Implement raw lifetimes and labels (`'r#ident`)
This PR does two things:
1. Reserve lifetime prefixes, e.g. `'prefix#lt` in edition 2021.
2. Implements raw lifetimes, e.g. `'r#async` in edition 2021.
This PR additionally extends the `keyword_idents_2024` lint to also check lifetimes.
cc `@traviscross`
r? parser
Make it crystal clear what lint `type_alias_bounds` actually signifies
This is part of my work on https://github.com/rust-lang/rust/labels/F-lazy_type_alias ([tracking issue](#112792)).
---
To recap, the lint `type_alias_bounds` detects bounds on generic parameters and where clauses on (eager) type aliases. These bounds should've never been allowed because they are currently neither enforced[^1] at usage sites of type aliases nor thoroughly checked for correctness at definition sites due to the way type aliases are represented in the compiler. Allowing them was an oversight.
Explicitly label this as a known limitation of the type checker/system and establish the experimental feature `lazy_type_alias` as its eventual proper solution.
Where this becomes a bit tricky (for me as a rustc dev) are the "secondary effects" of these bounds whose existence I sadly can't deny. As a matter of fact, type alias bounds do play some small roles during type checking. However, after a lot of thinking over the last two weeks I've come to the conclusion (not without second-guessing myself though) that these use cases should not trump the fact that these bounds are currently *inherently broken*. Therefore the lint `type_alias_bounds` should and will continue to flag bounds that may have subordinate uses.
The two *known* secondary effects are:
1. They may enable the use of "shorthand" associated type paths `T::Assoc` (as opposed to fully qualified paths `<T as Trait>::Assoc`) where `T` is a type param bounded by some trait `Trait` which defines that assoc ty.
2. They may affect the default lifetime of trait object types passed as a type argument to the type alias. That concept is called (trait) object lifetime default.
The second one is negligible, no question asked. The first one however is actually "kinda nice" (for writability) and comes up in practice from time to time.
So why don't I just special-case trait bounds that "define" shorthand assoc type paths as originally planned in #125709?
1. Starting to permit even a tiny subset of bounds would already be enough to send a signal to users that bounds in type aliases have been legitimized and that they can expect to see type alias bounds in the wild from now on (proliferation). This would be actively misleading and dangerous because those bounds don't behave at all like one would expect, they are *not real*[^2]!
1. Let's take `type A<T: Trait> = T::Proj;` for example. Everywhere else in the language `T: Trait` means `T: Trait + Sized`. For type aliases, that's not the case though: `T: Trait` and `T: Trait + ?Sized` for that matter do neither mean `T: Trait + Sized` nor `T: Trait + ?Sized` (for both!). Instead, whether `T` requires `Sized` or not entirely depends on the definition of `Trait`[^2]. Namely, whether or not it is bounded by `Sized`.
2. Given `type A<T: Trait<AssocA = ()>> = T::AssocB;`, while `X: Trait` gets checked given `A<X>` (by virtue of projection wfchecking post alias expansion[^2]), the associated type constraint `AssocA = ()` gets dropped entirely! While we could choose to warn on such cases, it would inevitably lead to a huge pile of special cases.
3. While it's common knowledge that the body / aliased type / RHS of an (eager) type alias does not get checked for well-formedness, I'm not sure if people would realize that that extends to bounds as well. Namely, `type A<T: Trait<[u8]>> = T::Proj;` compiles even if `Trait`'s generic parameter requires `Sized`. Of course, at usage sites `[u8]: Sized` would still end up getting checked[^2], so it's not a huge problem if you have full control over `A`. However, imagine that `A` was actually part of a public API and was never used inside the defining crate (not unreasonable). In such a scenario, downstream users would be presented with an impossible to use type alias! Remember, bounds may grow arbitrarily complex and nuanced in practice.
4. Even if we allowed trait bounds that "define" shorthand assoc type paths, we would still need to continue to warn in cases where the assoc ty comes from a supertrait despite the fact that the shorthand syntax can be used: `type A<T: Sub> = T::Assoc;` does compile given `trait Sub: Super {}` and `trait Super { type Assoc; }`. However, `A<X>` does not enforce `X: Sub`, only `X: Super`[^2]. All that to say, type alias bounds are simply not real and we shouldn't pretend they are!
