fix operator resolution to check base classes (#586)

Author: Vipul-Cariappa

lib/Interpreter/CppInterOp.cpp

@@ -3564,7 +3564,21 @@ namespace Cpp {
   void GetOperator(TCppScope_t scope, Operator op,
                    std::vector<TCppFunction_t>& operators, OperatorArity kind) {
     Decl* D = static_cast<Decl*>(scope);
-    if (auto* DC = llvm::dyn_cast_or_null<DeclContext>(D)) {
+    if (auto* CXXRD = llvm::dyn_cast_or_null<CXXRecordDecl>(D)) {
+      auto fn = [&operators, kind, op](const RecordDecl* RD) {
+        ASTContext& C = RD->getASTContext();
+        DeclContextLookupResult Result =
+            RD->lookup(C.DeclarationNames.getCXXOperatorName(
+                (clang::OverloadedOperatorKind)op));
+        for (auto* i : Result) {
+          if (kind & GetOperatorArity(i))
+            operators.push_back(i);
+        }
+        return true;
+      };
+      fn(CXXRD);
+      CXXRD->forallBases(fn);
+    } else if (auto* DC = llvm::dyn_cast_or_null<DeclContext>(D)) {
       ASTContext& C = getSema().getASTContext();
       DeclContextLookupResult Result =
           DC->lookup(C.DeclarationNames.getCXXOperatorName(

unittests/CppInterOp/ScopeReflectionTest.cpp

@@ -1107,4 +1107,30 @@ TEST(ScopeReflectionTest, GetOperator) {
   Cpp::GetOperator(Cpp::GetScope("extra_ops"), Cpp::Operator::OP_Tilde, ops,
                    Cpp::OperatorArity::kBinary);
   EXPECT_EQ(ops.size(), 0);
+
+  std::string inheritance_code = R"(
+  struct Parent {
+    int x;
+    Parent(int x) : x(x) {}
+    Parent operator+(const Parent& other) {
+      return Parent(x + other.x);
+    }
+  };
+
+  struct Child : Parent {
+    Child(int x) : Parent(x) {}
+    Child operator-(const Child& other) {
+      return Child(x - other.x);
+    }
+  };
+  )";
+  Cpp::Declare(inheritance_code.c_str());
+
+  ops.clear();
+  Cpp::GetOperator(Cpp::GetScope("Child"), Cpp::Operator::OP_Plus, ops);
+  EXPECT_EQ(ops.size(), 1);
+
+  ops.clear();
+  Cpp::GetOperator(Cpp::GetScope("Child"), Cpp::Operator::OP_Minus, ops);
+  EXPECT_EQ(ops.size(), 1);
 }