Within the section 9.2.4 The typedef specifier of the C++ 20 Standard in the example2 of the paragraph 2 there is such an alias declaration
 
using cell = pair<void*, cell*>; // error
 
There is said nothing why this declaration is incorrect. So this example only confuses readers of the section. Actually such a declaration can be valid. Consider the following program
 
#include <utility>
 
using cell = int;
 
int main()
{
    using cell = std::pair<void *, cell *>;
    
    return 0;
}
 
According to the C++ 20 Standard (6.4.2 Point of declaration), p.3 ) «The point of declaration of an alias or alias template immediately follows the defining-type-id to which the alias refers»
 
So in the above program cell within the defining-type-id refers to the typedef id cell declared in the global namespace.
 
So just to write «error» for this line in the C++ Standard is not enough. Either this example should be excluded or appended with an explanation why there is an error.
 
With best regards
(Vlad from Moscow)
 
 
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