5. Summarizing the points above, we would be legitimizing bounds that are completely broken!
2. It's infeasible to implement: Due to the lack of `TypeckResults` in `ItemCtxt` (and a way to propagate it to other parts of the compiler), the resolution of type-dependent paths in non-`Body` items (most notably type aliases) is not recoverable from the HIR alone which would be necessary because the information of whether an associated type path (projection) is a shorthand is only present pre&in-HIR and doesn't survive HIR ty lowering. Of course, I could rerun parts of HIR ty lowering inside the lint `type_alias_bounds` (namely, `probe_single_ty_param_bound_for_assoc_ty` which would need to be exposed or alternatively a stripped-down version of it). This likely has a performance impact and introduces complexity. In short, the "benefits" are not worth the costs.
---
* 3rd commit: Update a diagnostic to avoid suggesting type alias bounds
* 4th commit: Flag type alias bounds even if the RHS contains inherent associated types.
* I started to allow them at some point in the past which was not correct (see commit for details)
* 5th commit: Allow type alias bounds if the RHS contains const projections and GCEs are enabled
* (and add a `FIXME(generic_const_exprs)` to be revisited before (M)GCE's stabilization)
* As a matter of fact type alias bounds are enforced in this case because the contained AnonConsts do get checked for well-formedness and crucially they inherit the generics and predicates of their parent item (here: the type alias)
* Remaining commits: Improve the lint `type_alias_bounds` itself
---
Fixes#125789 (sugg diag fix).
Fixes#125709 (wontfix, acknowledgement, sugg diag applic fix).
Fixes#104918 (sugg diag applic fix).
Fixes#100270 (wontfix, acknowledgement, sugg diag applic fix).
Fixes#94398 (true fix).
r? `@compiler-errors` `@oli-obk`
[^1]: From the perspective of the trait solver.
[^2]: Given `type A<T: Trait> = T::Proj;`, the reason why the trait bound "`T: Trait`" gets *seemingly* enforced at usage sites of the type alias `A` is simply because `A<X>` gets expanded to "`<X as Trait>::Proj`" very early on and it's the *expansion* that gets checked for well-formedness, not the type alias reference.
Implement lint against ambiguous negative literals
This PR implements a lint against ambiguous negative literals with a literal and method calls right after it.
## `ambiguous_negative_literals`
(deny-by-default)
The `ambiguous_negative_literals` lint checks for cases that are confusing between a negative literal and a negation that's not part of the literal.
### Example
```rust,compile_fail
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```
### Explanation
Method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.
<details>
<summary>Old proposed lint</summary>
## `ambiguous_unary_precedence`
(deny-by-default)
The `ambiguous_unary_precedence` lint checks for use the negative unary operator with a literal and method calls.
### Example
```rust
-1i32.abs(); // equals -1, while `(-1i32).abs()` equals 1
```
### Explanation
Unary operations take precedence on binary operations and method calls take precedence over unary precedence. Setting the precedence explicitly makes the code clearer and avoid potential bugs.
</details>
-----
Note: This is a strip down version of https://github.com/rust-lang/rust/pull/117161, without the binary op precedence.
Fixes https://github.com/rust-lang/rust/issues/117155
`@rustbot` labels +I-lang-nominated
cc `@scottmcm`
r? compiler
Change `binary_asm_labels` to only fire on x86 and x86_64
In <https://github.com/rust-lang/rust/pull/126922>, the `binary_asm_labels` lint was added which flags labels such as `0:` and `1:`. Before that change, LLVM was giving a confusing error on x86/x86_64 because of an incorrect interpretation.
However, targets other than x86 and x86_64 never had the error message and have not been a problem. This means that the lint was causing code that previously worked to start failing (e.g. `compiler_builtins`), rather than only providing a more clear messages where there has always been an error.
Adjust the lint to only fire on x86 and x86_64 assembly to avoid this regression.
Also update the help message.
Fixes: https://github.com/rust-lang/rust/issues/127821
The link pointed to a closed issue. Create a new one and point the link
to it.
Also add a help message to hint what change the user could make.
Fixes: https://github.com/rust-lang/rust/issues/127821
add lint for inline asm labels that look like binary
fixes#94426
Due to a bug/feature in LLVM, labels composed of only the digits `0` and `1` can sometimes be confused with binary literals, even if a binary literal would not be valid in that position.
This PR adds detection for such labels and also as a drive-by change, adds a note to cases such as `asm!(include_str!("file"))` that the label that it found came from an expansion of a macro, it wasn't found in the source code.
I expect this PR to upset some people that were using labels `0:` or `1:` without issue because they never hit the case where LLVM got it wrong, but adding a heuristic to the lint to prevent this is not feasible - it would involve writing a whole assembly parser for every target that we have assembly support for.
[zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202024-06-20/near/445870628)
r? ``@estebank``
This is adding a migration lint for the current (in the 2021 edition and previous)
to move expr to expr_2021 from expr
Co-Developed-by: Eric Holk
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Suggest using a standalone doctest for non-local impl defs
This PR tweaks the lint output of the `non_local_definitions` lint to suggest using a standalone doctest instead of a moving the `impl` def to an impossible place as was already done with `macro_rules!` case in https://github.com/rust-lang/rust/pull/124568.
Fixes#126339
r? ```@fmease```
Resolve elided lifetimes in assoc const to static if no other lifetimes are in scope
Implements the change to elided lifetime resolution in *associated consts* subject to FCP here: https://github.com/rust-lang/rust/issues/125190#issue-2301532282
Specifically, walk the enclosing lifetime ribs in an associated const, and if we find no other lifetimes, then resolve to `'static`.
Also make it work for traits, but don't lint -- just give a hard error in that case.
Spruce up the diagnostics of some early lints
Implement the various "*(note to myself) in a follow-up PR we should turn parts of this message into a subdiagnostic (help msg or even struct sugg)*" drive-by comments I left in #124417 during my review.
For context, before #124417, only a few early lints touched/decorated/customized their diagnostic because the former API made it a bit awkward. Likely because of that, things that should've been subdiagnostics were just crammed into the primary message. This PR rectifies this.
Convert `proc_macro_back_compat` lint to an unconditional error.
We still check for the `rental`/`allsorts-rental` crates. But now if they are detected we just emit a fatal error, instead of emitting a warning and providing alternative behaviour.
The original "hack" implementing alternative behaviour was added in #73345.
The lint was added in #83127.
The tracking issue is #83125.
The direct motivation for the change is that providing the alternative behaviour is interfering with #125174 and follow-on work.
r? ``@estebank``
A small diagnostic improvement for dropping_copy_types
For a value `m` which implements `Copy` trait, `drop(m);` does nothing.
We now suggest user to ignore it by a abstract and general note: `let _ = ...`.
I think we can give a clearer note here: `let _ = m;`
fixes#125189
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We still check for the `rental`/`allsorts-rental` crates. But now if
they are detected we just emit a fatal error, instead of emitting a
warning and providing alternative behaviour.
The original "hack" implementing alternative behaviour was added
in #73345.
The lint was added in #83127.
The tracking issue is #83125.
The direct motivation for the change is that providing the alternative
behaviour is interfering with #125174 and follow-on work.
[perf] Delay the construction of early lint diag structs
Attacks some of the perf regressions from https://github.com/rust-lang/rust/pull/124417#issuecomment-2123700666.
See individual commits for details. The first three commits are not strictly necessary.
However, the 2nd one (06bc4fc671, *Remove `LintDiagnostic::msg`*) makes the main change way nicer to implement.
It's also pretty sweet on its own if I may say so myself.
Don't suggest adding the unexpected cfgs to the build-script it-self
This PR adds a check to avoid suggesting to add the unexpected cfgs inside the build-script when building the build-script it-self, as it won't have any effect, since build-scripts applies to their descended target.
Fixes#125368
Cleanup: Fix up some diagnostics
Several diagnostics contained their error code inside their primary message which is no bueno.
This PR moves them out of the message and turns them into structured error codes.
Also fixes another occurrence of `->` after a selector in a Fluent message which is not correct. I've fixed two other instances of this issue in #104345 (2022) but didn't update all instances as I've noted here: https://github.com/rust-lang/rust/pull/104345#issuecomment-1312705977 (“the future is now!”).
Expand `for_loops_over_fallibles` lint to lint on fallibles behind references.
