Add `never_patterns` feature gate
This PR adds the feature gate and most basic parsing for the experimental `never_patterns` feature. See the tracking issue (https://github.com/rust-lang/rust/issues/118155) for details on the experiment.
`@scottmcm` has agreed to be my lang-team liaison for this experiment.
- Rename them both `as_str`, which is the typical name for a function
that returns a `&str`. (`to_string` is appropriate for functions
returning `String` or maybe `Cow<'a, str>`.)
- Change `UnOp::as_str` from an associated function (weird!) to a
method.
- Avoid needless `self` dereferences.
teach `eager_or_lazy` about panicky arithmetic operations
Fixes#9422Fixes#9814Fixes#11793
It's a bit sad that we have to do this because arithmetic operations seemed to me like the prime example where a closure would not be necessary, but this has "side effects" (changes behavior when going from lazy to eager) as some of these panic on overflow/underflow if compiled with `-Coverflow-checks` (which is the default in debug mode).
Given the number of backlinks in the mentioned issues, this seems to be a FP that is worth fixing, probably.
changelog: [`unnecessary_lazy_evaluations`]: don't lint if closure has panicky arithmetic operations
Implement new lint `iter_over_hash_type`
Implements and fixes https://github.com/rust-lang/rust-clippy/issues/11788
This PR adds a new *restriction* lint `iter_over_hash_type` which prevents `Hash`-types (that is, `HashSet` and `HashMap`) from being used as the iterator in `for` loops.
The justification for this is because in `Hash`-based types, the ordering of items is not guaranteed and may vary between executions of the same program on the same hardware. In addition, it reduces readability due to the unclear iteration order.
The implementation of this lint also ensures the following:
- Calls to `HashMap::keys`, `HashMap::values`, and `HashSet::iter` are also denied when used in `for` loops,
- When this expression is used in procedural macros, it is not linted/denied.
changelog: add new `iter_over_hash_type` lint to prevent unordered iterations through hashed data structures
Don't check for late-bound vars, check for escaping bound vars
Fixes an assertion that didn't make sense. Many valid and well-formed types *have* late-bound vars (e.g. `for<'a> fn(&'a ())`), they just must not have *escaping* late-bound vars in order to be normalized correctly.
Addresses rust-lang/rust-clippy#11230, cc `@jyn514` and `@matthiaskrgr`
changelog: don't check for late-bound vars, check for escaping bound vars. Addresses rust-lang/rust-clippy#11230
Fixes to `manual_let_else`'s divergence check
A few changes to the divergence check in `manual_let_else` and moves it the implementation to `clippy_utils` since it's generally useful:
* Handle internal `break` and `continue` expressions.
e.g. The first loop is divergent, but the second is not.
```rust
{
loop {
break 'outer;
};
}
{
loop {
break;
};
}
```
* Match rust's definition of divergence which is defined via the type system.
e.g. The following is not considered divergent by rustc as the inner block has a result type of `()`:
```rust
{
'a: {
panic!();
break 'a;
};
}
```
* Handle when adding a single semicolon would make the expression divergent.
e.g. The following would be a divergent if a semicolon were added after the `if` expression:
```rust
{ if panic!() { 0 } else { 1 } }
```
changelog: None
Lint `needless_borrow` and `explicit_auto_deref` on most union field accesses
Changes both lints to follow rustc's rules around auto-deref through `ManuallyDrop` union fields rather than just bailing on union fields.
changelog: [`needless_borrow`] & [`explicit_auto_deref`]: Lint on most union field accesses
[`map_identity`]: respect match ergonomics
Fixes#11764
Note: the original tests before this were slightly wrong themselves already and had to be changed. They were calling `map` on an iterator of `&(i32, i32)`s, so this PR would stop linting there, but they were meant to test something else unrelated to binding modes, so I just changed them to remove the references so that it iterates over owned values and they all bind by value. This way they continue to test what they checked for before: the identity function for tuple patterns.
changelog: [`map_identity`]: respect match ergonomics
Make SpanlessEq more consistent
1) Remove wildcard as requested in https://github.com/rust-lang/rust-clippy/issues/10267.
2) Implement `hir_utils::eq_expr` for `ExprKind::Closure`, `ExprKind::ConstBlock`, `ExprKind::InlineAsm` and `ExprKind::Yield`.
3) Reorder branches of `hir_utils::eq_expr` to be in alphabetical order.
---
changelog: none
Most notably, this commit changes the `pub use crate::*;` in that file
to `use crate::*;`. This requires a lot of `use` items in other crates
to be adjusted, because everything defined within `rustc_span::*` was
also available via `rustc_span::source_map::*`, which is bizarre.
The commit also removes `SourceMap::span_to_relative_line_string`, which
is unused.
Remove internal feature from clippy_utils
It's only used to gate a few `const`s, removing the feature gate means it doesn't have to be recompiled when moving between a normal and `-F internal` build/test/etc
changelog: none
