[Issue 20296] Segfault when using variadic D functions with extern(C++) linkage

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20296

--- Comment #4 from moonlightsentinel at disroot.org ---
(In reply to moonlightsentinel from comment #3)
> This is actually a regression:

(Found using a modified test case which defines 

==================================
void main()
{
    foo!(char*)(null);
}
==================================

instead of an alias.

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