moreover — as I've alluded to back in https://github.com/rust-lang/rust/pull/135841#pullrequestreview-2619462717 — some later validation steps only happen during sized elaboration during HIR ty lowering[^1]. Namely, rejecting duplicates (e.g., `?Trait + ?Trait`) and ensuring that `Trait` in `?Trait` is equal to `Sized`[^2]. As you can probably guess, on stable/master we don't run these checks for ATBs (so we allow even more nonsensical bounds like `Iterator<Item: ?Copy>` despite T-types's ruling established in the FCP'ed rust-lang/rust#135841).
This PR rectifies all of this. I cratered this back in 2025-01-10 with (allegedly) no regressions found ([report](https://github.com/rust-lang/rust/pull/135331#issuecomment-2585330783), [its analysis](https://github.com/rust-lang/rust/pull/135331#issuecomment-2585356422)). [However a contributor manually found two occurrences](https://github.com/rust-lang/rust/issues/135229#issuecomment-2581832852) of `TraitRef<AssocTy: ?Sized>` in small hobby projects (presumably via GH code search). I immediately sent downstream PRs: https://github.com/Gui-Yom/turbo-metrics/pull/14, https://github.com/ireina7/summon/pull/1 (however, the owners have showed no reaction so far).
I'm leaning towards banning these forms **without a FCW** because a FCW isn't worth the maintenance cost[^3]. Note that associated type bounds were stabilized in 1.79.0 (released 2024-06-13 which is 13 months ago), so the proliferation of ATBs shouldn't be that high yet. If you think we should do another crater run since the last one was 6 months ago, I'm fine with that.
Fixes rust-lang/rust#135229.
[^1]: I consider this a flaw in the implementation and [I've already added a huge FIXME](https://github.com/rust-lang/rust/blob/82a02aefe07092c737c852daccebf49ca25507e3/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs#L195-L207).
[^2]: To be more precise, if the internal flag `-Zexperimental-default-bounds` is provided other "default traits" (needs internal feature `lang_items`) are permitted as well (cc closely related internal feature: `more_maybe_bounds`).
[^3]: Having to track this and adding an entire lint whose remnants would remain in the code base forever (we never *fully* remove lints).
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Rollup of 7 pull requests
Successful merges:
- rust-lang/rust#143949 (Constify remaining traits/impls for `const_ops`)
- rust-lang/rust#144330 (document assumptions about `Clone` and `Eq` traits)
- rust-lang/rust#144350 (std: sys: io: io_slice: Add UEFI types)
- rust-lang/rust#144558 (Point at the `Fn()` or `FnMut()` bound that coerced a closure, which caused a move error)
- rust-lang/rust#145149 (Make config method invoke inside parse use dwn_ctx)
- rust-lang/rust#145227 (Tweak spans providing type context on errors when involving macros)
- rust-lang/rust#145228 (Remove unnecessary parentheses in `assert!`s)
r? `@ghost`
`@rustbot` modify labels: rollup
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Tweak spans providing type context on errors when involving macros
Do not point at macro invocation multiple times when we try to add span labels mentioning what type each expression has, which is unnecessary when the error is at a macro invocation.
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Point at the `Fn()` or `FnMut()` bound that coerced a closure, which caused a move error
When encountering a move error involving a closure because the captured value isn't `Copy`, and the obligation comes from a bound on a type parameter that requires `Fn` or `FnMut`, we point at it and explain that an `FnOnce` wouldn't cause the move error.
```
error[E0507]: cannot move out of `foo`, a captured variable in an `Fn` closure
--> f111.rs:15:25
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14 | fn do_stuff(foo: Option<Foo>) {
| --- ----------- move occurs because `foo` has type `Option<Foo>`, which does not implement the `Copy` trait
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| captured outer variable
15 | require_fn_trait(|| async {
| -- ^^^^^ `foo` is moved here
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| captured by this `Fn` closure
16 | if foo.map_or(false, |f| f.foo()) {
| --- variable moved due to use in coroutine
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help: `Fn` and `FnMut` closures require captured values to be able to be consumed multiple times, but an `FnOnce` consume them only once
--> f111.rs:12:53
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12 | fn require_fn_trait<F: Future<Output = ()>>(_: impl Fn() -> F) {}
| ^^^^^^^^^
help: consider cloning the value if the performance cost is acceptable
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16 | if foo.clone().map_or(false, |f| f.foo()) {
| ++++++++
```
Fix rust-lang/rust#68119, by pointing at `Fn` and `FnMut` bounds involved in move errors.
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