resolve static constexpr class attribute

Author: Vipul-Cariappa

lib/Interpreter/CppInterOp.cpp

@@ -1248,6 +1248,18 @@ namespace Cpp {
 
       if (!address)
         address = I.getAddressOfGlobal(GD);
+      if (!address) {
+        if (VD->isConstexpr())
+          Declare((GetQualifiedCompleteName(VD) + ";").c_str());
+        if (VD->hasInit() &&
+            (VD->isConstexpr() || VD->getType().isConstQualified())) {
+          if (const APValue* val = VD->evaluateValue()) {
+            if (VD->getType()->isIntegralType(C)) {
+              return (intptr_t)val->getInt().getRawData();
+            }
+          }
+        }
+      }
       if (!address) {
         auto Linkage = C.GetGVALinkageForVariable(VD);
         // The decl was deferred by CodeGen. Force its emission.

unittests/CppInterOp/FunctionReflectionTest.cpp

@@ -1154,3 +1154,49 @@ TEST(FunctionReflectionTest, Destruct) {
   output = testing::internal::GetCapturedStdout();
   EXPECT_EQ(output, "Destructor Executed");
 }
+
+TEST(FunctionReflectionTest, StaticConstExprDatamember) {
+  if (llvm::sys::RunningOnValgrind())
+    GTEST_SKIP() << "XFAIL due to Valgrind report";
+
+  Cpp::CreateInterpreter();
+
+  Cpp::Declare(R"(
+  class MyClass {
+  public:
+    static constexpr int x = 3;
+  };
+
+  template<int i>
+  class MyTemplatedClass {
+  public:
+    static constexpr int x = i;
+  };
+  )");
+
+  Cpp::TCppScope_t MyClass = Cpp::GetNamed("MyClass");
+  EXPECT_TRUE(MyClass);
+
+  std::vector<Cpp::TCppScope_t> datamembers;
+  Cpp::GetStaticDatamembers(MyClass, datamembers);
+  EXPECT_EQ(datamembers.size(), 1);
+
+  intptr_t offset = Cpp::GetVariableOffset(datamembers[0]);
+  EXPECT_EQ(3, *(int*)offset);
+
+  ASTContext& C = Interp->getCI()->getASTContext();
+  std::vector<Cpp::TemplateArgInfo> template_args = {
+      {C.IntTy.getAsOpaquePtr(), "5"}};
+
+  Cpp::TCppFunction_t MyTemplatedClass =
+      Cpp::InstantiateTemplate(Cpp::GetNamed("MyTemplatedClass"),
+                               template_args.data(), template_args.size());
+  EXPECT_TRUE(MyTemplatedClass);
+
+  datamembers.clear();
+  Cpp::GetStaticDatamembers(MyTemplatedClass, datamembers);
+  EXPECT_EQ(datamembers.size(), 1);
+
+  offset = Cpp::GetVariableOffset(datamembers[0]);
+  EXPECT_EQ(5, *(int*)offset);
+}