Extends the scope of the (warn-by-default) lint `for_loops_over_fallibles` from just `for _ in x` where `x: Option<_>/Result<_, _>` to also cover `x: &(mut) Option<_>/Result<_>`
```rs
fn main() {
// Current lints
for _ in Some(42) {}
for _ in Ok::<_, i32>(42) {}
// New lints
for _ in &Some(42) {}
for _ in &mut Some(42) {}
for _ in &Ok::<_, i32>(42) {}
for _ in &mut Ok::<_, i32>(42) {}
// Should not lint
for _ in Some(42).into_iter() {}
for _ in Some(42).iter() {}
for _ in Some(42).iter_mut() {}
for _ in Ok::<_, i32>(42).into_iter() {}
for _ in Ok::<_, i32>(42).iter() {}
for _ in Ok::<_, i32>(42).iter_mut() {}
}
```
<details><summary><code>cargo build</code> diff</summary>
```diff
diff --git a/old.out b/new.out
index 84215aa..ca195a7 100644
--- a/old.out
+++ b/new.out
`@@` -1,33 +1,93 `@@`
warning: for loop over an `Option`. This is more readably written as an `if let` statement
--> src/main.rs:3:14
|
3 | for _ in Some(42) {}
| ^^^^^^^^
|
= note: `#[warn(for_loops_over_fallibles)]` on by default
help: to check pattern in a loop use `while let`
|
3 | while let Some(_) = Some(42) {}
| ~~~~~~~~~~~~~~~ ~~~
help: consider using `if let` to clear intent
|
3 | if let Some(_) = Some(42) {}
| ~~~~~~~~~~~~ ~~~
warning: for loop over a `Result`. This is more readably written as an `if let` statement
--> src/main.rs:4:14
|
4 | for _ in Ok::<_, i32>(42) {}
| ^^^^^^^^^^^^^^^^
|
help: to check pattern in a loop use `while let`
|
4 | while let Ok(_) = Ok::<_, i32>(42) {}
| ~~~~~~~~~~~~~ ~~~
help: consider using `if let` to clear intent
|
4 | if let Ok(_) = Ok::<_, i32>(42) {}
| ~~~~~~~~~~ ~~~
-warning: `for-loops-over-fallibles` (bin "for-loops-over-fallibles") generated 2 warnings
- Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.04s
+warning: for loop over a `&Option`. This is more readably written as an `if let` statement
+ --> src/main.rs:7:14
+ |
+7 | for _ in &Some(42) {}
+ | ^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+7 | while let Some(_) = &Some(42) {}
+ | ~~~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+7 | if let Some(_) = &Some(42) {}
+ | ~~~~~~~~~~~~ ~~~
+
+warning: for loop over a `&mut Option`. This is more readably written as an `if let` statement
+ --> src/main.rs:8:14
+ |
+8 | for _ in &mut Some(42) {}
+ | ^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+8 | while let Some(_) = &mut Some(42) {}
+ | ~~~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+8 | if let Some(_) = &mut Some(42) {}
+ | ~~~~~~~~~~~~ ~~~
+
+warning: for loop over a `&Result`. This is more readably written as an `if let` statement
+ --> src/main.rs:9:14
+ |
+9 | for _ in &Ok::<_, i32>(42) {}
+ | ^^^^^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+9 | while let Ok(_) = &Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+9 | if let Ok(_) = &Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~ ~~~
+
+warning: for loop over a `&mut Result`. This is more readably written as an `if let` statement
+ --> src/main.rs:10:14
+ |
+10 | for _ in &mut Ok::<_, i32>(42) {}
+ | ^^^^^^^^^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+10 | while let Ok(_) = &mut Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+10 | if let Ok(_) = &mut Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~ ~~~
+
+warning: `for-loops-over-fallibles` (bin "for-loops-over-fallibles") generated 6 warnings
+ Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.02s
```
</details>
-----
Question:
* ~~Currently, the article `an` is used for `&Option`, and `&mut Option` in the lint diagnostic, since that's what `Option` uses. Is this okay or should it be changed? (likewise, `a` is used for `&Result` and `&mut Result`)~~ The article `a` is used for `&Option`, `&mut Option`, `&Result`, `&mut Result` and (as before) `Result`. Only `Option` uses `an` (as before).
`@rustbot` label +A-lint
* instead simply set the primary message inside the lint decorator functions
* it used to be this way before [#]101986 which introduced `msg` to prevent
good path delayed bugs (which no longer exist) from firing under certain
circumstances when lints were suppressed / silenced
* this is no longer necessary for various reasons I presume
* it shaves off complexity and makes further changes easier to implement
Diagnostic renaming
Renaming various diagnostic types from `Diagnostic*` to `Diag*`. Part of https://github.com/rust-lang/compiler-team/issues/722. There are more to do but this is enough for one PR.
r? `@davidtwco`
It's a specialized form of the `UntranslatableDiagnostic` lint that is
deny-by-default.
Now that `UntranslatableDiagnostic` has been changed from
allow-by-default to deny-by-default, the trivial variant is no longer
needed.
Split Diagnostics for Uncommon Codepoints: Add Individual Identifier Types
This pull request further modifies the `uncommon_codepoints` lint, adding the individual identifier types of `Technical`, `Not_NFKC`, `Exclusion` and `Limited_Use` to the diagnostic message.
Example rendered diagnostic:
```
error: identifier contains a Unicode codepoint that is not used in normalized strings: 'ij'
--> $DIR/lint-uncommon-codepoints.rs:6:4
|
LL | fn dijkstra() {}
| ^^^^^^^
= note: this character is included in the Not_NFKC Unicode general security profile
```
Second step of #120228.
