Extend map_clone lint to also work on non-explicit closures

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;
 

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()
  })
 }
 

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();

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();

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