Fix reference mutability in coerce_container_to_any diagnostics

Author: Ralith

clippy_lints/src/coerce_container_to_any.rs

@@ -79,15 +79,18 @@ impl<'tcx> LateLintPass<'tcx> for CoerceContainerToAny {
             ExprKind::AddrOf(_, _, referent) => (referent, depth),
             _ => (e, depth + 1),
         };
+        let ty::Ref(_, _, mutability) = *cx.typeck_results().expr_ty_adjusted(e).kind() else {
+            return;
+        };
         let sugg = sugg::make_unop(
-            &format!("&{}", str::repeat("*", deref_count)),
+            &format!("{}{}", mutability.ref_prefix_str(), str::repeat("*", deref_count)),
             Sugg::hir(cx, target_expr, ".."),
         );
         span_lint_and_sugg(
             cx,
             COERCE_CONTAINER_TO_ANY,
             e.span,
-            format!("coercing `{expr_ty}` to `&dyn Any`"),
+            format!("coercing `{expr_ty}` to `{}dyn Any`", mutability.ref_prefix_str()),
             "consider dereferencing",
             sugg.to_string(),
             Applicability::MaybeIncorrect,

tests/ui/coerce_container_to_any.fixed

@@ -3,7 +3,7 @@
 use std::any::Any;
 
 fn main() {
-    let x: Box<dyn Any> = Box::new(());
+    let mut x: Box<dyn Any> = Box::new(());
     let ref_x = &x;
 
     f(&*x);
@@ -15,9 +15,16 @@ fn main() {
     let _: &dyn Any = &*x;
     //~^ coerce_container_to_any
 
+    let _: &dyn Any = &*x;
+    //~^ coerce_container_to_any
+
+    let _: &mut dyn Any = &mut *x;
+    //~^ coerce_container_to_any
+
     f(&42);
     f(&Box::new(()));
     f(&Box::new(Box::new(())));
+    let ref_x = &x;
     f(&**ref_x);
     f(&*x);
     let _: &dyn Any = &*x;

tests/ui/coerce_container_to_any.rs

@@ -3,7 +3,7 @@
 use std::any::Any;
 
 fn main() {
-    let x: Box<dyn Any> = Box::new(());
+    let mut x: Box<dyn Any> = Box::new(());
     let ref_x = &x;
 
     f(&x);
@@ -15,9 +15,16 @@ fn main() {
     let _: &dyn Any = &x;
     //~^ coerce_container_to_any
 
+    let _: &dyn Any = &mut x;
+    //~^ coerce_container_to_any
+
+    let _: &mut dyn Any = &mut x;
+    //~^ coerce_container_to_any
+
     f(&42);
     f(&Box::new(()));
     f(&Box::new(Box::new(())));
+    let ref_x = &x;
     f(&**ref_x);
     f(&*x);
     let _: &dyn Any = &*x;

tests/ui/coerce_container_to_any.stderr

@@ -19,5 +19,17 @@ error: coercing `&std::boxed::Box<dyn std::any::Any>` to `&dyn Any`
 LL |     let _: &dyn Any = &x;
    |                       ^^ help: consider dereferencing: `&*x`
 
-error: aborting due to 3 previous errors
+error: coercing `&mut std::boxed::Box<dyn std::any::Any>` to `&dyn Any`
+  --> tests/ui/coerce_container_to_any.rs:18:23
+   |
+LL |     let _: &dyn Any = &mut x;
+   |                       ^^^^^^ help: consider dereferencing: `&*x`
+
+error: coercing `&mut std::boxed::Box<dyn std::any::Any>` to `&mut dyn Any`
+  --> tests/ui/coerce_container_to_any.rs:21:27
+   |
+LL |     let _: &mut dyn Any = &mut x;
+   |                           ^^^^^^ help: consider dereferencing: `&mut *x`
+
+error: aborting due to 5 previous errors