Make AssignmentExpression matcher parenthesis-invariant on nested assignments

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

@@ -33,6 +33,7 @@
 import com.sun.source.tree.ParenthesizedTree;
 import com.sun.source.tree.Tree;
 import com.sun.source.tree.VariableTree;
+import com.sun.source.util.TreePath;
 import com.sun.tools.javac.code.Symbol.VarSymbol;
 
 /** A BugPattern; see the summary. */
@@ -45,7 +46,17 @@ public final class AssignmentExpression extends BugChecker implements Assignment
 
   @Override
   public Description matchAssignment(AssignmentTree tree, VisitorState state) {
-    Tree parent = state.getPath().getParentPath().getLeaf();
+    TreePath parentPath = state.getPath().getParentPath();
+    // Exempt the C-ism of (foo = getFoo()) != null, etc. before unwrapping parens.
+    if (parentPath.getLeaf() instanceof ParenthesizedTree
+        && parentPath.getParentPath().getLeaf() instanceof BinaryTree) {
+      return Description.NO_MATCH;
+    }
+    // Unwrap ParenthesizedTree for parenthesis-invariant matching.
+    while (parentPath.getLeaf() instanceof ParenthesizedTree) {
+      parentPath = parentPath.getParentPath();
+    }
+    Tree parent = parentPath.getLeaf();
     if (parent instanceof ExpressionStatementTree) {
       return Description.NO_MATCH;
     }
@@ -55,11 +66,6 @@ public Description matchAssignment(AssignmentTree tree, VisitorState state) {
     if (parent instanceof LambdaExpressionTree) {
       return Description.NO_MATCH;
     }
-    // Exempt the C-ism of (foo = getFoo()) != null, etc.
-    if (parent instanceof ParenthesizedTree
-        && state.getPath().getParentPath().getParentPath().getLeaf() instanceof BinaryTree) {
-      return Description.NO_MATCH;
-    }
     // Detect duplicate assignments: a = a = foo() so that we can generate a fix.
     if (isDuplicateAssignment(tree, parent)) {
       return describeMatch(

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

@@ -147,4 +147,22 @@ Object test() {
             """)
         .doTest();
   }
+
+  @Test
+  public void parenthesizedAssignmentInDeclaration() {
+    helper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void test() {
+                int a = 0;
+                int b = 1;
+                // BUG: Diagnostic contains:
+                int k = (a = b);
+              }
+            }
+            """)
+        .doTest();
+  }
 }