Account for java records when checking for unused variables

resolves #2515, resolves #1648 PiperOrigin-RevId: 400246379
google · Oct 1, 2021 · 47da3af · 47da3af
1 parent d4f2198
commit 47da3af
Show file tree

Hide file tree

Showing 2 changed files with 49 additions and 0 deletions.
diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java b/core/src/main/java/com/google/errorprone/bugpatterns/UnusedVariable.java
@@ -610,10 +610,15 @@ private boolean isFieldEligibleForChecking(VariableTree variableTree, VarSymbol
           && ASTHelpers.hasDirectAnnotationWithSimpleName(variableTree, "Inject")) {
         return true;
       }
+      if ((symbol.flags() & RECORD_FLAG) == RECORD_FLAG) {
+        return false;
+      }
       return variableTree.getModifiers().getFlags().contains(Modifier.PRIVATE)
           && !SPECIAL_FIELDS.contains(symbol.getSimpleName().toString());
     }
 
+    private static final long RECORD_FLAG = 1L << 61;
+
     /** Returns whether {@code sym} can be removed without updating call sites in other files. */
     private boolean isParameterSubjectToAnalysis(Symbol sym) {
       checkArgument(sym.getKind() == ElementKind.PARAMETER);

diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/UnusedVariableTest.java
@@ -14,12 +14,15 @@
 
 package com.google.errorprone.bugpatterns;
 
+import static org.junit.Assume.assumeTrue;
+
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.BugCheckerRefactoringTestHelper;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers;
 import com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode;
 import com.google.errorprone.CompilationTestHelper;
 import com.google.errorprone.ErrorProneFlags;
+import com.google.errorprone.util.RuntimeVersion;
 import org.junit.Ignore;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -1353,4 +1356,45 @@ public void unusedReassignment_keepSideEffectsFix() {
         .setFixChooser(FixChoosers.SECOND)
         .doTest();
   }
+
+  @Test
+  public void simpleRecord() {
+    assumeTrue(RuntimeVersion.isAtLeast16());
+    helper
+        .addSourceLines(
+            "SimpleRecord.java", //
+            "public record SimpleRecord (Integer foo, Long bar) {}")
+        .expectNoDiagnostics()
+        .doTest();
+  }
+
+  @Test
+  public void nestedRecord() {
+    assumeTrue(RuntimeVersion.isAtLeast16());
+    helper
+        .addSourceLines(
+            "SimpleClass.java",
+            "public class SimpleClass {",
+            "   public record SimpleRecord (Integer foo, Long bar) {}",
+            "}")
+        .expectNoDiagnostics()
+        .doTest();
+  }
+
+  @Test
+  public void unusedInRecord() {
+    assumeTrue(RuntimeVersion.isAtLeast16());
+    helper
+        .addSourceLines(
+            "SimpleClass.java",
+            "public class SimpleClass {",
+            "  public record SimpleRecord (Integer foo, Long bar) {",
+            "    void f() {",
+            "      // BUG: Diagnostic contains: is never read",
+            "      int x = foo;",
+            "    }",
+            "  }",
+            "}")
+        .doTest();
+  }
 }