lint/ctypes: fix `()` return type checks
Fixes#113436.
`()` is normally FFI-unsafe, but is FFI-safe when used as a return type. It is also desirable that a transparent newtype for `()` is FFI-safe when used as a return type.
In order to support this, when a type was deemed FFI-unsafe, because of a `()` type, and was used in return type - then the type was considered FFI-safe. However, this was the wrong approach - it didn't check that the `()` was part of a transparent newtype! The consequence of this is that the presence of a `()` type in a more complex return type would make it the entire type be considered safe (as long as the `()` type was the first that the lint found) - which is obviously incorrect.
Instead, this logic is removed, and after [consultation with t-lang](https://github.com/rust-lang/rust/issues/113436#issuecomment-1640756721), I've fixed the bugs and inconsistencies and made `()` FFI-safe within types.
I also refactor a function, but that's not too exciting.
Now that this lint runs on any external-ABI fn-ptr, normalization won't
always succeed, so use `try_normalize_erasing_regions` instead.
Signed-off-by: David Wood <david@davidtw.co>
Consider `()` within types to be FFI-safe, and `()` to be FFI-safe as a
return type (incl. when in a transparent newtype).
Signed-off-by: David Wood <david@davidtw.co>
`()` is normally FFI-unsafe, but is FFI-safe when used as a return type.
It is also desirable that a transparent newtype for `()` is FFI-safe when
used as a return type.
In order to support this, when an type was deemed FFI-unsafe, because of
a `()` type, and was used in return type - then the type was considered
FFI-safe. However, this was the wrong approach - it didn't check that the
`()` was part of a transparent newtype! The consequence of this is that
the presence of a `()` type in a more complex return type would make it
the entire type be considered safe (as long as the `()` type was the
first that the lint found) - which is obviously incorrect.
Instead, this logic is removed, and a unit return type or a transparent
wrapper around a unit is checked for directly for functions and fn-ptrs.
Signed-off-by: David Wood <david@davidtw.co>
Fix removal span calculation of `unused_qualifications` suggestion
Given a path such as `std::ops::Index<str>`, calculate the unnecessary qualification removal span by computing the beginning of the entire span until the ident span of the last path segment, which handles generic arguments and lifetime arguments in the last path segment. Previous logic only kept the ident span of the last path segment which is incorrect.
Closes#113808.
Uplift `clippy::fn_null_check` lint
This PR aims at uplifting the `clippy::fn_null_check` lint into rustc.
## `incorrect_fn_null_checks`
(warn-by-default)
The `incorrect_fn_null_checks` lint checks for expression that checks if a function pointer is null.
### Example
```rust
let fn_ptr: fn() = /* somehow obtained nullable function pointer */
if (fn_ptr as *const ()).is_null() { /* ... */ }
```
### Explanation
Function pointers are assumed to be non-null, checking for their nullity is incorrect.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
Remove chalk support from the compiler
Removes chalk (`-Ztrait-solver=chalk`) from the compiler and prunes any dead code resulting from this, mainly:
* Remove the chalk compatibility layer in `compiler/rustc_traits/src/chalk`
* Remove the chalk flag `-Ztrait-solver=chalk` and its `TraitEngine` implementation
* Remove `TypeWellFormedFromEnv` (and its many `bug!()` match arms)
* Remove the chalk migration mode from compiletest
* Remove the `chalkify` UI tests (do we want to keep any of these, but migrate them to `-Ztrait-solver=next`??)
Fulfills rust-lang/types-team#93.
r? `@jackh726`
Extend previous checks for external ABI fn-ptrs to use in internal
statics, constants, type aliases and algebraic data types.
Signed-off-by: David Wood <david.wood@huawei.com>
Extend previous commit's support for checking for external fn-ptrs in
internal fn types to report errors for multiple found fn-ptrs.
Signed-off-by: David Wood <david.wood@huawei.com>
Instead of skipping functions with internal ABIs, check that the
signature doesn't contain any fn-ptr types with external ABIs that
aren't FFI-safe.
Signed-off-by: David Wood <david.wood@huawei.com>
Extend `unused_must_use` to cover block exprs
Given code like
```rust
#[must_use]
fn foo() -> i32 {
42
}
fn warns() {
{
foo();
}
}
fn does_not_warn() {
{
foo()
};
}
fn main() {
warns();
does_not_warn();
}
```
### Before This PR
```
warning: unused return value of `foo` that must be used
--> test.rs:8:9
|
8 | foo();
| ^^^^^
|
= note: `#[warn(unused_must_use)]` on by default
help: use `let _ = ...` to ignore the resulting value
|
8 | let _ = foo();
| +++++++
warning: 1 warning emitted
```
### After This PR
```
warning: unused return value of `foo` that must be used
--> test.rs:8:9
|
8 | foo();
| ^^^^^
|
= note: `#[warn(unused_must_use)]` on by default
help: use `let _ = ...` to ignore the resulting value
|
8 | let _ = foo();
| +++++++
warning: unused return value of `foo` that must be used
--> test.rs:14:9
|
14 | foo()
| ^^^^^
|
help: use `let _ = ...` to ignore the resulting value
|
14 | let _ = foo();
| +++++++ +
warning: 2 warnings emitted
```
Fixes#104253.
