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**What it does:** Checks for generics with `std::ops::Drop` as bounds.
**Why is this bad?** `Drop` bounds do not really accomplish anything.
A type may have compiler-generated drop glue without implementing the
`Drop` trait itself. The `Drop` trait also only has one method,
`Drop::drop`, and that function is by fiat not callable in user code.
So there is really no use case for using `Drop` in trait bounds.
**Known problems:** None.
**Example:**
```rust
fn foo<T: Drop>() {}
```
17 lines
508 B
Plaintext
17 lines
508 B
Plaintext
error: Bounds of the form `T: Drop` are useless. Use `std::mem::needs_drop` to detect if a type has drop glue.
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--> $DIR/drop_bounds.rs:2:11
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LL | fn foo<T: Drop>() {}
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| ^^^^
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= note: #[deny(clippy::drop_bounds)] on by default
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error: Bounds of the form `T: Drop` are useless. Use `std::mem::needs_drop` to detect if a type has drop glue.
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--> $DIR/drop_bounds.rs:3:22
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LL | fn bar<T>() where T: Drop {}
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| ^^^^
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error: aborting due to 2 previous errors
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