Improve handling of raw types

* Include the enclosing `TreePath` in the paths returned by `findAllCasts`, `targetType` walks up to find the enclosing method for `return`s
* Check if the instanceof type or the cast type is already non-raw, to avoid adding an extra `<?>`

PiperOrigin-RevId: 737027442

Author: cushon

core/src/main/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceof.java

@@ -41,6 +41,7 @@
 import com.sun.source.tree.ConditionalExpressionTree;
 import com.sun.source.tree.IfTree;
 import com.sun.source.tree.InstanceOfTree;
+import com.sun.source.tree.ParameterizedTypeTree;
 import com.sun.source.tree.ParenthesizedTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.TypeCastTree;
@@ -112,7 +113,7 @@ public Description matchInstanceOf(InstanceOfTree instanceOfTree, VisitorState s
           // anything in scope, but that's effort.
           name = generateVariableName(targetType, state);
         }
-        if (typeArgCount != 0) {
+        if (typeArgCount != 0 && !(instanceOfTree.getType() instanceof ParameterizedTypeTree)) {
           fix.postfixWith(
               instanceOfTree.getType(),
               nCopies(typeArgCount, "?").stream().collect(joining(",", "<", ">")));
@@ -244,7 +245,7 @@ public Void visitTypeCast(TypeCastTree node, Void unused) {
               if (v.equals(symbol)
                   && state.getTypes().isSubtype(targetType, getType(node.getType()))) {
                 usages.add(
-                    getCurrentPath().getParentPath().getLeaf() instanceof ParenthesizedTree p
+                    getCurrentPath().getParentPath().getLeaf() instanceof ParenthesizedTree
                         ? getCurrentPath().getParentPath()
                         : getCurrentPath());
               }
@@ -253,7 +254,7 @@ public Void visitTypeCast(TypeCastTree node, Void unused) {
           }
         };
     for (Tree tree : trees) {
-      scanner.scan(new TreePath(new TreePath(state.getPath().getCompilationUnit()), tree), null);
+      scanner.scan(new TreePath(state.getPath(), tree), null);
     }
     return usages.build();
   }

core/src/test/java/com/google/errorprone/bugpatterns/PatternMatchingInstanceofTest.java

@@ -664,4 +664,38 @@ public String stringify(Object o) {
             """)
         .doTest();
   }
+
+  @Test
+  public void returnTarget() {
+    helper
+        .addInputLines(
+            "Test.java",
+            """
+            class Test<T> {
+              private String val;
+
+              public Class stringify(Object o) {
+                if (o instanceof Class<?>) {
+                  return (Class) o;
+                }
+                return null;
+              }
+            }
+            """)
+        .addOutputLines(
+            "Test.java",
+            """
+            class Test<T> {
+              private String val;
+
+              public Class stringify(Object o) {
+                if (o instanceof Class<?> c) {
+                  return c;
+                }
+                return null;
+              }
+            }
+            """)
+        .doTest(BugCheckerRefactoringTestHelper.TestMode.TEXT_MATCH);
+  }
 }