Match on more types in ReferenceEquality

PiperOrigin-RevId: 921575366

Author: cushon

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

@@ -22,18 +22,15 @@
 import com.google.errorprone.BugPattern;
 import com.google.errorprone.BugPattern.StandardTags;
 import com.google.errorprone.VisitorState;
-import com.google.errorprone.suppliers.Supplier;
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ClassTree;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.LambdaExpressionTree;
 import com.sun.source.tree.MethodTree;
-import com.sun.tools.javac.code.Scope;
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Symbol.MethodSymbol;
 import com.sun.tools.javac.code.Symtab;
 import com.sun.tools.javac.code.Type;
-import com.sun.tools.javac.util.Name;
 
 /** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
 @BugPattern(
@@ -65,9 +62,6 @@ protected boolean matchArgument(ExpressionTree tree, VisitorState state) {
     if (ASTHelpers.isSubtype(type, state.getSymtab().classType, state)) {
       return false;
     }
-    if (!implementsEquals(type, state)) {
-      return false;
-    }
     return true;
   }
 
@@ -113,28 +107,4 @@ private static boolean overridesMethodOnType(
   private static Symbol getOnlyMember(VisitorState state, Type type, String name) {
     return getOnlyElement(type.tsym.members().getSymbolsByName(state.getName(name)));
   }
-
-  /** Check if the method declares or inherits an implementation of .equals() */
-  public static boolean implementsEquals(Type type, VisitorState state) {
-    Name equalsName = EQUALS.get(state);
-    Symbol objectEquals = getOnlyMember(state, state.getSymtab().objectType, "equals");
-    for (Type sup : state.getTypes().closure(type)) {
-      if (ASTHelpers.isSameType(sup, state.getSymtab().objectType, state)) {
-        continue;
-      }
-      Scope scope = sup.tsym.members();
-      if (scope == null) {
-        continue;
-      }
-      for (Symbol sym : scope.getSymbolsByName(equalsName)) {
-        if (sym.overrides(objectEquals, type.tsym, state.getTypes(), /* checkResult= */ false)) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-
-  private static final Supplier<Name> EQUALS =
-      VisitorState.memoize(state -> state.getName("equals"));
 }

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

@@ -54,7 +54,7 @@ void something(TestProtoMessage f1, TestProtoMessage f2) {
   }
 
   @Test
-  public void negative_const() {
+  public void positive_const() {
     compilationHelper
         .addSourceLines(
             "Foo.java",
@@ -70,10 +70,12 @@ class Test {
               public static final Foo CONST = new Foo();
 
               boolean f(Foo a) {
+                // BUG: Diagnostic contains:
                 return a == CONST;
               }
 
               boolean f(Object o, Foo a) {
+                // BUG: Diagnostic contains:
                 return o == a;
               }
             }
@@ -82,7 +84,7 @@ boolean f(Object o, Foo a) {
   }
 
   @Test
-  public void negative_extends_equalsObject() {
+  public void extends_equalsObject() {
     compilationHelper
         .addSourceLines(
             "Sup.java",
@@ -100,6 +102,7 @@ public boolean equals(Object o) {
 
             class Test extends Sup {
               boolean f(Object a, Test b) {
+                // BUG: Diagnostic contains: a.equals(b)
                 return a == b;
               }
             }
@@ -158,7 +161,7 @@ boolean f(Test a, Test b) {
   }
 
   @Test
-  public void negative_noEquals() {
+  public void positive_noEquals() {
     compilationHelper
         .addSourceLines(
             "Test.java",
@@ -167,6 +170,7 @@ public void negative_noEquals() {
 
             class Test {
               boolean f(Test a, Test b) {
+                // BUG: Diagnostic contains: a.equals(b)
                 return a == b;
               }
             }
@@ -363,6 +367,7 @@ interface Sup {
 
             class Test implements Sup {
               boolean f(Object a, Test b) {
+                // BUG: Diagnostic contains: a.equals(b)
                 return a == b;
               }
             }
@@ -434,13 +439,17 @@ public void erroneous() {
     compilationHelper
         .addSourceLines(
             "Test.java",
-            "import " + MayImplementEquals.class.getCanonicalName() + ";",
-            "abstract class Test {",
-            "  abstract MayImplementEquals getter();",
-            "  boolean f(MayImplementEquals b) {",
-            "    return getter() == b;",
-            "  }",
-            "}")
+            """
+            import %s;
+            abstract class Test {
+              abstract MayImplementEquals getter();
+              boolean f(MayImplementEquals b) {
+                // BUG: Diagnostic contains: getter().equals(b)
+                return getter() == b;
+              }
+            }
+            """
+                .formatted(MayImplementEquals.class.getCanonicalName()))
         .withClasspath(MayImplementEquals.class, ReferenceEqualityTest.class)
         .doTest();
   }
@@ -463,6 +472,7 @@ boolean g(T t1, T t2) {
               }
 
               boolean g(X x1, X x2) {
+                // BUG: Diagnostic contains:
                 return x1 == x2;
               }
             }