I introduced a patch to handle unqualified templated base class
initialization in MSVC compatibility mode:
https://reviews.llvm.org/rGc894e85fc64dd8d83b460de81080fff93c5ca334
We identified a problem with this patch in the case where the base class
is partially specialized, which can lead to triggering an assertion in
the case of a mix between types and values.
The minimal test case is:
template <typename Type, int TSize> class Vec {};
template <int TDim> class Index : public Vec<int, TDim> {
Index() : Vec() {}
};
template class Index<0>;
The detailed problem is that I was using the
`InjectedClassNameSpecialization`, to which the class template arguments
were then applied in order. But in the process, we were losing all the
partial specializations of the base class and creating an index mismatch
between the expected and passed arguments.
Patch By: frederic-tingaud-sonarsource
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D130709
Before C++20, MSVC was supporting not mentioning the template argument of the base class when initializing a class inheriting a templated base class.
So the following code compiled correctly:
```
template <class T>
class Base {
};
template <class T>
class Derived : public Base<T> {
public:
Derived() : Base() {}
};
void test() {
Derived<int> d;
}
```
See https://godbolt.org/z/Pxxe7nccx for a conformance view.
This patch adds support for such construct when in MSVC compatibility mode.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D124666
Fred Tingaud