Variable template in template class - unexpected error (possible bug?)

Question

Having:

struct Value
{
    template
    static constexpr T value{0};
};

---

(0) ideone

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Answer 1

This is definitely a gcc and clang bug in their treatment of variable templates as dependent names. I submitted gcc 67248 and clang 24473.

As a workaround for now, both compilers support the old way of doing variable templates, namely if you added:

struct Value
{
    template
    static constexpr T value = 0;

    template 
    struct variable_template_ish {
        static constexpr T value = Value::value;
    };
};

then the following compiles:

template
struct Something
{
    void foo() {
        static_assert(TValue::template variable_template_ish::value == 0, "");
    }
};

int main() { 
    Something{}.foo();
}