When encountering `<&T as Clone>::clone(x)` because `T: Clone`, suggest `#[derive(Clone)]`
CC #40699.
```
warning: call to `.clone()` on a reference in this situation does nothing
--> $DIR/noop-method-call.rs:23:71
|
LL | let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
| ^^^^^^^^
|
= note: the type `PlainType<u32>` does not implement `Clone`, so calling `clone` on `&PlainType<u32>` copies the reference, which does not do anything and can be removed
help: remove this redundant call
|
LL - let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
LL + let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref;
|
help: if you meant to clone `PlainType<u32>`, implement `Clone` for it
|
LL + #[derive(Clone)]
LL | struct PlainType<T>(T);
|
```
Downgrade ambiguous_wide_pointer_comparisons suggestions to MaybeIncorrect
In certain cases like #121330, it is possible to have more than one suggestion from the `ambiguous_wide_pointer_comparisons` lint (which before this PR are `MachineApplicable`). When this gets passed to rustfix, rustfix makes *multiple* changes according to the suggestions which result in incorrect code.
This is a temporary workaround. The real long term solution to problems like these is to address <https://github.com/rust-lang/rust/issues/53934>.
This PR also includes a drive-by edit to the panic message emitted by compiletest because "ui" test suite now uses `//`@`` directives.
Fixes#121330.
It is possible to have more than one valid suggestion, which when
applied together via rustfix causes the code to no longer compile.
This is a temporary workaround; the real long term solution to these
issues is to solve <https://github.com/rust-lang/rust/issues/53934>.
Trigger `unsafe_code` lint on invocations of `global_asm`
`unsafe_code` already warns about things that don't involve the `unsafe` keyword, e.g. `#[no_mangle]`. This makes it warn on `core::arch::global_asm` too.
Fixes#103078
Currently many diagnostic modifier methods are available on both
`Diagnostic` and `DiagnosticBuilder`. This commit removes most of them
from `Diagnostic`. To minimize the diff size, it keeps them within
`diagnostic.rs` but changes the surrounding `impl Diagnostic` block to
`impl DiagnosticBuilder`. (I intend to move things around later, to give
a more sensible code layout.)
`Diagnostic` keeps a few methods that it still needs, like `sub`,
`arg`, and `replace_args`.
The `forward!` macro, which defined two additional methods per call
(e.g. `note` and `with_note`), is replaced by the `with_fn!` macro,
which defines one additional method per call (e.g. `with_note`). It's
now also only used when necessary -- not all modifier methods currently
need a `with_*` form. (New ones can be easily added as necessary.)
All this also requires changing `trait AddToDiagnostic` so its methods
take `DiagnosticBuilder` instead of `Diagnostic`, which leads to many
mechanical changes. `SubdiagnosticMessageOp` gains a type parameter `G`.
There are three subdiagnostics -- `DelayedAtWithoutNewline`,
`DelayedAtWithNewline`, and `InvalidFlushedDelayedDiagnosticLevel` --
that are created within the diagnostics machinery and appended to
external diagnostics. These are handled at the `Diagnostic` level, which
means it's now hard to construct them via `derive(Diagnostic)`, so
instead we construct them by hand. This has no effect on what they look
like when printed.
There are lots of new `allow` markers for `untranslatable_diagnostics`
and `diagnostics_outside_of_impl`. This is because
`#[rustc_lint_diagnostics]` annotations were present on the `Diagnostic`
modifier methods, but missing from the `DiagnosticBuilder` modifier
methods. They're now present.
errors: only eagerly translate subdiagnostics
Subdiagnostics don't need to be lazily translated, they can always be eagerly translated. Eager translation is slightly more complex as we need to have a `DiagCtxt` available to perform the translation, which involves slightly more threading of that context.
This slight increase in complexity should enable later simplifications - like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages into the diagnostic structs rather than having them in separate files (working on that was what led to this change).
r? ```@nnethercote```
Subdiagnostics don't need to be lazily translated, they can always be
eagerly translated. Eager translation is slightly more complex as we need
to have a `DiagCtxt` available to perform the translation, which involves
slightly more threading of that context.
This slight increase in complexity should enable later simplifications -
like passing `DiagCtxt` into `AddToDiagnostic` and moving Fluent messages
into the diagnostic structs rather than having them in separate files
(working on that was what led to this change).
Signed-off-by: David Wood <david@davidtw.co>
