also lint .as_mut().cloned()

clippy_lints/src/methods/mod.rs

@@ -3832,10 +3832,10 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for usage of `.as_ref().cloned()` on `Option`s
+    /// Checks for usage of `.as_ref().cloned()` and `.as_mut().cloned()` on `Option`s
     ///
     /// ### Why is this bad?
-    /// This can be written more concisely by cloning the option directly.
+    /// This can be written more concisely by cloning the `Option` directly.
     ///
     /// ### Example
     /// ```no_run
@@ -4259,8 +4259,8 @@ impl Methods {
                 ("assume_init", []) => uninit_assumed_init::check(cx, expr, recv),
                 ("cloned", []) => {
                     cloned_instead_of_copied::check(cx, expr, recv, span, &self.msrv);
-                    if let Some(("as_ref", recv, .., as_ref_ident_span)) = method_call(recv) {
-                        option_as_ref_cloned::check(cx, recv, as_ref_ident_span, span);
+                    if let Some((name @ ("as_ref" | "as_mut"), recv, .., as_ref_ident_span)) = method_call(recv) {
+                        option_as_ref_cloned::check(cx, recv, as_ref_ident_span, span, name);
                     }
                 },
                 ("collect", []) if is_trait_method(cx, expr, sym::Iterator) => {

clippy_lints/src/methods/option_as_ref_cloned.rs

@@ -7,13 +7,19 @@ use rustc_span::{sym, Span};
 
 use super::OPTION_AS_REF_CLONED;
 
-pub(super) fn check(cx: &LateContext<'_>, as_ref_recv: &Expr<'_>, as_ref_ident_span: Span, cloned_span: Span) {
+pub(super) fn check(
+    cx: &LateContext<'_>,
+    as_ref_recv: &Expr<'_>,
+    as_ref_ident_span: Span,
+    cloned_ident_span: Span,
+    method_name: &str,
+) {
     if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(as_ref_recv).peel_refs(), sym::Option) {
         span_lint_and_sugg(
             cx,
             OPTION_AS_REF_CLONED,
-            as_ref_ident_span.to(cloned_span),
-            "cloning an `Option<_>` using `.as_ref().cloned()`",
+            as_ref_ident_span.to(cloned_ident_span),
+            &format!("cloning an `Option<_>` using `.{method_name}().cloned()`"),
             "this can be written more concisely by cloning the `Option<_>` directly",
             "clone".into(),
             Applicability::MachineApplicable,

tests/ui/option_as_ref_cloned.fixed

@@ -2,7 +2,7 @@
 #![allow(clippy::clone_on_copy)]
 
 fn main() {
-    let x = Some(String::new());
+    let mut x = Some(String::new());
 
     let _: Option<String> = x.clone();
     let _: Option<String> = x.clone();

tests/ui/option_as_ref_cloned.rs

@@ -2,10 +2,10 @@
 #![allow(clippy::clone_on_copy)]
 
 fn main() {
-    let x = Some(String::new());
+    let mut x = Some(String::new());
 
     let _: Option<String> = x.as_ref().cloned();
-    let _: Option<String> = x.as_ref().cloned();
+    let _: Option<String> = x.as_mut().cloned();
 
     let y = x.as_ref();
     let _: Option<&String> = y.as_ref().cloned();

tests/ui/option_as_ref_cloned.stderr

@@ -11,10 +11,10 @@ help: this can be written more concisely by cloning the `Option<_>` directly
 LL |     let _: Option<String> = x.clone();
    |                               ~~~~~
 
-error: cloning an `Option<_>` using `.as_ref().cloned()`
+error: cloning an `Option<_>` using `.as_mut().cloned()`
   --> $DIR/option_as_ref_cloned.rs:8:31
    |
-LL |     let _: Option<String> = x.as_ref().cloned();
+LL |     let _: Option<String> = x.as_mut().cloned();
    |                               ^^^^^^^^^^^^^^^
    |
 help: this can be written more concisely by cloning the `Option<_>` directly