Reject generic self types.
The RFC for arbitrary self types v2 declares that we should reject "generic" self types. This commit does so.
The definition of "generic" was unclear in the RFC, but has been explored in
https://github.com/rust-lang/rust/issues/129147
and the conclusion is that "generic" means any `self` type which is a type parameter defined on the method itself, or references to such a type.
This approach was chosen because other definitions of "generic" don't work. Specifically,
* we can't filter out generic type _arguments_, because that would filter out Rc<Self> and all the other types of smart pointer we want to support;
* we can't filter out all type params, because Self itself is a type param, and because existing Rust code depends on other type params declared on the type (as opposed to the method).
This PR decides to make a new error code for this case, instead of reusing the existing E0307 error. This makes the code a bit more complex, but it seems we have an opportunity to provide specific diagnostics for this case so we should do so.
This PR filters out generic self types whether or not the 'arbitrary self types' feature is enabled. However, it's believed that it can't have any effect on code which uses stable Rust, since there are no stable traits which can be used to indicate a valid generic receiver type, and thus it would have been impossible to write code which could trigger this new error case. It is however possible that this could break existing code which uses either of the unstable `arbitrary_self_types` or `receiver_trait` features. This breakage is intentional; as we move arbitrary self types towards stabilization we don't want to continue to support generic such types.
This PR adds lots of extra tests to arbitrary-self-from-method-substs. Most of these are ways to trigger a "type mismatch" error which 9b82580c73/compiler/rustc_hir_typeck/src/method/confirm.rs (L519) hopes can be minimized by filtering out generics in this way. We remove a FIXME from confirm.rs suggesting that we make this change. It's still possible to cause type mismatch errors, and a subsequent PR may be able to improve diagnostics in this area, but it's harder to cause these errors without contrived uses of the turbofish.
This is a part of the arbitrary self types v2 project, https://github.com/rust-lang/rfcs/pull/3519https://github.com/rust-lang/rust/issues/44874
r? `@wesleywiser`
The RFC for arbitrary self types v2 declares that we should reject
"generic" self types. This commit does so.
The definition of "generic" was unclear in the RFC, but has been
explored in
https://github.com/rust-lang/rust/issues/129147
and the conclusion is that "generic" means any `self` type which
is a type parameter defined on the method itself, or references
to such a type.
This approach was chosen because other definitions of "generic"
don't work. Specifically,
* we can't filter out generic type _arguments_, because that would
filter out Rc<Self> and all the other types of smart pointer
we want to support;
* we can't filter out all type params, because Self itself is a
type param, and because existing Rust code depends on other
type params declared on the type (as opposed to the method).
This PR decides to make a new error code for this case, instead of
reusing the existing E0307 error. This makes the code a
bit more complex, but it seems we have an opportunity to provide
specific diagnostics for this case so we should do so.
This PR filters out generic self types whether or not the
'arbitrary self types' feature is enabled. However, it's believed
that it can't have any effect on code which uses stable Rust, since
there are no stable traits which can be used to indicate a valid
generic receiver type, and thus it would have been impossible to
write code which could trigger this new error case.
It is however possible that this could break existing code which
uses either of the unstable `arbitrary_self_types` or
`receiver_trait` features. This breakage is intentional; as
we move arbitrary self types towards stabilization we don't want
to continue to support generic such types.
This PR adds lots of extra tests to arbitrary-self-from-method-substs.
Most of these are ways to trigger a "type mismatch" error which
9b82580c73/compiler/rustc_hir_typeck/src/method/confirm.rs (L519)
hopes can be minimized by filtering out generics in this way.
We remove a FIXME from confirm.rs suggesting that we make this change.
It's still possible to cause type mismatch errors, and a subsequent
PR may be able to improve diagnostics in this area, but it's harder
to cause these errors without contrived uses of the turbofish.
