fix: let-and-return suggests invalid cast

Author: ErinvanderVeen

clippy_lints/src/returns/let_and_return.rs

@@ -45,7 +45,10 @@ pub(super) fn check_block<'tcx>(cx: &LateContext<'tcx>, block: &'tcx Block<'_>)
                         } else {
                             format!("({src})")
                         }
-                    } else if !cx.typeck_results().expr_adjustments(retexpr).is_empty() {
+                    } else if !cx.typeck_results().expr_adjustments(retexpr).is_empty()
+                        // Do not suggest 'as _' for raw pointers; it's an invalid cast
+                        && !cx.typeck_results().expr_ty_adjusted(retexpr).is_raw_ptr()
+                    {
                         if has_enclosing_paren(&src) {
                             format!("{src} as _")
                         } else {

tests/ui/let_and_return.edition2021.fixed

@@ -271,4 +271,15 @@ fn issue15987() -> i32 {
     r
 }
 
+// https://github.com/rust-lang/rust-clippy/issues/16135
+mod issue16135 {
+    struct S;
+    trait T {}
+    impl T for S {}
+
+    fn f(x: *const S) -> *const dyn T {
+        Clone::clone(&x) as _
+    }
+}
+
 fn main() {}

tests/ui/let_and_return.edition2024.fixed

@@ -271,4 +271,15 @@ fn issue15987() -> i32 {
     r
 }
 
+// https://github.com/rust-lang/rust-clippy/issues/16135
+mod issue16135 {
+    struct S;
+    trait T {}
+    impl T for S {}
+
+    fn f(x: *const S) -> *const dyn T {
+        Clone::clone(&x) as _
+    }
+}
+
 fn main() {}

tests/ui/let_and_return.rs

@@ -271,4 +271,15 @@ fn issue15987() -> i32 {
     r
 }
 
+// https://github.com/rust-lang/rust-clippy/issues/16135
+mod issue16135 {
+    struct S;
+    trait T {}
+    impl T for S {}
+
+    fn f(x: *const S) -> *const dyn T {
+        Clone::clone(&x) as _
+    }
+}
+
 fn main() {}