This commit reverts a change made in #111425.
It was believed that this change was necessary for implementing type privacy lints, but #111801 showed that it was not necessary.
Quite opposite, the revert fixes some issues.
This is apparently where it's busting stack, and the comments for `ensure_sufficient_stack` say that
> E.g. almost any call to visit_expr or equivalent can benefit from this.
Uplift `clippy::cmp_nan` lint
This PR aims at uplifting the `clippy::cmp_nan` lint into rustc.
## `invalid_nan_comparisons`
~~(deny-by-default)~~ (warn-by-default)
The `invalid_nan_comparisons` lint checks comparison with `f32::NAN` or `f64::NAN` as one of the operand.
### Example
```rust,compile_fail
let a = 2.3f32;
if a == f32::NAN {}
```
### Explanation
NaN does not compare meaningfully to anything – not even itself – so those comparisons are always false.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
Rollup of 3 pull requests
Successful merges:
- #112260 (Improve document of `unsafe_code` lint)
- #112429 ([rustdoc] List matching impls on type aliases)
- #112442 (Deduplicate identical region constraints in new solver)
r? `@ghost`
`@rustbot` modify labels: rollup
Uplift `clippy::undropped_manually_drops` lint
This PR aims at uplifting the `clippy::undropped_manually_drops` lint.
## `undropped_manually_drops`
(warn-by-default)
The `undropped_manually_drops` lint check for calls to `std::mem::drop` with a value of `std::mem::ManuallyDrop` which doesn't drop.
### Example
```rust
struct S;
drop(std::mem::ManuallyDrop::new(S));
```
### Explanation
`ManuallyDrop` does not drop it's inner value so calling `std::mem::drop` will not drop the inner value of the `ManuallyDrop` either.
-----
Mostly followed the instructions for uplifting an clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::undropped_manually_drops` into rustc
Extra context for unreachable_pub lint
While experienced Rustaceans no doubt know this sort of thing already, as more of a newbie I had trouble understanding why I was triggering the lint. Hopefully this expanded explanation saves someone else some head-scratching.
Fixes#110922
Uplift `clippy::invalid_utf8_in_unchecked` lint
This PR aims at uplifting the `clippy::invalid_utf8_in_unchecked` lint into two lints.
## `invalid_from_utf8_unchecked`
(deny-by-default)
The `invalid_from_utf8_unchecked` lint checks for calls to `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut` with an invalid UTF-8 literal.
### Example
```rust
unsafe {
std::str::from_utf8_unchecked(b"cl\x82ippy");
}
```
### Explanation
Creating such a `str` would result in undefined behavior as per documentation for `std::str::from_utf8_unchecked` and `std::str::from_utf8_unchecked_mut`.
## `invalid_from_utf8`
(warn-by-default)
The `invalid_from_utf8` lint checks for calls to `std::str::from_utf8` and `std::str::from_utf8_mut` with an invalid UTF-8 literal.
### Example
```rust
std::str::from_utf8(b"ru\x82st");
```
### Explanation
Trying to create such a `str` would always return an error as per documentation for `std::str::from_utf8` and `std::str::from_utf8_mut`.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
````@rustbot```` label: +I-lang-nominated
r? compiler
-----
For Clippy:
changelog: Moves: Uplifted `clippy::invalid_utf8_in_unchecked` into rustc
Each of `{D,Subd}iagnosticMessage::{Str,Eager}` has a comment:
```
// FIXME(davidtwco): can a `Cow<'static, str>` be used here?
```
This commit answers that question in the affirmative. It's not the most
compelling change ever, but it might be worth merging.
This requires changing the `impl<'a> From<&'a str>` impls to `impl
From<&'static str>`, which involves a bunch of knock-on changes that
require/result in call sites being a little more precise about exactly
what kind of string they use to create errors, and not just `&str`. This
will result in fewer unnecessary allocations, though this will not have
any notable perf effects given that these are error paths.
Note that I was lazy within Clippy, using `to_string` in a few places to
preserve the existing string imprecision. I could have used `impl
Into<{D,Subd}iagnosticMessage>` in various places as is done in the
compiler, but that would have required changes to *many* call sites
(mostly changing `&format("...")` to `format!("...")`) which didn't seem
worthwhile.
Add warn-by-default lint when local binding shadows exported glob re-export item
This PR introduces a warn-by-default rustc lint for when a local binding (a use statement, or a type declaration) produces a name which shadows an exported glob re-export item, causing the name from the exported glob re-export to be hidden (see #111336).
### Unresolved Questions
- [x] ~~Is this approach correct? While it passes the UI tests, I'm not entirely convinced it is correct.~~ Seems to be ok now.
- [x] ~~What should the lint be called / how should it be worded? I don't like calling `use x::*;` or `struct Foo;` a "local binding" but they are `NameBinding`s internally if I'm not mistaken.~~ ~~The lint is called `local_binding_shadows_glob_reexport` for now, unless a better name is suggested.~~ `hidden_glob_reexports`.