This is a part of the arbitrary self types v2 project,
https://github.com/rust-lang/rfcs/pull/3519https://github.com/rust-lang/rust/issues/44874
r? @wesleywiser
Fix directives for lint-non-snake-case-crate
This test fails on targets without unwinding or with `--target-rustcflags=-Cpanic=abort` because the proc macro was compiled as the target, not the host. Some targets were explicitly disabled to pass CI, but these directives are more general.
* `needs-dynamic-linking` is self explanatory
* `force-host` for proc macros
* `no-prefer-dynamic` is apparently also used for proc macros
Note that `needs-unwind` can also be useful for situations other than proc macros where unwinding is necessary.
r? `@jieyouxu`
try-job: test-various
Use `token_descr` more in error messages
This is the first two commits from #124141, put into their own PR to get things rolling. Commit messages have the details.
r? ``@estebank``
cc ``@petrochenkov``
Don't lint `irrefutable_let_patterns` on leading patterns if `else if` let-chains
fixes#128661
Is there any preference where the test goes? There looks to be several places it could fit.
This test fails on targets without unwinding because the proc macro was
compiled as the target, not the host. Some targets were explicitly
disabled to pass CI, but these directives are more general.
Fixes Fuchsia tests.
Remove detail from label/note that is already available in other note
Remove the "which is required by `{root_obligation}`" post-script in
"the trait `X` is not implemented for `Y`" explanation in E0277. This
information is already conveyed in the notes explaining requirements,
making it redundant while making the text (particularly in labels)
harder to read.
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
vs the prior
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`, which is required by `Option<NotCopy>: Copy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
*Ignore first three commits from https://github.com/rust-lang/rust/pull/132086.*
Ensure that resume arg outlives region bound for coroutines
When proving that `{Coroutine}: 'region`, we must also prove that the coroutine's resume ty outlives that region as well. See the inline comment.
Fixes#132104
Remove the "which is required by `{root_obligation}`" post-script in
"the trait `X` is not implemented for `Y`" explanation in E0277. This
information is already conveyed in the notes explaining requirements,
making it redundant while making the text (particularly in labels)
harder to read.
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
vs the prior
```
error[E0277]: the trait bound `NotCopy: Copy` is not satisfied
--> $DIR/wf-static-type.rs:10:13
|
LL | static FOO: IsCopy<Option<NotCopy>> = IsCopy { t: None };
| ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `NotCopy`, which is required by `Option<NotCopy>: Copy`
|
= note: required for `Option<NotCopy>` to implement `Copy`
note: required by a bound in `IsCopy`
--> $DIR/wf-static-type.rs:7:17
|
LL | struct IsCopy<T:Copy> { t: T }
| ^^^^ required by this bound in `IsCopy`
```
Collect item bounds for RPITITs from trait where clauses just like associated types
We collect item bounds from trait where clauses for *associated types*, i.e. this:
```rust
trait Foo
where
Self::Assoc: Send
{
type Assoc;
}
```
Becomes this:
```rust
trait Foo {
type Assoc: Send;
}
```
Today, with RPITITs/AFIT and return-type notation, we don't do that, i.e.:
```rust
trait Foo where Self::method(..): Send {
fn method() -> impl Sized;
}
fn is_send(_: impl Send) {}
fn test<T: Foo>() {
is_send(T::method());
}
```
...which fails on nightly today.
Turns out it's super easy to fix this, and we just need to use the `associated_type_bounds` lowering function in `explicit_item_bounds_with_filter`, which has that logic baked in.
Hack out effects support for old solver
Opening this for vibes ✨
Turns out that a basic, somewhat incomplete implementation of host effects is achievable in the old trait solver pretty easily. This should be sufficient for us to use in the standard library itself.
