None of the tools seem to need syn 0.15.35, so we can just build syn
1.0.
This was causing an issue with clippy's `compile-test` program: since
multiple versions of `syn` would exist in the build directory, we would
non-deterministically pick one based on filesystem iteration order. If
the pre-1.0 version of `syn` was picked, a strange build error would
occur (see
https://github.com/rust-lang/rust/pull/73594#issuecomment-647671463)
To prevent this kind of issue from happening again, we now panic if we
find multiple versions of a crate in the build directly, instead of
silently picking the first version we find.
New lint `match_vec_item`
Added new lint to warn a match on index item which can panic. It's always better to use `get(..)` instead.
Closes#5500
changelog: New lint `match_on_vec_items`
- Show just one error message with multiple suggestions in case of
using multiple times an OS in target family position
- Only suggest #[cfg(unix)] when the OS is in the Unix family
- Test all the operating systems
Don't trigger while_let_on_iterator when the iterator is recreated every iteration
r? @phansch
Fixes#1654
changelog: Fix false positive in [`while_let_on_iterator`]
Downgrade match_bool to pedantic
I don't quite buy the justification in https://rust-lang.github.io/rust-clippy/. The justification is:
> It makes the code less readable.
In the Rust codebases I've worked in, I have found people were comfortable using `match bool` (selectively) to make code more readable. For example, initializing struct fields is a place where the indentation of `match` can work better than the indentation of `if`:
```rust
let _ = Struct {
v: {
...
},
w: match doing_w {
true => ...,
false => ...,
},
x: Nested {
c: ...,
b: ...,
a: ...,
},
y: if doing_y {
...
} else { // :(
...
},
z: ...,
};
```
Or sometimes people prefer something a bit less pithy than `if` when the meaning of the bool doesn't read off clearly from the condition:
```rust
if set.insert(...) {
... // ???
} else {
...
}
match set.insert(...) {
// set.insert returns false if already present
false => ...,
true => ...,
}
```
Or `match` can be a better fit when the bool is playing the role more of a value than a branch condition:
```rust
impl ErrorCodes {
pub fn from(b: bool) -> Self {
match b {
true => ErrorCodes::Yes,
false => ErrorCodes::No,
}
}
}
```
And then there's plain old it's-1-line-shorter, which means we get 25% more content on a screen when stacking a sequence of conditions:
```rust
let old_noun = match old_binding.is_import() {
true => "import",
false => "definition",
};
let new_participle = match new_binding.is_import() {
true => "imported",
false => "defined",
};
```
Bottom line is I think this lint fits the bill better as a pedantic lint; I don't think linting on this by default is justified.
changelog: Remove match_bool from default set of enabled lints
Fixes#4226
This introduces the lint await_holding_lock. For async functions, we iterate
over all types in generator_interior_types and look for types named MutexGuard,
RwLockReadGuard, or RwLockWriteGuard. If we find one then we emit a lint.
If let else mutex
changelog: Adds lint to catch incorrect use of `Mutex::lock` in `if let` expressions with lock calls in any of the blocks.
closes: #5219
