This PR fixes compilation errors with VS 2017 (/std:c++latest /permissive-).
VS 2017 seems to have a very strict interpretation of [temp.deduct.guide] (3):
... Two deduction guide declarations in the same translation unit for the same class template shall
not have equivalent parameter-declaration-clauses.
Both gcc and clang seem to ignore [temp.deduct.guide] (3), or only considering it for viable CTAD candidates.
NB: There seems to be no explicit explanation, when two parameter-declaration-clauses are equivalent, especially if templates are involved.
This PR fixes compilation errors with VS 2017 (/std:c++latest /permissive-). VS 2017 seems to have a very strict interpretation of [temp.deduct.guide] (3):
Both gcc and clang seem to ignore [temp.deduct.guide] (3), or only considering it for viable CTAD candidates.
NB: There seems to be no explicit explanation, when two parameter-declaration-clauses are equivalent, especially if templates are involved.