Regarding incompleteness, maybe we should always treat host predicates as ambiguous in intercrate mode (at least in the old solver) to avoid any worries about accidental impl overlap or something.
r? ```@lcnr``` cc ```@fee1-dead```
Lint against getting pointers from immediately dropped temporaries
Fixes#123613
## Changes:
1. New lint: `dangling_pointers_from_temporaries`. Is a generalization of `temporary_cstring_as_ptr` for more types and more ways to get a temporary.
2. `temporary_cstring_as_ptr` is removed and marked as renamed to `dangling_pointers_from_temporaries`.
3. `clippy::temporary_cstring_as_ptr` is marked as renamed to `dangling_pointers_from_temporaries`.
4. Fixed a false positive[^fp] for when the pointer is not actually dangling because of lifetime extension for function/method call arguments.
5. `core::cell::Cell` is now `rustc_diagnostic_item = "Cell"`
## Questions:
- [ ] Instead of manually checking for a list of known methods and diagnostic items, maybe add some sort of annotation to those methods in library and check for the presence of that annotation? https://github.com/rust-lang/rust/pull/128985#issuecomment-2318714312
## Known limitations:
### False negatives[^fn]:
See the comments in `compiler/rustc_lint/src/dangling.rs`
1. Method calls that are not checked for:
- `temporary_unsafe_cell.get()`
- `temporary_sync_unsafe_cell.get()`
2. Ways to get a temporary that are not recognized:
- `owning_temporary.field`
- `owning_temporary[index]`
3. No checks for ref-to-ptr conversions:
- `&raw [mut] temporary`
- `&temporary as *(const|mut) _`
- `ptr::from_ref(&temporary)` and friends
[^fn]: lint **should** be emitted, but **is not**
[^fp]: lint **should not** be emitted, but **is**
Lower AST node id only once
Fixes#96346.
I basically followed the given instructions except the inline part.
`lower_jump_destination` can't reuse local existing `HirId` due to unknown name resolution result so I created an additional mapping for labels.
r? ```@cjgillot```
Rollup of 4 pull requests
Successful merges:
- #131391 (Stabilize `isqrt` feature)
- #132248 (rustc_transmute: Directly use types from rustc_abi)
- #132252 (compiler: rename LayoutS to LayoutData)
- #132253 (Known-bug test for `keyword_idents` lint not propagating to other files)
r? `@ghost`
`@rustbot` modify labels: rollup
Known-bug test for `keyword_idents` lint not propagating to other files
Known-bug test for `keyword_idents` lint not propagating to other files when configured via attribute (#132218).
fix various linker warnings
separated out from https://github.com/rust-lang/rust/pull/119286; this doesn't have anything user-facing, i just want to land these changes so i can stop rebasing them.
r? `@bjorn3`
Remove `ObligationCause::span()` method
I think it's an incredibly confusing footgun to expose both `obligation_cause.span` and `obligation_cause.span()`. Especially because `ObligationCause::span()` (the method) seems to just be hacking around a single quirk in the way we set up obligation causes for match arms.
First commit removes the need for that hack, with only one diagnostic span changing (but IMO not really getting worse -- I'd argue that it was already confusing).
Much like the previous commit.
I think the removal of "the token" in each message is fine here. There
are many more error messages that mention tokens without saying "the
token" than those that do say it.
By using `token_descr`, as is done for many other errors, we can get
slightly better descriptions in error messages, e.g.
"macro expansion ignores token `let` and any following" becomes
"macro expansion ignores keyword `let` and any tokens following".
