Handle false positive with map_clone

Author: maekawatoshiki

clippy_lints/src/methods/map_clone.rs

@@ -86,8 +86,11 @@ pub(super) fn check(cx: &LateContext<'_>, e: &hir::Expr<'_>, recv: &hir::Expr<'_
                                     }
                                 }
                             },
-                            hir::ExprKind::Call(call, [_]) => {
-                                if let hir::ExprKind::Path(qpath) = call.kind {
+                            hir::ExprKind::Call(call, args) => {
+                                if let hir::ExprKind::Path(qpath) = call.kind
+                                    && let [arg] = args
+                                    && ident_eq(name, arg)
+                                {
                                     handle_path(cx, call, &qpath, e, recv);
                                 }
                             },
@@ -119,6 +122,9 @@ fn handle_path(
             && let args = args.as_slice()
             && let Some(ty) = args.iter().find_map(|generic_arg| generic_arg.as_type())
             && ty.is_ref()
+            && let ty::Ref(_, ty, Mutability::Not) = ty.kind()
+            && let ty::FnDef(_, lst) = cx.typeck_results().expr_ty(arg).kind()
+            && lst.iter().all(|l| l.as_type() == Some(*ty))
         {
             lint_path(cx, e.span, recv.span, is_copy(cx, ty.peel_refs()));
         }

tests/ui/map_clone.fixed

@@ -6,7 +6,8 @@
     clippy::redundant_clone,
     clippy::redundant_closure,
     clippy::useless_asref,
-    clippy::useless_vec
+    clippy::useless_vec,
+    clippy::empty_loop
 )]
 
 fn main() {
@@ -117,4 +118,17 @@ fn main() {
     let y = x.as_ref().map(|x| String::clone(x));
     let x: Result<String, ()> = Ok(String::new());
     let y = x.as_ref().map(|x| String::clone(x));
+
+    // Issue #12271
+    {
+        // Don't lint these
+        let x: Option<&u8> = None;
+        let y = x.map(|x| String::clone(loop {}));
+        let x: Option<&u8> = None;
+        let y = x.map(|x| u8::clone(loop {}));
+        let x: Vec<&u8> = vec![];
+        let y = x.into_iter().map(|x| String::clone(loop {}));
+        let x: Vec<&u8> = vec![];
+        let y = x.into_iter().map(|x| u8::clone(loop {}));
+    }
 }

tests/ui/map_clone.rs

@@ -6,7 +6,8 @@
     clippy::redundant_clone,
     clippy::redundant_closure,
     clippy::useless_asref,
-    clippy::useless_vec
+    clippy::useless_vec,
+    clippy::empty_loop
 )]
 
 fn main() {
@@ -117,4 +118,17 @@ fn main() {
     let y = x.as_ref().map(|x| String::clone(x));
     let x: Result<String, ()> = Ok(String::new());
     let y = x.as_ref().map(|x| String::clone(x));
+
+    // Issue #12271
+    {
+        // Don't lint these
+        let x: Option<&u8> = None;
+        let y = x.map(|x| String::clone(loop {}));
+        let x: Option<&u8> = None;
+        let y = x.map(|x| u8::clone(loop {}));
+        let x: Vec<&u8> = vec![];
+        let y = x.into_iter().map(|x| String::clone(loop {}));
+        let x: Vec<&u8> = vec![];
+        let y = x.into_iter().map(|x| u8::clone(loop {}));
+    }
 }