Auto merge of #12104 - GuillaumeGomez:map-clone, r=llogiq

bors · bors · commit 17b241820830 · 2024-01-06T16:54:20.000Z
Extend `map_clone` lint to also work on non-explicit closures

I found it weird that this case was not handled by the current line so I added it. The only thing is that I don't see an obvious way to infer the current type to determine if it's copyable or not, so for now I always suggest `cloned` and I added a FIXME.

r? `@llogiq`

changelog: Extend `map_clone` lint to also work on non-explicit closures
diff --git a/clippy_lints/src/methods/map_clone.rs b/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: It would be better to infer the type to check if it's copyable or not
+                    // to suggest to use `.copied()` instead of `.cloned()` where applicable.
+                    lint_path(cx, e.span, recv.span);
+                }
+            },
             _ => {},
         }
     }
@@ -88,6 +101,23 @@ fn lint_needless_cloning(cx: &LateContext<'_>, root: Span, receiver: Span) {
     );
 }
 
+fn lint_path(cx: &LateContext<'_>, replace: Span, root: Span) {
+    let mut applicability = Applicability::MachineApplicable;
+
+    span_lint_and_sugg(
+        cx,
+        MAP_CLONE,
+        replace,
+        "you are explicitly cloning with `.map()`",
+        "consider calling the dedicated `cloned` method",
+        format!(
+            "{}.cloned()",
+            snippet_with_applicability(cx, root, "..", &mut applicability),
+        ),
+        applicability,
+    );
+}
+
 fn lint_explicit_closure(cx: &LateContext<'_>, replace: Span, root: Span, is_copy: bool, msrv: &Msrv) {
     let mut applicability = Applicability::MachineApplicable;
 
diff --git a/clippy_utils/src/macros.rs b/clippy_utils/src/macros.rs
@@ -420,7 +420,7 @@ pub fn find_format_args(cx: &LateContext<'_>, start: &Expr<'_>, expn_id: ExpnId)
         ast_format_args
             .get()?
             .get(&format_args_expr.span.with_parent(None))
-            .map(Rc::clone)
+            .cloned()
     })
 }
 
diff --git a/tests/ui/useless_asref.fixed b/tests/ui/useless_asref.fixed
@@ -132,6 +132,14 @@ fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
     foo_rt(mru.as_ref());
 }
 
+fn foo() {
+    let x = Some(String::new());
+    let y = x.as_ref().cloned();
+    //~^ ERROR: you are explicitly cloning with `.map()`
+    let y = x.as_ref().cloned();
+    //~^ ERROR: you are explicitly cloning with `.map()`
+}
+
 fn main() {
     not_ok();
     ok();
diff --git a/tests/ui/useless_asref.rs b/tests/ui/useless_asref.rs
@@ -132,6 +132,14 @@ fn generic_ok<U: AsMut<T> + AsRef<T> + ?Sized, T: Debug + ?Sized>(mru: &mut U) {
     foo_rt(mru.as_ref());
 }
 
+fn foo() {
+    let x = Some(String::new());
+    let y = x.as_ref().map(Clone::clone);
+    //~^ ERROR: you are explicitly cloning with `.map()`
+    let y = x.as_ref().map(String::clone);
+    //~^ ERROR: you are explicitly cloning with `.map()`
+}
+
 fn main() {
     not_ok();
     ok();
diff --git a/tests/ui/useless_asref.stderr b/tests/ui/useless_asref.stderr
@@ -70,5 +70,20 @@ error: this call to `as_ref` does nothing
 LL |     foo_rt(mrt.as_ref());
    |            ^^^^^^^^^^^^ help: try: `mrt`
 
-error: aborting due to 11 previous errors
+error: you are explicitly cloning with `.map()`
+  --> $DIR/useless_asref.rs:137:13
+   |
+LL |     let y = x.as_ref().map(Clone::clone);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `x.as_ref().cloned()`
+   |
+   = note: `-D clippy::map-clone` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::map_clone)]`
+
+error: you are explicitly cloning with `.map()`
+  --> $DIR/useless_asref.rs:139:13
+   |
+LL |     let y = x.as_ref().map(String::clone);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider calling the dedicated `cloned` method: `x.as_ref().cloned()`
+
+error: aborting due to 13 previous errors
 

Original file line number	Diff line number	Diff line change
`@@ -420,7 +420,7 @@ pub fn find_format_args(cx: &LateContext<'_>, start: &Expr<'_>, expn_id: ExpnId)`
`420`	`420`	`ast_format_args`
`421`	`421`	`.get()?`
`422`	`422`	`.get(&format_args_expr.span.with_parent(None))`
`423`		`- .map(Rc::clone)`
	`423`	`+ .cloned()`
`424`	`424`	`})`
`425`	`425`	`}`
`426`	`426`