This will be more important once invisible delimiters start being
mentioned in error messages -- without this commit, that leads to error
messages such as "error at ``" because invisible delimiters are
pretty printed as an empty string.
this makes it much easier to understand test failures.
before:
```
diff of stderr:
1 error: linking with `LINKER` failed: exit status: 1
2 |
- ld: Undefined symbols:
4 _CFRunLoopGetTypeID, referenced from:
5 clang: error: linker command failed with exit code 1 (use -v to see invocation)
```
after:
```
=== HAYSTACK ===
error: linking with `cc` failed: exit status: 1
|
= note: use `--verbose` to show all linker arguments
= note: Undefined symbols for architecture arm64:
"_CFRunLoopGetTypeID", referenced from:
main::main::hbb553f5dda62d3ea in main.main.d17f5fbe6225cf88-cgu.0.rcgu.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: aborting due to 1 previous error
=== NEEDLE ===
_CFRunLoopGetTypeID\.?, referenced from:
thread 'main' panicked at /Users/jyn/git/rust-lang/rust/tests/run-make/linkage-attr-framework/rmake.rs:22:10:
needle was not found in haystack
```
this also fixes a failure related to missing whitespace; we don't actually care about whitespace in this test.
Cleanup: Move an impl-Trait check from AST validation to AST lowering
Namely the one that rejects `impl Trait` in qself types and non-final path segments.
There's no good reason to perform this during AST validation.
We have better infrastructure in place in the AST lowerer (`ImplTraitContext`).
This shaves off a lot of code.
We now lower `impl Trait` in bad positions to `{type error}` which allows us to
remove a special case from HIR ty lowering.
Coincidentally fixes#126725. Well, it only *masks* it by passing `{type error}` to HIR analysis instead of a "bad" opaque. I was able to find a new reproducer for it. See the issue.
Rename macro `SmartPointer` to `CoercePointee`
As per resolution #129104 we will rename the macro to better reflect the technical specification of the feature and clarify the communication.
- `SmartPointer` is renamed to `CoerceReferent`
- `#[pointee]` attribute is renamed to `#[referent]`
- `#![feature(derive_smart_pointer)]` gate is renamed to `#![feature(derive_coerce_referent)]`.
- Any mention of `SmartPointer` in the file names are renamed accordingly.
r? `@compiler-errors`
cc `@nikomatsakis` `@Darksonn`
rustc_target: Add pauth-lr aarch64 target feature
Add the pauth-lr target feature, corresponding to aarch64 FEAT_PAuth_LR. This feature has been added in LLVM 19.
It is currently not supported by the Linux hwcap and so we cannot add runtime feature detection for it at this time.
r? `@Amanieu`
Deny calls to non-`#[const_trait]` methods in MIR constck
This is a (potentially temporary) fix that closes off the mismatch in assumptions between MIR constck and typeck which does the const traits checking. Before this PR, MIR constck assumed that typeck correctly handled all calls to trait methods in const contexts if effects is enabled. That is not true because typeck only correctly handles callees that are const. For non-const callees (such as methods in a non-const_trait), typeck had never created an error.
45089ec19e/compiler/rustc_hir_typeck/src/callee.rs (L876-L877)
I called this potentially temporary because the const checks could be moved to HIR entirely. Alongside the recent refactor in const stability checks where that component could be placed would need more discussion. (cc ```@compiler-errors``` ```@RalfJung)```
Tests are updated, mainly due to traits not being const in core, so tests that call them correctly error.
This fixes https://github.com/rust-lang/project-const-traits/issues/12.
Const stability checks v2
The const stability system has served us well ever since `const fn` were first stabilized. It's main feature is that it enforces *recursive* validity -- a stable const fn cannot internally make use of unstable const features without an explicit marker in the form of `#[rustc_allow_const_fn_unstable]`. This is done to make sure that we don't accidentally expose unstable const features on stable in a way that would be hard to take back. As part of this, it is enforced that a `#[rustc_const_stable]` can only call `#[rustc_const_stable]` functions. However, some problems have been coming up with increased usage:
- It is baffling that we have to mark private or even unstable functions as `#[rustc_const_stable]` when they are used as helpers in regular stable `const fn`, and often people will rather add `#[rustc_allow_const_fn_unstable]` instead which was not our intention.
- The system has several gaping holes: a private `const fn` without stability attributes whose inherited stability (walking up parent modules) is `#[stable]` is allowed to call *arbitrary* unstable const operations, but can itself be called from stable `const fn`. Similarly, `#[allow_internal_unstable]` on a macro completely bypasses the recursive nature of the check.
