[clang][dataflow] Fix bug in Value comparison.

Makes value equivalence require that the values have no properties, except in
the case of equivalence by pointer equality (if the pointers are equal, nothing
else is checked).

Fixes issue #76459.

Author: ymand

clang/lib/Analysis/FlowSensitive/Value.cpp

@@ -27,9 +27,13 @@ static bool areEquivalentIndirectionValues(const Value &Val1,
 }
 
 bool areEquivalentValues(const Value &Val1, const Value &Val2) {
-  return &Val1 == &Val2 || (Val1.getKind() == Val2.getKind() &&
-                            (isa<TopBoolValue>(&Val1) ||
-                             areEquivalentIndirectionValues(Val1, Val2)));
+  // If values are distinct and have properties, we don't consider them equal,
+  // leaving equality up to the user model.
+  return &Val1 == &Val2 ||
+         (Val1.getKind() == Val2.getKind() &&
+          (Val1.properties().empty() && Val2.properties().empty()) &&
+          (isa<TopBoolValue>(&Val1) ||
+           areEquivalentIndirectionValues(Val1, Val2)));
 }
 
 raw_ostream &operator<<(raw_ostream &OS, const Value &Val) {

clang/unittests/Analysis/FlowSensitive/ValueTest.cpp

@@ -53,8 +53,8 @@ TEST(ValueTest, EquivalentValuesWithDifferentPropsEquivalent) {
   TopBoolValue V2(A.makeAtomRef(Atom(3)));
   V1.setProperty("foo", Prop1);
   V2.setProperty("bar", Prop2);
-  EXPECT_TRUE(areEquivalentValues(V1, V2));
-  EXPECT_TRUE(areEquivalentValues(V2, V1));
+  EXPECT_FALSE(areEquivalentValues(V1, V2));
+  EXPECT_FALSE(areEquivalentValues(V2, V1));
 }
 
 TEST(ValueTest, DifferentKindsNotEquivalent) {