handle forward declarations of classes when retrieving methods (#688)

Author: Vipul-Cariappa

lib/CppInterOp/CppInterOp.cpp

@@ -615,7 +615,9 @@ static Decl* GetScopeFromType(QualType QT) {
     Type = Type->getUnqualifiedDesugaredType();
     if (auto* ET = llvm::dyn_cast<EnumType>(Type))
       return ET->getDecl();
-    return Type->getAsCXXRecordDecl();
+    CXXRecordDecl* CXXRD = Type->getAsCXXRecordDecl();
+    if (CXXRD)
+      return CXXRD->getCanonicalDecl();
   }
   return 0;
 }
@@ -634,7 +636,7 @@ static clang::Decl* GetUnderlyingScope(clang::Decl* D) {
       D = Scope;
   }
 
-  return D;
+  return D->getCanonicalDecl();
 }
 
 TCppScope_t GetUnderlyingScope(TCppScope_t scope) {
@@ -843,6 +845,8 @@ static void GetClassDecls(TCppScope_t klass,
 #ifdef CPPINTEROP_USE_CLING
   cling::Interpreter::PushTransactionRAII RAII(&getInterp());
 #endif // CPPINTEROP_USE_CLING
+  if (CXXRD->hasDefinition())
+    CXXRD = CXXRD->getDefinition();
   getSema().ForceDeclarationOfImplicitMembers(CXXRD);
   for (Decl* DI : CXXRD->decls()) {
     if (auto* MD = dyn_cast<DeclType>(DI))

unittests/CppInterOp/FunctionReflectionTest.cpp

@@ -22,6 +22,8 @@ using namespace clang;
 TEST(FunctionReflectionTest, GetClassMethods) {
   std::vector<Decl*> Decls;
   std::string code = R"(
+    class A;
+
     class A {
     public:
       int f1(int a, int b) { return a + b; }
@@ -70,7 +72,7 @@ TEST(FunctionReflectionTest, GetClassMethods) {
   EXPECT_EQ(get_method_name(methods0[10]), "inline A::~A()");
 
   std::vector<Cpp::TCppFunction_t> methods1;
-  Cpp::GetClassMethods(Decls[1], methods1);
+  Cpp::GetClassMethods(Decls[2], methods1);
   EXPECT_EQ(methods0.size(), methods1.size());
   EXPECT_EQ(methods0[0], methods1[0]);
   EXPECT_EQ(methods0[1], methods1[1]);
@@ -79,7 +81,7 @@ TEST(FunctionReflectionTest, GetClassMethods) {
   EXPECT_EQ(methods0[4], methods1[4]);
 
   std::vector<Cpp::TCppFunction_t> methods2;
-  Cpp::GetClassMethods(Decls[2], methods2);
+  Cpp::GetClassMethods(Decls[3], methods2);
 
   EXPECT_EQ(methods2.size(), 6);
   EXPECT_EQ(get_method_name(methods2[0]), "B::B(int n)");
@@ -90,7 +92,7 @@ TEST(FunctionReflectionTest, GetClassMethods) {
   EXPECT_EQ(get_method_name(methods2[5]), "inline B &B::operator=(B &&)");
 
   std::vector<Cpp::TCppFunction_t> methods3;
-  Cpp::GetClassMethods(Decls[3], methods3);
+  Cpp::GetClassMethods(Decls[4], methods3);
 
   EXPECT_EQ(methods3.size(), 9);
   EXPECT_EQ(get_method_name(methods3[0]), "B::B(int n)");
@@ -104,7 +106,7 @@ TEST(FunctionReflectionTest, GetClassMethods) {
 
   // Should not crash.
   std::vector<Cpp::TCppFunction_t> methods4;
-  Cpp::GetClassMethods(Decls[4], methods4);
+  Cpp::GetClassMethods(Decls[5], methods4);
   EXPECT_EQ(methods4.size(), 0);
 
   std::vector<Cpp::TCppFunction_t> methods5;