[`mutex_integer`]: https://github.com/Manishearth/rust-clippy/wiki#mutex_integer
[`needless_bool`]: https://github.com/Manishearth/rust-clippy/wiki#needless_bool
[`needless_borrow`]: https://github.com/Manishearth/rust-clippy/wiki#needless_borrow
+[`needless_borrowed_reference`]: https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference
[`needless_continue`]: https://github.com/Manishearth/rust-clippy/wiki#needless_continue
[`needless_lifetimes`]: https://github.com/Manishearth/rust-clippy/wiki#needless_lifetimes
[`needless_pass_by_value`]: https://github.com/Manishearth/rust-clippy/wiki#needless_pass_by_value
## Lints
-There are 199 lints included in this crate:
+There are 200 lints included in this crate:
name | default | triggers on
-----------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------------------------------------------------------
[mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer) | allow | using a mutex for an integer type
[needless_bool](https://github.com/Manishearth/rust-clippy/wiki#needless_bool) | warn | if-statements with plain booleans in the then- and else-clause, e.g. `if p { true } else { false }`
[needless_borrow](https://github.com/Manishearth/rust-clippy/wiki#needless_borrow) | warn | taking a reference that is going to be automatically dereferenced
+[needless_borrowed_reference](https://github.com/Manishearth/rust-clippy/wiki#needless_borrowed_reference) | warn | taking a needless borrowed reference
[needless_continue](https://github.com/Manishearth/rust-clippy/wiki#needless_continue) | warn | `continue` statements that can be replaced by a rearrangement of code
[needless_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#needless_lifetimes) | warn | using explicit lifetimes for references in function arguments when elision rules would allow omitting them
[needless_pass_by_value](https://github.com/Manishearth/rust-clippy/wiki#needless_pass_by_value) | warn | functions taking arguments by value, but not consuming them in its body
pub mod mutex_atomic;
pub mod needless_bool;
pub mod needless_borrow;
+pub mod needless_borrowed_ref;
pub mod needless_continue;
pub mod needless_pass_by_value;
pub mod needless_update;
needless_bool::BOOL_COMPARISON,
needless_bool::NEEDLESS_BOOL,
needless_borrow::NEEDLESS_BORROW,
+ needless_borrowed_ref::NEEDLESS_BORROWED_REFERENCE,
needless_continue::NEEDLESS_CONTINUE,
needless_pass_by_value::NEEDLESS_PASS_BY_VALUE,
needless_update::NEEDLESS_UPDATE,
--- /dev/null
+//! Checks for useless borrowed references in clojures.
+//!
+//! This lint is **warn** by default
+
+use rustc::lint::*;
+use rustc::hir::{MutImmutable, Pat, PatKind, BindingMode};
+use rustc::ty;
+use utils::{span_lint, in_macro};
+
+/// **What it does:** Checks for useless borrowed references in clojures.
+///
+/// **Why is this bad?** TODO
+///
+/// **Known problems:** None.
+///
+/// **Example:**
+/// ```rust
+/// let mut v = Vec::<String>::new();
+/// let _ = v.iter_mut().filter(|&ref a| a.is_empty());
+/// ```
+/// It could just be |a| a.is_empty()
+declare_lint! {
+ pub NEEDLESS_BORROWED_REFERENCE,
+ Warn,
+ "taking a needless borrowed reference"
+}
+
+#[derive(Copy, Clone)]
+pub struct NeedlessBorrowedRef;
+
+impl LintPass for NeedlessBorrowedRef {
+ fn get_lints(&self) -> LintArray {
+ lint_array!(NEEDLESS_BORROWED_REFERENCE)
+ }
+}
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessBorrowedRef {
+ fn check_pat(&mut self, cx: &LateContext<'a, 'tcx>, pat: &'tcx Pat) {
+ if in_macro(pat.span) {
+ // OK, simple enough, lints doesn't check in macro.
+ return;
+ }
+
+ if_let_chain! {[
+ // Pat is a pattern whose node
+ // is a binding which "involves" a immutable reference...
+ let PatKind::Binding(BindingMode::BindByRef(MutImmutable), ..) = pat.node,
+ // Pattern's type is a reference. Get the type and mutability of referenced value (tam: TypeAndMut).
+ let ty::TyRef(_, ref tam) = cx.tables.pat_ty(pat).sty,
+ // This is an immutable reference.
+ tam.mutbl == MutImmutable,
+ ], {
+ span_lint(cx, NEEDLESS_BORROWED_REFERENCE, pat.span, "this pattern takes a needless borrowed reference")
+ }}
+ }
+}
+