Suppress FieldCanBeLocal based on unused prefices.

graememorgan · Error Prone Team · commit 4a5fd7bd5a1f · 2022-12-21T12:52:33.000-08:00
PiperOrigin-RevId: 496985585
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/FieldCanBeLocal.java b/core/src/main/java/com/google/errorprone/bugpatterns/FieldCanBeLocal.java
@@ -86,7 +86,8 @@ public Void visitVariable(VariableTree variableTree, Void unused) {
         if (symbol.getKind() == ElementKind.FIELD
             && symbol.isPrivate()
             && canBeLocal(variableTree)
-            && !shouldKeep(variableTree)) {
+            && !shouldKeep(variableTree)
+            && !symbol.getSimpleName().toString().startsWith("unused")) {
           potentialFields.put(symbol, getCurrentPath());
         }
         return null;
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/FieldCanBeLocalTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/FieldCanBeLocalTest.java
@@ -48,6 +48,21 @@ public void simplePositive() {
         .doTest();
   }
 
+  @Test
+  public void suppressedByUnusedPrefix() {
+    helper
+        .addSourceLines(
+            "Test.java",
+            "class Test {",
+            "  private int unusedA;",
+            "  int foo() {",
+            "    unusedA = 1;",
+            "    return unusedA;",
+            "  }",
+            "}")
+        .doTest();
+  }
+
   @Test
   public void multipleAssignments() {
     refactoringTestHelper
