Auto merge of #9745 - matttpt:fix-redundant-closure-for-method-calls-suggestion, r=flip1995

Fix `redundant_closure_for_method_calls` suggestion

Fixes #7746. The issue turns out to be more general than raw pointers. The `redundant_closure_for_method_calls` lint produces incorrect suggestions when the method is associated with a type that must be enclosed in angle brackets or must be written with generic arguments substituted. For example:

```rust
fn main() {
    // Clippy's suggestion: [T; N]::as_slice
    // Correct suggestion:  <[u8; 3]>::as_slice
    let array_opt: Option<&[u8; 3]> = Some(&[4, 8, 7]);
    array_opt.map(|a| a.as_slice());

    // Clippy's suggestion: [T]::len
    // Correct suggestion:  <[u8]>::len
    let slice_opt: Option<&[u8]> = Some(b"slice");
    slice_opt.map(|s| s.len());

    // Clippy's suggestion: *const T::is_null
    // Correct suggestion:  <*const usize>::is_null
    let ptr_opt: Option<*const usize> = Some(&487);
    ptr_opt.map(|p| p.is_null());

    // Clippy's suggestion: dyn TestTrait::method_on_dyn
    // Correct suggestion:  <dyn TestTrait>::method_on_dyn
    let test_struct = TestStruct {};
    let dyn_opt: Option<&dyn TestTrait> = Some(&test_struct);
    dyn_opt.map(|d| d.method_on_dyn());
}

// For the trait object example:
trait TestTrait {}
struct TestStruct {}
impl TestTrait for TestStruct {}

impl dyn TestTrait + '_ {
    fn method_on_dyn(&self) -> bool {
        false
    }
}
```

The issue also affects references and tuples, though I had to patch the standard library with non-trait methods for those types to test that. Just in case, I also included handling for `!`, since it appeared to be possible to call methods on it with angle brackets. I just couldn't verify the resulting suggestion, since dead-code analysis eliminates the code first.

This is my first exposure to Rust compiler internals, so please let me know if I'm taking the wrong approach here!

changelog: [`redundant_closure_for_method_calls`]: add angle brackets and substitute generic arguments in suggestion when needed

0 files changed, 0 insertions, 0 deletions