Fundamentally, the problem is that we have *three* disjoint categories of functions, and not enough attributes to distinguish them:
1. const-stable functions
2. private/unstable functions that are meant to be callable from const-stable functions
3. functions that can make use of unstable const features
Functions in the first two categories cannot use unstable const features and they can only call functions from the first two categories.
This PR implements the following system:
- `#[rustc_const_stable]` puts functions in the first category. It may only be applied to `#[stable]` functions.
- `#[rustc_const_unstable]` by default puts functions in the third category. The new attribute `#[rustc_const_stable_indirect]` can be added to such a function to move it into the second category.
- `const fn` without a const stability marker are in the second category if they are still unstable. They automatically inherit the feature gate for regular calls, it can now also be used for const-calls.
Also, all the holes mentioned above have been closed. There's still one potential hole that is hard to avoid, which is when MIR building automatically inserts calls to a particular function in stable functions -- which happens in the panic machinery. Those need to be manually marked `#[rustc_const_stable_indirect]` to be sure they follow recursive const stability. But that's a fairly rare and special case so IMO it's fine.
The net effect of this is that a `#[unstable]` or unmarked function can be constified simply by marking it as `const fn`, and it will then be const-callable from stable `const fn` and subject to recursive const stability requirements. If it is publicly reachable (which implies it cannot be unmarked), it will be const-unstable under the same feature gate. Only if the function ever becomes `#[stable]` does it need a `#[rustc_const_unstable]` or `#[rustc_const_stable]` marker to decide if this should also imply const-stability.
Adding `#[rustc_const_unstable]` is only needed for (a) functions that need to use unstable const lang features (including intrinsics), or (b) `#[stable]` functions that are not yet intended to be const-stable. Adding `#[rustc_const_stable]` is only needed for functions that are actually meant to be directly callable from stable const code. `#[rustc_const_stable_indirect]` is used to mark intrinsics as const-callable and for `#[rustc_const_unstable]` functions that are actually called from other, exposed-on-stable `const fn`. No other attributes are required.
Also see the updated dev-guide at https://github.com/rust-lang/rustc-dev-guide/pull/2098.
I think in the future we may want to tweak this further, so that in the hopefully common case where a public function's const-stability just exactly mirrors its regular stability, we never have to add any attribute. But right now, once the function is stable this requires `#[rustc_const_stable]`.
### Open question
There is one point I could see we might want to do differently, and that is putting `#[rustc_const_unstable]` functions (but not intrinsics) in category 2 by default, and requiring an extra attribute for `#[rustc_const_not_exposed_on_stable]` or so. This would require a bunch of extra annotations, but would have the advantage that turning a `#[rustc_const_unstable]` into `#[rustc_const_stable]` will never change the way the function is const-checked. Currently, we often discover in the const stabilization PR that a function needs some other unstable const things, and then we rush to quickly deal with that. In this alternative universe, we'd work towards getting rid of the `rustc_const_not_exposed_on_stable` before stabilization, and once that is done stabilization becomes a trivial matter. `#[rustc_const_stable_indirect]` would then only be used for intrinsics.
I think I like this idea, but might want to do it in a follow-up PR, as it will need a whole bunch of annotations in the standard library. Also, we probably want to convert all const intrinsics to the "new" form (`#[rustc_intrinsic]` instead of an `extern` block) before doing this to avoid having to deal with two different ways of declaring intrinsics.
Cc `@rust-lang/wg-const-eval` `@rust-lang/libs-api`
Part of https://github.com/rust-lang/rust/issues/129815 (but not finished since this is not yet sufficient to safely let us expose `const fn` from hashbrown)
Fixes https://github.com/rust-lang/rust/issues/131073 by making it so that const-stable functions are always stable
try-job: test-various
