add NegativeBoolean check

Limited to local variables beginning with 'no' or 'not', and only flag on changed lines.

Local run on //java/com/google/common: unknown commit
Flume run: unknown commit

PiperOrigin-RevId: 707232893

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

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2024 The Error Prone Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
+import static com.google.errorprone.util.ASTHelpers.getSymbol;
+
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.sun.source.tree.VariableTree;
+import com.sun.tools.javac.code.Symbol;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.type.TypeKind;
+
+/** Discourages the use of negative boolean names. */
+@BugPattern(summary = "Prefer positive boolean names", severity = WARNING)
+public final class NegativeBoolean extends BugChecker implements VariableTreeMatcher {
+
+  // Match names beginning with 'no' or 'not'
+  private static final Pattern NEGATIVE_NAME = Pattern.compile("^not?[A-Z].*$");
+
+  @Override
+  public Description matchVariable(VariableTree node, VisitorState state) {
+    // Only consider local variables of type boolean
+    Symbol symbol = getSymbol(node);
+    if (!symbol.getKind().equals(ElementKind.LOCAL_VARIABLE)) {
+      return Description.NO_MATCH;
+    }
+    if (!symbol.asType().getKind().equals(TypeKind.BOOLEAN)) {
+      return Description.NO_MATCH;
+    }
+
+    if (isNegativeName(symbol.getSimpleName().toString())) {
+      return describeMatch(node);
+    }
+    return Description.NO_MATCH;
+  }
+
+  private static boolean isNegativeName(String name) {
+    Matcher m = NEGATIVE_NAME.matcher(name);
+    return m.matches();
+  }
+}

core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java

@@ -271,6 +271,7 @@
 import com.google.errorprone.bugpatterns.NamedLikeContextualKeyword;
 import com.google.errorprone.bugpatterns.NarrowCalculation;
 import com.google.errorprone.bugpatterns.NarrowingCompoundAssignment;
+import com.google.errorprone.bugpatterns.NegativeBoolean;
 import com.google.errorprone.bugpatterns.NegativeCharLiteral;
 import com.google.errorprone.bugpatterns.NestedInstanceOfConditions;
 import com.google.errorprone.bugpatterns.NewFileSystem;
@@ -1216,6 +1217,7 @@ public static ScannerSupplier warningChecks() {
           MultiVariableDeclaration.class,
           MultipleTopLevelClasses.class,
           MutableGuiceModule.class,
+          NegativeBoolean.class,
           NoAllocationChecker.class,
           NonCanonicalStaticMemberImport.class,
           NonFinalStaticField.class, // Intentionally disabled in OSS.

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

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2024 The Error Prone Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class NegativeBooleanTest {
+
+  private final CompilationTestHelper testHelper =
+      CompilationTestHelper.newInstance(NegativeBoolean.class, getClass());
+
+  @Test
+  public void prefix_no_isFlagged() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void foo() {
+                // BUG: Diagnostic contains: Prefer positive
+                boolean noBar;
+              }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void prefix_not_isFlagged() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void foo() {
+                // BUG: Diagnostic contains: Prefer positive
+                boolean notBar;
+              }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void prefix_notable_isNotFlagged() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void foo() {
+                boolean notableBar;
+              }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void integer_isNotFlagged() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void foo() {
+                int notBar;
+              }
+            }
+            """)
+        .doTest();
+  }
+
+  @Test
+  public void parameter_isNotFlagged() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            """
+            class Test {
+              void foo(boolean notBar) {
+                return;
+              }
+            }
+            """)
+        .doTest();
+  }
+}