mir_to_const improvements
This simplifies some code and also fixes the float array handling to properly take into account the `offset`, and to work with little-endian targets.
Fixes https://github.com/rust-lang/rust-clippy/issues/11488
changelog: none
Improve invalid let expression handling
- Move all of the checks for valid let expression positions to parsing.
- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a valid location.
- Suppress some later errors and MIR construction for invalid let expressions.
- Fix a (drop) scope issue that was also responsible for #104172.
Fixes#104172Fixes#104868
new lint: `iter_out_of_bounds`
Closes#11345
The original idea in the linked issue seemed to be just about arrays afaict, but I extended this to catch some other iterator sources such as `iter::once` or `iter::empty`.
I'm not entirely sure if this name makes a lot of sense now that it's not just about arrays anymore (specifically, not sure if you can call `.take(1)` on an `iter::Empty` to be "out of bounds"?).
changelog: [`iter_out_of_bounds`]: new lint
Update Clippy
r? `@oli-obk` Assigning you, because something broke with ui_test:
```
tests/ui/crashes/ice-7272.rs FAILED:
command: "<unknown>"
A bug in `ui_test` occurred: called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }
full stderr:
```
(and that 103 times)
Thought I would ping you, before starting to investigate. Maybe you know what's going on.
[`unnecessary_unwrap`]: lint on `.as_ref().unwrap()`
Closes#11371
This turned out to be a little more code than I originally thought, because the lint also makes sure to not lint if the user tries to mutate the option:
```rs
if option.is_some() {
option = None;
option.unwrap(); // don't lint here
}
```
... which means that even if we taught this lint to recognize `.as_mut()`, it would *still* not lint because that would count as a mutation. So we need to allow `.as_mut()` calls but reject other kinds of mutations.
Unfortunately it doesn't look like this is possible with `is_potentially_mutated` (seeing what kind of mutation happened).
This replaces it with a custom little visitor that does basically what it did before, but also allows `.as_mut()`.
changelog: [`unnecessary_unwrap`]: lint on `.as_ref().unwrap()`
[`if_then_some_else_none`]: look into local initializers for early returns
Fixes#11394
As the PR title says, problem was that it only looked for early returns in semi statements. Local variables don't count as such, so it didn't count `let _v = x?;` (or even just `let _ = return;`) as a possible early return and didn't realize that it can't lint then.
Imo the `stmts_contains_early_return` function that was used before is redundant. `contains_return` could already do that if we just made the parameter a bit more generic, just like `for_each_expr`, which can already accept `&[Stmt]`
changelog: [`if_then_some_else_none`]: look into local initializers for early returns
Point at return type when it influences non-first `match` arm
When encountering code like
```rust
fn foo() -> i32 {
match 0 {
1 => return 0,
2 => "",
_ => 1,
}
}
```
Point at the return type and not at the prior arm, as that arm has type `!` which isn't influencing the arm corresponding to arm `2`.
Fix#78124.
