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Robert Spencer
acc3842d43
This lint checks for code that looks like
```rust
let something : Vec<_> = (0..100).map(|_| {
1 + 2 + 3
}).collect();
```
which is more clear as
```rust
let something : Vec<_> = std::iter::repeat_with(|| {
1 + 2 + 3
}).take(100).collect();
```
or
```rust
let something : Vec<_> =
std::iter::repeat_n(1 + 2 + 3, 100)
.collect();
```
That is, a map over a range which does nothing with the parameter
passed to it is simply a function (or closure) being called `n`
times and could be more semantically expressed using `take`.
21 lines
774 B
Plaintext
21 lines
774 B
Plaintext
error: this call to `map()` won't have an effect on the call to `count()`
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--> tests/ui/suspicious_map.rs:5:13
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LL | let _ = (0..3).map(|x| x + 2).count();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= help: make sure you did not confuse `map` with `filter`, `for_each` or `inspect`
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= note: `-D clippy::suspicious-map` implied by `-D warnings`
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= help: to override `-D warnings` add `#[allow(clippy::suspicious_map)]`
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error: this call to `map()` won't have an effect on the call to `count()`
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--> tests/ui/suspicious_map.rs:9:13
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LL | let _ = (0..3).map(f).count();
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| ^^^^^^^^^^^^^^^^^^^^^
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= help: make sure you did not confuse `map` with `filter`, `for_each` or `inspect`
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error: aborting due to 2 previous errors
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