Don't lint exlipicit_auto_deref when other adjustments are needed

Author: Jarcho

clippy_lints/src/dereference.rs

@@ -357,7 +357,11 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
                                 }),
                                 StateData { span: expr.span, hir_id: expr.hir_id, position },
                             ));
-                        } else if position.is_deref_stable() {
+                        } else if position.is_deref_stable()
+                            // Auto-deref doesn't combine with other adjustments
+                            && next_adjust.map_or(true, |a| matches!(a.kind, Adjust::Deref(_) | Adjust::Borrow(_)))
+                            && iter.all(|a| matches!(a.kind, Adjust::Deref(_) | Adjust::Borrow(_)))
+                        {
                             self.state = Some((
                                 State::Borrow { mutability },
                                 StateData {

tests/ui/explicit_auto_deref.fixed

@@ -242,4 +242,17 @@ fn main() {
     fn ret_any(x: &Box<dyn std::any::Any>) -> &dyn std::any::Any {
         &**x
     }
+
+    let x = String::new();
+    let _: *const str = &*x;
+
+    struct S7([u32; 1]);
+    impl core::ops::Deref for S7 {
+        type Target = [u32; 1];
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+    let x = S7([0]);
+    let _: &[u32] = &*x;
 }

tests/ui/explicit_auto_deref.rs

@@ -242,4 +242,17 @@ fn main() {
     fn ret_any(x: &Box<dyn std::any::Any>) -> &dyn std::any::Any {
         &**x
     }
+
+    let x = String::new();
+    let _: *const str = &*x;
+
+    struct S7([u32; 1]);
+    impl core::ops::Deref for S7 {
+        type Target = [u32; 1];
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+    let x = S7([0]);
+    let _: &[u32] = &*x;
 }