Fixes#111336.
Consider lint check attributes on match arms
Currently, lint check attributes on match arms have no effect for some lints. This PR makes some lint passes to take those attributes into account.
- `LateContextAndPass` for late lint doesn't update `last_node_with_lint_attrs` when it visits match arms. This leads to lint check attributes on match arms taking no effects on late lints that operate on the arms' pattern:
```rust
match value {
#[deny(non_snake_case)]
PAT => {} // `non_snake_case` only warned due to default lint level
}
```
To be honest, I'm not sure whether this is intentional or just an oversight. I've dug the implementation history and searched up issues/PRs but couldn't find any discussion on this.
- `MatchVisitor` doesn't update its lint level when it visits match arms. This leads to check lint attributes on match arms taking no effect on some lints handled by this visitor, namely: `bindings_with_variant_name` and `irrefutable_let_patterns`.
This seems to be a fallout from #108504. Before 05082f57af, when the visitor operated on HIR rather than THIR, check lint attributes for the said lints were effective. [This playground][play] compiles successfully on current stable (1.69) but fails on current beta and nightly.
I wasn't sure where best to place the test for this. Let me know if there's a better place.
[play]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=38432b79e535cb175f8f7d6d236d29c3
[play-match]: https://play.rust-lang.org/?version=beta&mode=debug&edition=2021&gist=629aa71b7c84b269beadeba664e2221d
Dont check `must_use` on nested `impl Future` from fn
Fixes (but does not close, per beta policy) #111484
Also fixes a `FIXME` left in the code about (presumably) false-positives on non-async `#[must_use] fn() -> impl Future` cases, though if that's not desirable to include in the beta backport then I can certainly revert it.
Beta nominating as it fixes a beta ICE.
Document that `missing_copy_implementations` and `missing_debug_implementations` only apply to public items.
I encountered #111359 (fixed) and noticed that the documentation didn't say that it was _intended_ that `missing_debug_implementations` only applies to public items. This PR fixes that, and makes the same wording change to `missing_copy_implementations` which has the same condition.
I chose the words to also be similar to `missing_docs` which already had such a remark.
Introduce `DynSend` and `DynSync` auto trait for parallel compiler
part of parallel-rustc #101566
This PR introduces `DynSend / DynSync` trait and `FromDyn / IntoDyn` structure in rustc_data_structure::marker. `FromDyn` can dynamically check data structures for thread safety when switching to parallel environments (such as calling `par_for_each_in`). This happens only when `-Z threads > 1` so it doesn't affect single-threaded mode's compile efficiency.
r? `@cjgillot`
Uplift `clippy::{drop,forget}_{ref,copy}` lints
This PR aims at uplifting the `clippy::drop_ref`, `clippy::drop_copy`, `clippy::forget_ref` and `clippy::forget_copy` lints.
Those lints are/were declared in the correctness category of clippy because they lint on useless and most probably is not what the developer wanted.
## `drop_ref` and `forget_ref`
The `drop_ref` and `forget_ref` lint checks for calls to `std::mem::drop` or `std::mem::forget` with a reference instead of an owned value.
### Example
```rust
let mut lock_guard = mutex.lock();
std::mem::drop(&lock_guard) // Should have been drop(lock_guard), mutex
// still locked
operation_that_requires_mutex_to_be_unlocked();
```
### Explanation
Calling `drop` or `forget` on a reference will only drop the reference itself, which is a no-op. It will not call the `drop` or `forget` method on the underlying referenced value, which is likely what was intended.
## `drop_copy` and `forget_copy`
The `drop_copy` and `forget_copy` lint checks for calls to `std::mem::forget` or `std::mem::drop` with a value that derives the Copy trait.
### Example
```rust
let x: i32 = 42; // i32 implements Copy
std::mem::forget(x) // A copy of x is passed to the function, leaving the
// original unaffected
```
### Explanation
Calling `std::mem::forget` [does nothing for types that implement Copy](https://doc.rust-lang.org/std/mem/fn.drop.html) since the value will be copied and moved into the function on invocation.
-----
Followed the instructions for uplift a clippy describe here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
cc `@m-ou-se` (as T-libs-api leader because the uplifting was discussed in a recent meeting)
While experienced Rustaceans no doubt know this sort of thing already, as more of a newbie I had trouble understanding why I was triggering the lint.
Hopefully this expanded explanation saves someone else some head-scratching.
Introduce `AliasKind::Inherent` for inherent associated types
Allows us to check (possibly generic) inherent associated types for well-formedness.
Type inference now also works properly.
Follow-up to #105961. Supersedes #108430.
Fixes#106722.
Fixes#108957.
Fixes#109768.
Fixes#109789.
Fixes#109790.
~Not to be merged before #108860 (`AliasKind::Weak`).~
CC `@jackh726`
r? `@compiler-errors`
`@rustbot` label T-types F-inherent_associated_types
