//! This lint is **warn** by default
use rustc::lint::*;
-<<<<<<< HEAD
-use rustc::hir::{MutImmutable, Pat, PatKind, BindingAnnotation};
-=======
-use rustc::hir::{MutImmutable, Pat, PatKind};
-<<<<<<< HEAD
->>>>>>> e30bf721... Improve needless_borrowed_ref and add suggestion to it.
+use rustc::hir::{MutImmutable, Pat, PatKind, BindByRef};
use rustc::ty;
-=======
->>>>>>> 4ae45c87... Improve needless_borrowed_ref lint: remove the hand rolled span part.
use utils::{span_lint_and_then, in_macro, snippet};
-use rustc::hir::BindingMode::BindByRef;
/// **What it does:** Checks for useless borrowed references.
///
-/// **Why is this bad?** It is completely useless and make the code look more
-/// complex than it
+/// **Why is this bad?** It is mostly useless and make the code look more complex than it
/// actually is.
///
-/// **Known problems:** None.
+/// **Known problems:** It seems that the `&ref` pattern is sometimes useful.
+/// For instance in the following snippet:
+/// ```rust
+/// enum Animal {
+/// Cat(u64),
+/// Dog(u64),
+/// }
+///
+/// fn foo(a: &Animal, b: &Animal) {
+/// match (a, b) {
+/// (&Animal::Cat(v), k) | (k, &Animal::Cat(v)) => (), // lifetime mismatch error
+/// (&Animal::Dog(ref c), &Animal::Dog(_)) => ()
+/// }
+/// }
+/// ```
+/// There is a lifetime mismatch error for `k` (indeed a and b have distinct lifetime).
+/// This can be fixed by using the `&ref` pattern.
+/// However, the code can also be fixed by much cleaner ways
///
/// **Example:**
/// ```rust
}}
}
}
+
error: this pattern takes a reference on something that is being de-referenced
- --> examples/needless_borrowed_ref.rs:8:34
+ --> needless_borrowed_ref.rs:8:34
|
8 | let _ = v.iter_mut().filter(|&ref a| a.is_empty());
| ^^^^^^ help: try removing the `&ref` part and just keep `a`
= help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference
error: this pattern takes a reference on something that is being de-referenced
- --> examples/needless_borrowed_ref.rs:13:17
+ --> needless_borrowed_ref.rs:13:17
|
13 | if let Some(&ref v) = thingy {
| ^^^^^^ help: try removing the `&ref` part and just keep `v`
|
- = note: `-D needless-borrowed-reference` implied by `-D warnings`
= help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference
error: this pattern takes a reference on something that is being de-referenced
- --> examples/needless_borrowed_ref.rs:42:27
+ --> needless_borrowed_ref.rs:42:27
|
42 | (&Animal::Cat(v), &ref k) | (&ref k, &Animal::Cat(v)) => (), // lifetime mismatch error if there is no '&ref'
| ^^^^^^ help: try removing the `&ref` part and just keep `k`
|
- = note: `-D needless-borrowed-reference` implied by `-D warnings`
= help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference
error: this pattern takes a reference on something that is being de-referenced
- --> examples/needless_borrowed_ref.rs:42:38
+ --> needless_borrowed_ref.rs:42:38
|
42 | (&Animal::Cat(v), &ref k) | (&ref k, &Animal::Cat(v)) => (), // lifetime mismatch error if there is no '&ref'
| ^^^^^^ help: try removing the `&ref` part and just keep `k`
|
- = note: `-D needless-borrowed-reference` implied by `-D warnings`
= help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference
error: aborting due to previous error(s)