should_impl_trait - ignore methods with lifetime params

clippy_lints/src/methods/mod.rs

@@ -1497,11 +1497,20 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 if cx.access_levels.is_exported(impl_item.hir_id) {
                 // check missing trait implementations
                     for &(method_name, n_args, fn_header, self_kind, out_type, trait_name) in &TRAIT_METHODS {
+                        let no_lifetime_params = || {
+                            impl_item.generics.params.iter().filter(|p| match p.kind {
+                               hir::GenericParamKind::Lifetime { .. } => true,
+                               _ => false,
+                            }).count() == 0
+                        };
                         if name == method_name &&
                             sig.decl.inputs.len() == n_args &&
                             out_type.matches(cx, &sig.decl.output) &&
                             self_kind.matches(cx, self_ty, first_arg_ty) &&
-                            fn_header_equals(*fn_header, sig.header) {
+                            fn_header_equals(*fn_header, sig.header) &&
+                            // ignore methods with lifetime params, risk of false positive
+                            no_lifetime_params()
+                             {
                             span_lint(cx, SHOULD_IMPLEMENT_TRAIT, impl_item.span, &format!(
                                 "defining a method called `{}` on this type; consider implementing \
                                 the `{}` trait or choosing a less ambiguous name", name, trait_name));

tests/ui/methods.rs

@@ -10,6 +10,7 @@
     clippy::non_ascii_literal,
     clippy::new_without_default,
     clippy::needless_pass_by_value,
+    clippy::needless_lifetimes,
     clippy::print_stdout,
     clippy::must_use_candidate,
     clippy::use_self,
@@ -82,6 +83,10 @@ impl T {
     fn new(self) -> Self {
         unimplemented!();
     }
+
+    pub fn next<'b>(&'b mut self) -> Option<&'b mut T> {
+        unimplemented!();
+    }
 }
 
 pub struct T1;

tests/ui/methods.stderr

@@ -1,5 +1,5 @@
 error: defining a method called `add` on this type; consider implementing the `std::ops::Add` trait or choosing a less ambiguous name
-  --> $DIR/methods.rs:39:5
+  --> $DIR/methods.rs:40:5
    |
 LL | /     pub fn add(self, other: T) -> T {
 LL | |         self
@@ -9,7 +9,7 @@ LL | |     }
    = note: `-D clippy::should-implement-trait` implied by `-D warnings`
 
 error: methods called `new` usually return `Self`
-  --> $DIR/methods.rs:169:5
+  --> $DIR/methods.rs:174:5
    |
 LL | /     fn new() -> i32 {
 LL | |         0
@@ -19,7 +19,7 @@ LL | |     }
    = note: `-D clippy::new-ret-no-self` implied by `-D warnings`
 
 error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
-  --> $DIR/methods.rs:188:13
+  --> $DIR/methods.rs:193:13
    |
 LL |     let _ = v.iter().filter(|&x| *x < 0).next();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -28,7 +28,7 @@ LL |     let _ = v.iter().filter(|&x| *x < 0).next();
    = note: replace `filter(|&x| *x < 0).next()` with `find(|&x| *x < 0)`
 
 error: called `filter(p).next()` on an `Iterator`. This is more succinctly expressed by calling `.find(p)` instead.
-  --> $DIR/methods.rs:191:13
+  --> $DIR/methods.rs:196:13
    |
 LL |       let _ = v.iter().filter(|&x| {
    |  _____________^
@@ -38,33 +38,33 @@ LL | |                    ).next();
    | |___________________________^
 
 error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:208:22
+  --> $DIR/methods.rs:213:22
    |
 LL |     let _ = v.iter().find(|&x| *x < 0).is_some();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|x| *x < 0)`
    |
    = note: `-D clippy::search-is-some` implied by `-D warnings`
 
 error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:209:20
+  --> $DIR/methods.rs:214:20
    |
 LL |     let _ = (0..1).find(|x| **y == *x).is_some(); // one dereference less
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|x| **y == x)`
 
 error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:210:20
+  --> $DIR/methods.rs:215:20
    |
 LL |     let _ = (0..1).find(|x| *x == 0).is_some();
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|x| x == 0)`
 
 error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:211:22
+  --> $DIR/methods.rs:216:22
    |
 LL |     let _ = v.iter().find(|x| **x == 0).is_some();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|x| *x == 0)`
 
 error: called `is_some()` after searching an `Iterator` with find. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:214:13
+  --> $DIR/methods.rs:219:13
    |
 LL |       let _ = v.iter().find(|&x| {
    |  _____________^
@@ -74,13 +74,13 @@ LL | |                    ).is_some();
    | |______________________________^
 
 error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:220:22
+  --> $DIR/methods.rs:225:22
    |
 LL |     let _ = v.iter().position(|&x| x < 0).is_some();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|&x| x < 0)`
 
 error: called `is_some()` after searching an `Iterator` with position. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:223:13
+  --> $DIR/methods.rs:228:13
    |
 LL |       let _ = v.iter().position(|&x| {
    |  _____________^
@@ -90,13 +90,13 @@ LL | |                    ).is_some();
    | |______________________________^
 
 error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:229:22
+  --> $DIR/methods.rs:234:22
    |
 LL |     let _ = v.iter().rposition(|&x| x < 0).is_some();
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `any(|&x| x < 0)`
 
 error: called `is_some()` after searching an `Iterator` with rposition. This is more succinctly expressed by calling `any()`.
-  --> $DIR/methods.rs:232:13
+  --> $DIR/methods.rs:237:13
    |
 LL |       let _ = v.iter().rposition(|&x| {
    |  _____________^