Extend map_clone lint to also work on non-explicit closures

Author: GuillaumeGomez

clippy_lints/src/methods/map_clone.rs

@@ -2,7 +2,7 @@ use clippy_config::msrvs::{self, Msrv};
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::{is_copy, is_type_diagnostic_item};
-use clippy_utils::{is_diag_trait_item, peel_blocks};
+use clippy_utils::{is_diag_trait_item, match_def_path, paths, peel_blocks};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
@@ -19,50 +19,63 @@ pub(super) fn check(cx: &LateContext<'_>, e: &hir::Expr<'_>, recv: &hir::Expr<'_
         && (cx.tcx.impl_of_method(method_id).map_or(false, |id| {
             is_type_diagnostic_item(cx, cx.tcx.type_of(id).instantiate_identity(), sym::Option)
         }) || is_diag_trait_item(cx, method_id, sym::Iterator))
-        && let hir::ExprKind::Closure(&hir::Closure { body, .. }) = arg.kind
     {
-        let closure_body = cx.tcx.hir().body(body);
-        let closure_expr = peel_blocks(closure_body.value);
-        match closure_body.params[0].pat.kind {
-            hir::PatKind::Ref(inner, hir::Mutability::Not) => {
-                if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) = inner.kind {
-                    if ident_eq(name, closure_expr) {
-                        lint_explicit_closure(cx, e.span, recv.span, true, msrv);
-                    }
-                }
-            },
-            hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) => {
-                match closure_expr.kind {
-                    hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
-                        if ident_eq(name, inner) {
-                            if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
+        match arg.kind {
+            hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
+                let closure_body = cx.tcx.hir().body(body);
+                let closure_expr = peel_blocks(closure_body.value);
+                match closure_body.params[0].pat.kind {
+                    hir::PatKind::Ref(inner, hir::Mutability::Not) => {
+                        if let hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) = inner.kind {
+                            if ident_eq(name, closure_expr) {
                                 lint_explicit_closure(cx, e.span, recv.span, true, msrv);
                             }
                         }
                     },
-                    hir::ExprKind::MethodCall(method, obj, [], _) => {
-                        if ident_eq(name, obj) && method.ident.name == sym::clone
-                        && let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
-                        && let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
-                        && cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id)
-                        // no autoderefs
-                        && !cx.typeck_results().expr_adjustments(obj).iter()
-                            .any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
-                        {
-                            let obj_ty = cx.typeck_results().expr_ty(obj);
-                            if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
-                                if matches!(mutability, Mutability::Not) {
-                                    let copy = is_copy(cx, *ty);
-                                    lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
+                    hir::PatKind::Binding(hir::BindingAnnotation::NONE, .., name, None) => {
+                        match closure_expr.kind {
+                            hir::ExprKind::Unary(hir::UnOp::Deref, inner) => {
+                                if ident_eq(name, inner) {
+                                    if let ty::Ref(.., Mutability::Not) = cx.typeck_results().expr_ty(inner).kind() {
+                                        lint_explicit_closure(cx, e.span, recv.span, true, msrv);
+                                    }
                                 }
-                            } else {
-                                lint_needless_cloning(cx, e.span, recv.span);
-                            }
+                            },
+                            hir::ExprKind::MethodCall(method, obj, [], _) => {
+                                if ident_eq(name, obj) && method.ident.name == sym::clone
+                                && let Some(fn_id) = cx.typeck_results().type_dependent_def_id(closure_expr.hir_id)
+                                && let Some(trait_id) = cx.tcx.trait_of_item(fn_id)
+                                && cx.tcx.lang_items().clone_trait().map_or(false, |id| id == trait_id)
+                                // no autoderefs
+                                && !cx.typeck_results().expr_adjustments(obj).iter()
+                                    .any(|a| matches!(a.kind, Adjust::Deref(Some(..))))
+                                {
+                                    let obj_ty = cx.typeck_results().expr_ty(obj);
+                                    if let ty::Ref(_, ty, mutability) = obj_ty.kind() {
+                                        if matches!(mutability, Mutability::Not) {
+                                            let copy = is_copy(cx, *ty);
+                                            lint_explicit_closure(cx, e.span, recv.span, copy, msrv);
+                                        }
+                                    } else {
+                                        lint_needless_cloning(cx, e.span, recv.span);
+                                    }
+                                }
+                            },
+                            _ => {},
                         }
                     },
                     _ => {},
                 }
             },
+            hir::ExprKind::Path(qpath) => {
+                if let Some(path_def_id) = cx.qpath_res(&qpath, arg.hir_id).opt_def_id()
+                    && match_def_path(cx, path_def_id, &paths::CLONE_TRAIT_METHOD)
+                {
+                    // FIXME: Instead of passing `false`, it would be better to infer the type to
+                    // check if it's copyable or not.
+                    lint_explicit_closure(cx, e.span, recv.span, false, msrv);
+                }
+            },
             _ => {},
         }
     }

clippy_lints/src/methods/useless_asref.rs

@@ -22,9 +22,16 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, call_name: &str,
         if base_rcv_ty == base_res_ty && rcv_depth >= res_depth {
             // allow the `as_ref` or `as_mut` if it is followed by another method call
             if let Some(parent) = get_parent_expr(cx, expr)
-                && let hir::ExprKind::MethodCall(segment, ..) = parent.kind
+                && let hir::ExprKind::MethodCall(segment, _, args, _) = parent.kind
                 && segment.ident.span != expr.span
             {
+                // If it is followed by `.map(Clone::clone)`, then the lint is still applicable,
+                // but the suggestion is different.
+                if segment.ident.name.as_str() == "map"
+                    && let [arg] = args
+                {
+                    eprintln!("===> {arg:?}",);
+                }
                 return;
             }