Add check if span is from macro expansion
The same thing I did in https://github.com/rust-lang/rust/pull/147416, actually the same bug but in another place, I'm not really sure how this method is good for fixing such ICEs, but, it does work and not conflicting with any existing tests, so I guess, it's fine
Fixes https://github.com/rust-lang/rust/issues/147408
r? compiler
Add new `function_casts_as_integer` lint
The `function_casts_as_integer` lint detects cases where users cast a function pointer into an integer.
*warn-by-default*
### Example
```rust
fn foo() {}
let x = foo as usize;
```
```
warning: casting a function into an integer implicitly
--> $DIR/function_casts_as_integer.rs:9:17
|
LL | let x = foo as usize;
| ^^^^^^^^
|
help: add `fn() as usize`
|
LL | let x = foo as fn() as usize;
| +++++++
```
### Explanation
You should never cast a function directly into an integer but go through a cast as `fn` first to make it obvious what's going on. It also allows to prevent confusion with (associated) constants.
Related to https://github.com/rust-lang/rust/issues/81686 and https://stackoverflow.com/questions/68701177/whats-the-meaning-of-casting-a-rust-enum-variant-to-a-numeric-data-type
r? ````@urgau````
mgca: Add ConstArg representation for const items
tracking issue: rust-lang/rust#132980fixesrust-lang/rust#131046fixesrust-lang/rust#134641
As part of implementing `min_generic_const_args`, we need to distinguish const items that can be used in the type system, such as in associated const equality projections, from const items containing arbitrary const code, which must be kept out of the type system. Specifically, all "type consts" must be either concrete (no generics) or generic with a trivial expression like `N` or a path to another type const item.
To syntactically distinguish these cases, we require, for now at least, that users annotate all type consts with the `#[type_const]` attribute. Then, we validate that the const's right-hand side is indeed eligible to be a type const and represent it differently in the HIR.
We accomplish this representation using a new `ConstItemRhs` enum in the HIR, and a similar but simpler enum in the AST. When `#[type_const]` is **not** applied to a const (e.g. on stable), we represent const item right-hand sides (rhs's) as HIR bodies, like before. However, when the attribute is applied, we instead lower to a `hir::ConstArg`. This syntactically distinguishes between trivial const args (paths) and arbitrary expressions, which are represented using `AnonConst`s. Then in `generics_of`, we can take advantage of the existing machinery to bar the `AnonConst` rhs's from using parent generics.
Implement pin-project in pattern matching for `&pin mut|const T`
This PR implements part of rust-lang/rust#130494. It supports pin-project in pattern matching for `&pin mut|const T`.
~Pin-projection by field access (i.e. `&pin mut|const place.field`) is not fully supported yet since pinned-borrow is not ready (rust-lang/rust#135731).~
CC ``````@traviscross``````
Constify trait aliases
Allow `const trait Foo = Bar + [const] Baz;` trait alias declarations. Their rules are the same as with super traits of const traits. So `[const] Baz` or `const Baz` is only required for `[const] Foo` or `const Foo` bounds respectively.
tracking issue rust-lang/rust#41517 (part of the general trait alias feature gate, but I can split it out into a separate const trait alias feature gate. I just assumed that const traits would stabilize before trait aliases, and we'd want to stabilize trait aliases together with const trait aliases at the same time)
r? ``@compiler-errors`` ``@fee1-dead``
Mark desugared range expression spans with DesugaringKind::RangeExpr
This is a prerequisite to removing `QPath::LangItem` (rust-lang/rust#115178) because otherwise there would be no way to detect a range expression in the HIR.
There are some non-obvious Clippy changes so a Clippy team review would be good.
unused_must_use: Don't warn on `Result<(), Uninhabited>` or `ControlFlow<Uninhabited, ()>`
This suppresses warnings on things like `Result<(), !>`, which helps simplify code using the common pattern of having an `Error` associated type: code will only have to check the error if there is a possibility of error.
This will, for instance, help with future refactorings of `write!` in the standard library.
As this is a user-visible change to lint behavior, it'll require a lang FCP.
---
My proposal, here, is that we handle this simple case to make common patterns more usable. This does not rule out the possibility of adding more cases in the future, including general trait-based cases. However, I don't think we should make this common case wait on the more general cases. In particular, this solution does not close any doors on replacing this special case with a general case.
This would unblock some planned work in the standard library to make `write!` more usable for infallible cases (e.g. writing into a `Vec` or `String`).
Issue-125323: ICE non-ADT in struct pattern when long time constant evaluation is in for loop
This PR fixes#125323
## Context
According to the issue, the ICE happens since #121206.
In the PR, some error methods were reorganized. For example, has_errors() was renamed to has_errors_exclude_lint_errors(). However, some codes which used the original has_errors() were not switched to has_errors_exclude_lint_errors(). I finally found that report_error() in writeback.rs causes this ICE. Currently the method uses tainted_by_errors() to get guar (ErrorGuaranteed), but originally it used dcx().has_errors() but it wasn't changed to has_errors_exclude_lint_errors() when changes in #121206 were merged. I don't think I fully understand how an error is propagated, but I suppose that the error from long time constant evaluation is unexpectedly propagated other parts (in this ICE, for loop), then cause the non-ADT in struct pattern ICE.
## Change
- Fix report_error() in writeback.rs: use dcx().has_errors_exclude_lint_errors() instead of tainted_by_errors() to prevent error propagation from constant evaluation.
- Add test for the ICE
- Modify some tests to align the change: Due to this fix, E0282 error happens (or not happen anymore) in some tests.
## NOTE
The 4th commit aims to revert the fix in #123516 because I confirmed that the ICE solved by the PR doesn't happen if I modify report_error(). I think the root cause of that ICE is the same as #125323 . But I can discard this commit since we can fix#125323 without it.
Result/Option layout guarantee clarifications
- It seems worth spelling out that this guarantee allows particular transmutes.
- After the `Result` section was written, the `Option` section it referenced gained *more* guarantees, saying that `None` is represented as `[0u8; N]`. Those guarantees were not meant to apply to `Result`. Make the `Result` section more self-contained to make this more clear.
- "Type has no fields" is unclear since there is no general definition of what the fields of some arbitrary type are. Replace that by a more accurate description of the actual check implemented [here](e379c77586/compiler/rustc_lint/src/types.rs (L828-L838)).
r? `@traviscross`
mismatched_lifetime_syntax lint refactors and optimizations
I found several opportunities to return early so I'm hoping those will have a perf improvement. Otherwise, it's various refactors for simplicity.
error from const eval lint causes ICE at check_pat in late_lint, because the function expects the typeck result isn't tainted by error but it is.
To avoid the ICE, check_pat returns earlier if the typeck_result is tainted.
check_mod_deathness also has an issue from the same reason. visit_body for making live symbols expects the typeck result has no error.
So this commit adds a check in visit_nested_body to avoid the ICE.
However, if visit_nested_body just returns without doing anything, all codes with the error are marked as dead, because live_symbols is empty.
To avoid this side effect, visit_nested_body and other visit_* functions in MarkSymbolVistior should return appropriate error.
If a function returns ControlFlow::Break, live_symbols_and_ignore_derived_traits returns earlier with error,
then check_mod_deathness, the caller of the function returns earlier without pushing everything into dead_codes.
