MutableConstantField: replace declaration type regardless of the orig…

…inal declaration type.

RELNOTES: Suggest a fix on *any* constant which is initialized with an immutable collection and doesn't use the immutable collection in its declaration type. So "static final Iterable<String> FOO = ImmutableList.of();" will become "static final ImmutableList<String> FOO = ImmutableList.of();".

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=151030307

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

@@ -19,7 +19,7 @@
 import static com.google.errorprone.BugPattern.Category.JDK;
 import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
 
-import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.VisitorState;
 import com.google.errorprone.bugpatterns.BugChecker.VariableTreeMatcher;
@@ -48,54 +48,49 @@
 )
 public final class MutableConstantField extends BugChecker implements VariableTreeMatcher {
 
-  private static final ImmutableMap<String, String> MUTABLE_TO_IMMUTABLE_CLASS_NAME_MAP =
-      ImmutableMap.<String, String>builder()
-          .put("com.google.common.collect.BiMap", "com.google.common.collect.ImmutableBiMap")
-          .put(
-              "com.google.common.collect.ListMultimap",
-              "com.google.common.collect.ImmutableListMultimap")
-          .put("com.google.common.collect.RangeMap", "com.google.common.collect.ImmutableRangeMap")
-          .put("com.google.common.collect.RangeSet", "com.google.common.collect.ImmutableRangeSet")
-          .put(
-              "com.google.common.collect.SetMultimap",
-              "com.google.common.collect.ImmutableSetMultimap")
-          .put(
-              "com.google.common.collect.SortedMultiset",
-              "com.google.common.collect.ImmutableSortedMultiset")
-          .put("com.google.common.collect.Table", "com.google.common.collect.ImmutableTable")
-          .put("java.util.List", "com.google.common.collect.ImmutableList")
-          .put("java.util.Map", "com.google.common.collect.ImmutableMap")
-          .put("java.util.Multimap", "com.google.common.collect.ImmutableMultimap")
-          .put("java.util.Multiset", "com.google.common.collect.ImmutableMultiset")
-          .put("java.util.NavigableMap", "com.google.common.collect.ImmutableSortedMap")
-          .put("java.util.NavigableSet", "com.google.common.collect.ImmutableSortedSet")
-          .put("java.util.Set", "com.google.common.collect.ImmutableSet")
-          .build();
+  private static final ImmutableSet<String> IMMUTABLE_CLASS_NAMES =
+      ImmutableSet.of(
+          "com.google.common.collect.ImmutableBiMap",
+          "com.google.common.collect.ImmutableList",
+          "com.google.common.collect.ImmutableListMultimap",
+          "com.google.common.collect.ImmutableMap",
+          "com.google.common.collect.ImmutableMultimap",
+          "com.google.common.collect.ImmutableMultiset",
+          "com.google.common.collect.ImmutableRangeMap",
+          "com.google.common.collect.ImmutableRangeSet",
+          "com.google.common.collect.ImmutableSet",
+          "com.google.common.collect.ImmutableSetMultimap",
+          "com.google.common.collect.ImmutableSortedMap",
+          "com.google.common.collect.ImmutableSortedMultiset",
+          "com.google.common.collect.ImmutableSortedSet",
+          "com.google.common.collect.ImmutableTable");
 
   @Override
   public Description matchVariable(VariableTree tree, VisitorState state) {
     if (!isConstantField(ASTHelpers.getSymbol(tree))) {
       return Description.NO_MATCH;
     }
 
-    Tree lhsTree = tree.getType();
-    Symbol lhsSymbol = ASTHelpers.getSymbol(lhsTree);
-    if (lhsSymbol == null) {
+    Tree rhsTree = tree.getInitializer();
+    Type rhsType = ASTHelpers.getType(rhsTree);
+    if (rhsType == null) {
       return Description.NO_MATCH;
     }
-    String lhsTypeQualifiedName = lhsSymbol.getQualifiedName().toString();
-    if (!MUTABLE_TO_IMMUTABLE_CLASS_NAME_MAP.containsKey(lhsTypeQualifiedName)) {
+    String rhsTypeQualifiedName = rhsType.tsym.getQualifiedName().toString();
+    if (!IMMUTABLE_CLASS_NAMES.contains(rhsTypeQualifiedName)) {
       return Description.NO_MATCH;
     }
 
-    String immutableClassName = MUTABLE_TO_IMMUTABLE_CLASS_NAME_MAP.get(lhsTypeQualifiedName);
-    Type immutableType = state.getTypeFromString(immutableClassName);
-    Tree rhsTree = tree.getInitializer();
-    Type rhsType = ASTHelpers.getType(rhsTree);
-    if (!ASTHelpers.isSameType(rhsType, immutableType, state)) {
+    Tree lhsTree = tree.getType();
+    Type lhsType = ASTHelpers.getType(lhsTree);
+    if (lhsType == null) {
+      return Description.NO_MATCH;
+    }
+    if (ASTHelpers.isSameType(lhsType, rhsType, state)) {
       return Description.NO_MATCH;
     }
 
+    Type immutableType = state.getTypeFromString(rhsTypeQualifiedName);
     SuggestedFix.Builder fixBuilder = SuggestedFix.builder();
     fixBuilder.replace(
         getTypeTree(lhsTree),

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

@@ -27,6 +27,20 @@ public class MutableConstantFieldTest {
   private final CompilationTestHelper testHelper =
       CompilationTestHelper.newInstance(MutableConstantField.class, getClass());
 
+  @Test
+  public void staticFinalIterableInitializedInDeclarationWithImmutableSetOf_suggestsFix() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            "import com.google.common.collect.ImmutableSet;",
+            "class Test {",
+            "  // BUG: Diagnostic contains: static final ImmutableSet<String> COLORS =",
+            "  static final Iterable<String> COLORS =",
+            "      ImmutableSet.of(\"Red\", \"Green\", \"Blue\");",
+            "}")
+        .doTest();
+  }
+
   @Test
   public void staticFinalSetInitializedInDeclarationWithImmutableSetOf_suggestsFix() {
     testHelper
@@ -103,6 +117,19 @@ public void staticFinalMapInitializedInDeclarationWithImmutableMapOf_suggestsFix
         .doTest();
   }
 
+  @Test
+  public void staticFinalImmutableSetInitializedInDeclarationWithImmutableSet_doesNotSuggestFix() {
+    testHelper
+        .addSourceLines(
+            "Test.java",
+            "import com.google.common.collect.ImmutableSet;",
+            "class Test {",
+            "  static final ImmutableSet<String> COLORS =",
+            "      ImmutableSet.of(\"Red\", \"Green\", \"Blue\");",
+            "}")
+        .doTest();
+  }
+
   @Test
   public void staticFinalSetInitializedInStaticBlock_doesNotSuggestFix() {
     testHelper
@@ -163,9 +190,10 @@ public void mutable_doesNotSuggestFix() {
     testHelper
         .addSourceLines(
             "Test.java",
-            "import com.google.common.collect.ImmutableSet;",
+            "import java.util.ArrayList;",
+            "import java.util.List;",
             "class Test {",
-            "  static final ImmutableSet.Builder<String> MUTABLE = ImmutableSet.builder();",
+            "  static final List<String> MUTABLE = new ArrayList<>();",
             "}")
         .doTest();
   }