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Ambiguous deduction guides in C++23 mode #46
Description
Just trying this with gcc 14, any use of the fixed_string "alias" type fails to compile with -std=c++23:
#include <fixed_string.hpp>
template<fixstr::fixed_string>
struct stringy_type { };
using foo = stringy_type<"hello">;$ g++-14 -I include -std=c++23 -c test.cpp
test.cpp:6:33: error: class template argument deduction failed:
6 | using foo = stringy_type<"hello">;
| ^
test.cpp:6:33: error: call of overloaded ‘fixed_string(const char [6])’ is ambiguous
In file included from test.cpp:1:
include/fixed_string.hpp:518:1: note: candidate: ‘fixstr::basic_fixed_string(const char (&)[N])-> fixed_string<(N - 1)> [with long unsigned int N = 6]’
518 | basic_fixed_string(const TChar (&)[N]) -> basic_fixed_string<TChar, N - 1>;
| ^~~~~~~~~~~~~~~~~~
include/fixed_string.hpp:529:1: note: candidate: ‘fixstr::fixed_string(const char (&)[N])-> fixed_string<(N - 1)> [with long unsigned int N = 6]’
529 | fixed_string(const char (&)[N]) -> fixed_string<N - 1>;
| ^~~~~~~~~~~~
Activity
unterumarmung commentedon Aug 16, 2024
Oh I'm sorry for the long response. I've not seen the notification from GitHub.
To be honest, I've never tested this library with newer compilers. I wrote it when C++20 wasn't very well supported and that's why there are some workarounds...
I'm not sure when I'll be able to test the issue and come up with a solution, but if you have one, I'll be glad to review it and merge.
unterumarmung commentedon Aug 16, 2024
fixed_string/include/fixed_string.hpp
Line 520 in 8a46a22
I guess these lines should be rewritten to type aliases and the support for the old GCC versions to be dropped