Fix: JitCall codegen for deleted copy ctor in args

lib/CppInterOp/CppInterOp.cpp

@@ -2568,6 +2568,33 @@
   get_type_as_string(QT, type_name, C, Policy);
 }
 
+static bool IsCopyConstructorDeleted(QualType QT) {
+  CXXRecordDecl* RD = QT->getAsCXXRecordDecl();
+  if (!RD) {
+    // For types that are not C++ records (such as PODs), we assume that they
+    // are copyable, ie their copy constructor is not deleted.
+    return false;
+  }
+
+  RD = RD->getDefinition();
+  assert(RD && "expecting a definition");
+
+  if (RD->hasSimpleCopyConstructor())
+    return false;
+
+  for (auto* Ctor : RD->ctors()) {
+    if (Ctor->isCopyConstructor()) {
+      return Ctor->isDeleted();
+    }
+  }
+
+  assert(0 && "did not find a copy constructor?");
+  // Should never happen and the return value is somewhat arbitrary, but we did
+  // not see a deleted copy ctor. The user will be told if the generated code
+  // doesn't compile.
+  return false;
+}
+
 void make_narg_ctor(const FunctionDecl* FD, const unsigned N,
                     std::ostringstream& typedefbuf, std::ostringstream& callbuf,
                     const std::string& class_name, int indent_level,
@@ -2612,7 +2639,18 @@
       } else if (isPointer) {
         callbuf << "*(" << type_name.c_str() << "**)args[" << i << "]";
       } else {
+        // By-value construction: Figure out if the type can be
+        // copy-constructed. This is tricky and cannot be done in a fully
+        // reliable way, also because std::vector<T> always defines a copy
+        // constructor, even if the type T is only moveable. As a heuristic, we
+        // only check if the copy constructor is deleted, or would be if
+        // implicit.
+        bool Move = IsCopyConstructorDeleted(QT);
+        if (Move)
+          callbuf << "static_cast<" << type_name << "&&>(";
         callbuf << "*(" << type_name.c_str() << "*)args[" << i << "]";
+        if (Move)
+          callbuf << ")";
       }
     }
     callbuf << ")";

unittests/CppInterOp/FunctionReflectionTest.cpp

@@ -2879,6 +2879,33 @@ TYPED_TEST(CPPINTEROP_TEST_MODE, FunctionReflection_FailingTest1) {
   EXPECT_FALSE(Cpp::Declare("int y = x;"));
 }
 
+TYPED_TEST(CPPINTEROP_TEST_MODE, FunctionReflection_DeletedCopyConstrutor) {
+  std::vector<Decl*> Decls;
+  std::vector<Decl*> SubDecls;
+  std::string code = R"(
+        struct GH {
+           int fMember;
+           GH(int m = 1) : fMember(m) {}
+           GH(const GH&) = delete;
+           GH(GH&&) = default;
+        };
+        struct GH_Default {
+           int fMember;
+           GH_Default(GH p = GH()) : fMember(p.fMember) {}
+        };
+      )";
+
+  GetAllTopLevelDecls(code, Decls, false, {"-include", "new"});
+  EXPECT_EQ(Decls.size(), 2);
+
+  GetAllSubDecls(Decls[1], SubDecls);
+  EXPECT_EQ(SubDecls.size(), 3);
+
+  EXPECT_TRUE(Cpp::IsConstructor(SubDecls[2]));
+  auto Fn = Cpp::MakeFunctionCallable(SubDecls[2]);
+  EXPECT_EQ(Fn.getKind(), Cpp::JitCall::kConstructorCall);
+}
+
 TYPED_TEST(CPPINTEROP_TEST_MODE, FunctionReflection_IsExplicit) {
   std::vector<Decl*> Decls;
   std::vector<Decl*> SubDecls;