Auto merge of rust-lang#8552 - Jarcho:ptr_arg_8495, r=xFrednet

Don't lint `ptr_arg` on `&mut Cow<_>` fixes: rust-lang#8495 changelog: Don't lint `ptr_arg` on `&mut Cow<_>`
flip1995 · Mar 17, 2022 · 8d5c0ea · 8d5c0ea
2 parents 65e5cd0 + 851e715
commit 8d5c0ea
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diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs
@@ -436,7 +436,7 @@ fn check_fn_args<'cx, 'tcx: 'cx>(
                             DerefTy::Path,
                             None,
                         ),
-                        Some(sym::Cow) => {
+                        Some(sym::Cow) if mutability == Mutability::Not => {
                             let ty_name = name.args
                                 .and_then(|args| {
                                     args.args.iter().find_map(|a| match a {

diff --git a/tests/ui/ptr_arg.rs b/tests/ui/ptr_arg.rs
@@ -194,3 +194,10 @@ fn two_vecs(a: &mut Vec<u32>, b: &mut Vec<u32>) {
     a.push(0);
     b.push(1);
 }
+
+// Issue #8495
+fn cow_conditional_to_mut(a: &mut Cow<str>) {
+    if a.is_empty() {
+        a.to_mut().push_str("foo");
+    }
+}