Visual Studio Intellisense not working when inheriting from template class

Question

Here is a testing snippet involving inheriting from template classes:

#include <iostream>
using namespace std;

template <typename T>
struct A {
    T x;
};

template <typename T>
struct B : public A<T> {
    B(T x, T y) : A<T>{ x }, y{ y } { }
    T y;
};

template <typename T>
struct C : public B<T> {
    C(T x, T y, T z) : B<T>{ x, y }, z{ z } { }
    T z;

    // when I typed `this->`, Intellisense didn't give me the option `x`,
    // which is iherited from `A<T>` and should appear in the autocomplete pop-up.
    // In contrast, `this->` did give the option `y`.
    void test() { cout << this->x << ", " << this->y << ", " << z << endl; }
};

int main() {
    C<int> c{ 1, 2, 3 };
    c.test();  // prints out `1, 2, 3` as expected
    return 0;
}

The code compiles and runs. But in void C<T>::test(), when I tried to access the member x defined in the indirect base class A<T> using this pointer, x didn't show up in the Intellisense autocomplete pop-up. On the other hand, the directly inherited member y did show-up.

I tested with VS2019 and VSCode+gcc, both of which gave similar results.

But I know that Intellisense is a very powerful engine, so I wonder if I'm doing inheritance from template classes correctly or not? If I'm wrong, what is the proper way?

Intellisense is not as accurate as the compiler proper. It can (and does) make mistakes. — Paul Sanders, Nov 10 '20 at 07:43
@rioV8 x is not a dependent name in the context of a class template, see [Why do I have to access template base class members through the this pointer?](https://stackoverflow.com/questions/4643074/why-do-i-have-to-access-template-base-class-members-through-the-this-pointer) — Leon Cruz, Nov 10 '20 at 11:33

score 1 · Accepted Answer · answered Nov 10 '20 at 09:46

I also get the same situation in my side. And I think it is a real issue of C++ Intellisense rather than C++ syntax standard.

In fact, the project builds and runs well and can print the value of x without any errors, which proves that the issue is not related to C++ syntax standard.

And it is just a pure C++ IntelliSense problem. And Intellisense cannot get the member from the second-level struct.

I have reported the issue on our DC Forum. And you can vote it and add any comments if I did not describe the issue in detail so that it will get more Microsoft's attention. And I hope the Team will give you a satisfactory reply.

Suggestion

Since the process might take a long time, as a suggestion, so far, you could also let struct C inherit A. And Intellisense cannot get the member from the A(a second-level struct) so far.

template <typename T>
struct C : public B<T>, public A<T> {
    C(T x, T y, T z) : B<T>{ x, y }, z{ z } { }
    T z;

    // when I typed `this->`, Intellisense didn't give me the option `x`,
    // which is iherited from `A<T>` and should appear in the autocomplete pop-up.
    // In contrast, `this->` did give the option `y`.
    void test() { cout <<this->x << ", " << this->y << ", " << z << endl; }
};

Thanks for the suggestion. But I think adding A as another base just to satisfy Intellisense may not be a good idea and may cause potential problems if it's not a simple demo case but a more realistic scenario. Hope this can be fixed soon. — Leon Cruz, Nov 10 '20 at 10:15

Visual Studio Intellisense not working when inheriting from template class

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