Auto merge of #4043 - rust-lang:map-clone-iter, r=matthiaskrgr

Suggest .copied() for map_clone on iterators too

fixes #3958

changelog: Make `map_clone` suggest the newly-stable `Iterator::copied()` when applicable

r? @mikerite @matthiaskrgr

Author: bors

clippy_lints/src/map_clone.rs

@@ -52,8 +52,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapClone {
             if args.len() == 2;
             if method.ident.as_str() == "map";
             let ty = cx.tables.expr_ty(&args[0]);
-            let is_option = match_type(cx, ty, &paths::OPTION);
-            if is_option || match_trait_method(cx, e, &paths::ITERATOR);
+            if match_type(cx, ty, &paths::OPTION) || match_trait_method(cx, e, &paths::ITERATOR);
             if let hir::ExprKind::Closure(_, _, body_id, _, _) = args[1].node;
             let closure_body = cx.tcx.hir().body(body_id);
             let closure_expr = remove_blocks(&closure_body.value);
@@ -63,16 +62,14 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapClone {
                         hir::BindingAnnotation::Unannotated, .., name, None
                     ) = inner.node {
                         if ident_eq(name, closure_expr) {
-                            // FIXME When Iterator::copied() stabilizes we can remove is_option
-                            // from here and the other lint() calls
-                            lint(cx, e.span, args[0].span, is_option);
+                            lint(cx, e.span, args[0].span, true);
                         }
                     },
                     hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, .., name, None) => {
                         match closure_expr.node {
                             hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner) => {
                                 if ident_eq(name, inner) && !cx.tables.expr_ty(inner).is_box() {
-                                    lint(cx, e.span, args[0].span, is_option);
+                                    lint(cx, e.span, args[0].span, true);
                                 }
                             },
                             hir::ExprKind::MethodCall(ref method, _, ref obj) => {
@@ -82,7 +79,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapClone {
                                     let obj_ty = cx.tables.expr_ty(&obj[0]);
                                     if let ty::Ref(_, ty, _) = obj_ty.sty {
                                         let copy = is_copy(cx, ty);
-                                        lint(cx, e.span, args[0].span, is_option && copy);
+                                        lint(cx, e.span, args[0].span, copy);
                                     } else {
                                         lint_needless_cloning(cx, e.span, args[0].span);
                                     }

tests/ui/map_clone.fixed

@@ -6,9 +6,9 @@
 #![allow(clippy::redundant_closure)]
 
 fn main() {
-    let _: Vec<i8> = vec![5_i8; 6].iter().cloned().collect();
+    let _: Vec<i8> = vec![5_i8; 6].iter().copied().collect();
     let _: Vec<String> = vec![String::new()].iter().cloned().collect();
-    let _: Vec<u32> = vec![42, 43].iter().cloned().collect();
+    let _: Vec<u32> = vec![42, 43].iter().copied().collect();
     let _: Option<u64> = Some(Box::new(16)).map(|b| *b);
     let _: Option<u64> = Some(&16).copied();
     let _: Option<u8> = Some(&1).copied();

tests/ui/map_clone.stderr

@@ -1,8 +1,8 @@
-error: You are using an explicit closure for cloning elements
+error: You are using an explicit closure for copying elements
   --> $DIR/map_clone.rs:9:22
    |
 LL |     let _: Vec<i8> = vec![5_i8; 6].iter().map(|x| *x).collect();
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![5_i8; 6].iter().cloned()`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `copied` method: `vec![5_i8; 6].iter().copied()`
    |
    = note: `-D clippy::map-clone` implied by `-D warnings`
 
@@ -12,11 +12,11 @@ error: You are using an explicit closure for cloning elements
 LL |     let _: Vec<String> = vec![String::new()].iter().map(|x| x.clone()).collect();
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![String::new()].iter().cloned()`
 
-error: You are using an explicit closure for cloning elements
+error: You are using an explicit closure for copying elements
   --> $DIR/map_clone.rs:11:23
    |
 LL |     let _: Vec<u32> = vec![42, 43].iter().map(|&x| x).collect();
-   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `cloned` method: `vec![42, 43].iter().cloned()`
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: Consider calling the dedicated `copied` method: `vec![42, 43].iter().copied()`
 
 error: You are using an explicit closure for copying elements
   --> $DIR/map_clone.rs:13:26