rust/tests/ui/trait-bounds/argument-with-unnecessary-method-call.rs
Esteban Küber 9b3fcf9ad4 Detect when method call on argument could be removed to fulfill failed trait bound
When encountering

```rust
struct Foo;
struct Bar;
impl From<Bar> for Foo {
    fn from(_: Bar) -> Self { Foo }
}
fn qux(_: impl From<Bar>) {}
fn main() {
    qux(Bar.into());
}
```

Suggest removing `.into()`:

```
error[E0283]: type annotations needed
 --> f100.rs:8:13
  |
8 |     qux(Bar.into());
  |     ---     ^^^^
  |     |
  |     required by a bound introduced by this call
  |
  = note: cannot satisfy `_: From<Bar>`
note: required by a bound in `qux`
 --> f100.rs:6:16
  |
6 | fn qux(_: impl From<Bar>) {}
  |                ^^^^^^^^^ required by this bound in `qux`
help: try using a fully qualified path to specify the expected types
  |
8 |     qux(<Bar as Into<T>>::into(Bar));
  |         +++++++++++++++++++++++   ~
help: consider removing this method call, as the receiver has type `Bar` and `Bar: From<Bar>` can be fulfilled
  |
8 -     qux(Bar.into());
8 +     qux(Bar);
  |
```

Fix #71252
2024-02-16 04:28:05 +00:00

12 lines
380 B
Rust

struct Foo;
struct Bar;
impl From<Bar> for Foo {
fn from(_: Bar) -> Self { Foo }
}
fn qux(_: impl From<Bar>) {}
fn main() {
qux(Bar.into()); //~ ERROR type annotations needed
//~| HELP try using a fully qualified path to specify the expected types
//~| HELP consider removing this method call, as the receiver has type `Bar` and `Bar: From<Bar>` trivially holds
}