Yet another JUnitIncompatibleType crash fix.

Fixes external #4377.

PiperOrigin-RevId: 638595224

Author: graememorgan

core/src/main/java/com/google/errorprone/bugpatterns/collectionincompatibletype/JUnitIncompatibleType.java

@@ -23,6 +23,7 @@
 import static com.google.errorprone.matchers.Matchers.anyOf;
 import static com.google.errorprone.matchers.method.MethodMatchers.staticMethod;
 import static com.google.errorprone.util.ASTHelpers.getSymbol;
+import static com.google.errorprone.util.ASTHelpers.getUpperBound;
 import static com.google.errorprone.util.ASTHelpers.isSameType;
 
 import com.google.errorprone.BugPattern;
@@ -79,10 +80,15 @@ public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState
       var typeB = ignoringCasts(arguments.get(skip + 1), state);
       return checkCompatibility(tree, typeA, typeB, state);
     } else if (ASSERT_ARRAY_EQUALS.matches(tree, state)) {
+
       int skip = argumentsToSkip(tree, state);
-      var typeA = ((ArrayType) ignoringCasts(arguments.get(skip), state)).elemtype;
-      var typeB = ((ArrayType) ignoringCasts(arguments.get(skip + 1), state)).elemtype;
-      return checkCompatibility(tree, typeA, typeB, state);
+      var expected = getUpperBound(ignoringCasts(arguments.get(skip), state), state.getTypes());
+      var actual = getUpperBound(ignoringCasts(arguments.get(skip + 1), state), state.getTypes());
+      if (!(expected instanceof ArrayType) || !(actual instanceof ArrayType)) {
+        return NO_MATCH;
+      }
+      return checkCompatibility(
+          tree, ((ArrayType) expected).elemtype, ((ArrayType) actual).elemtype, state);
     }
     return NO_MATCH;
   }

core/src/test/java/com/google/errorprone/bugpatterns/collectionincompatibletype/JUnitIncompatibleTypeTest.java

@@ -144,4 +144,51 @@ public void fourArgumentOverload() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void arrayNullComparison() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import static org.junit.Assert.assertArrayEquals;",
+            "class Test {",
+            "  public void test() {",
+            "    assertArrayEquals(null, new Object[] {2});",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void typeVariables_incompatible() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import static org.junit.Assert.assertArrayEquals;",
+            "import java.util.Map;",
+            "class Test {",
+            "  public <T extends String> void test(Map<Integer, T[]> xs) {",
+            "    T[] x = xs.get(1);",
+            "    // BUG: Diagnostic contains:",
+            "    assertArrayEquals(x, new Double[] {1d});",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void typeVariables_compatible() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import static org.junit.Assert.assertArrayEquals;",
+            "import java.util.Map;",
+            "class Test {",
+            "  public <T extends Double> void test(Map<Integer, T[]> xs) {",
+            "    T[] x = xs.get(1);",
+            "    assertArrayEquals(x, new Double[] {1d});",
+            "  }",
+            "}")
+        .doTest();
+  }
 }