From 0df6e1fe7cd0cb919a128f984d1587577d72ead6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89amonn=20McManus?= <emcmanus@google.com>
Date: Tue, 1 Sep 2026 10:29:04 -0700
Subject: [PATCH] Undo a change that disabled part of a check.

We had to disable the check that catches, for example, `messageLite.getExtension(Foo.class) != null`. (It is never null.) Some Google code was broken by the new check. That code has now been updated.

PiperOrigin-RevId: 974572697
---
 .../bugpatterns/ImpossibleNullComparison.java | 27 +-----------
 .../ImpossibleNullComparisonTest.java         | 44 -------------------
 2 files changed, 2 insertions(+), 69 deletions(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/ImpossibleNullComparison.java b/core/src/main/java/com/google/errorprone/bugpatterns/ImpossibleNullComparison.java
index 929a217f0c9..0caece85abc 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/ImpossibleNullComparison.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/ImpossibleNullComparison.java
@@ -122,33 +122,12 @@ public final class ImpossibleNullComparison extends BugChecker
   private static final ImmutableSet<Kind> COMPARISON_OPERATORS =
       Sets.immutableEnumSet(Kind.EQUAL_TO, Kind.NOT_EQUAL_TO);
 
-  private static final Matcher<ExpressionTree> EXTENSION_METHODS_WITH_FIX_LEGACY =
-      instanceMethod()
-          .onDescendantOf(EXTENDABLE_MESSAGE_CLASS)
-          .named("getExtension")
-          .withParameters(EXTENSION_LITE_CLASS);
-
   private static final Matcher<ExpressionTree> EXTENSION_METHODS_WITH_FIX =
       instanceMethod()
           .onDescendantOfAny(EXTENDABLE_MESSAGE_CLASS, EXTENDABLE_MESSAGE_LITE_CLASS)
           .named("getExtension")
           .withParameters(EXTENSION_LITE_CLASS);
 
-  private static final Matcher<ExpressionTree> EXTENSION_METHODS_WITH_NO_FIX_LEGACY =
-      anyOf(
-          instanceMethod()
-              .onDescendantOf(MESSAGE_OR_BUILDER_CLASS)
-              .named("getRepeatedField")
-              .withParameters(FIELD_DESCRIPTOR_CLASS, "int"),
-          instanceMethod()
-              .onDescendantOf(EXTENDABLE_MESSAGE_CLASS)
-              .named("getExtension")
-              .withParameters(EXTENSION_LITE_CLASS, "int"),
-          instanceMethod()
-              .onDescendantOf(MESSAGE_OR_BUILDER_CLASS)
-              .named("getField")
-              .withParameters(FIELD_DESCRIPTOR_CLASS));
-
   private static final Matcher<ExpressionTree> EXTENSION_METHODS_WITH_NO_FIX =
       anyOf(
           instanceMethod()
@@ -593,12 +572,10 @@ private String generateFix(
         if (!protoReceiver(checkOrBuilder).matches(tree, state)) {
           return null;
         }
-        if ((checkOrBuilder ? EXTENSION_METHODS_WITH_NO_FIX : EXTENSION_METHODS_WITH_NO_FIX_LEGACY)
-            .matches(tree, state)) {
+        if (EXTENSION_METHODS_WITH_NO_FIX.matches(tree, state)) {
           return GetterTypes::emptyFix;
         }
-        if ((checkOrBuilder ? EXTENSION_METHODS_WITH_FIX : EXTENSION_METHODS_WITH_FIX_LEGACY)
-            .matches(tree, state)) {
+        if (EXTENSION_METHODS_WITH_FIX.matches(tree, state)) {
           // If the extension represents a repeated field (i.e.: it's an ExtensionLite<T, List<R>>),
           // the suggested fix from get->has isn't appropriate,so we shouldn't suggest a replacement
 
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/ImpossibleNullComparisonTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/ImpossibleNullComparisonTest.java
index b4fa6fad017..80ed912d692 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/ImpossibleNullComparisonTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/ImpossibleNullComparisonTest.java
@@ -689,48 +689,4 @@ public void test(TestProtoMessageOrBuilder orBld) {
             """)
         .doTest();
   }
-
-  @Test
-  public void liteExtendableMessage_flagEnabled() {
-    compilationHelper
-        .addSourceLines(
-            "Test.java",
-            """
-            import com.google.protobuf.ExtensionLite;
-            import com.google.protobuf.GeneratedMessageLite;
-
-            public class Test {
-              public static <MessageType extends GeneratedMessageLite.ExtendableMessage<MessageType, ?>, Type>
-                  void test(
-                      GeneratedMessageLite.ExtendableMessage<MessageType, ?> msg,
-                      ExtensionLite<MessageType, Type> extension) {
-                // BUG: Diagnostic contains: msg.hasExtension(extension)
-                if (msg.getExtension(extension) != null) {}
-              }
-            }
-            """)
-        .doTest();
-  }
-
-  @Test
-  public void liteExtendableMessage_flagDisabled() {
-    compilationHelper
-        .setArgs("-XepOpt:ImpossibleNullComparison:CheckOrBuilder=false")
-        .addSourceLines(
-            "Test.java",
-            """
-            import com.google.protobuf.ExtensionLite;
-            import com.google.protobuf.GeneratedMessageLite;
-
-            public class Test {
-              public static <MessageType extends GeneratedMessageLite.ExtendableMessage<MessageType, ?>, Type>
-                  void test(
-                      GeneratedMessageLite.ExtendableMessage<MessageType, ?> msg,
-                      ExtensionLite<MessageType, Type> extension) {
-                if (msg.getExtension(extension) != null) {}
-              }
-            }
-            """)
-        .doTest();
-  }
 }