https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115231
--- Comment #4 from huangqinjin at gmail dot com ---
g++ -fmodules-ts -std=c++20 module.cpp main.cpp
main.cpp: In function 'int main()':
main.cpp:11:15: error: class template argument deduction failed:
11 | A b(B{}, 1);
| ^
main.cpp:11:15: error: no matching function for call to 'A@Mod(B, int)'
In module Mod, imported at main.cpp:1:
module.cpp:11:9: note: candidate: 'template<class T> A@Mod(T)-> A@Mod<T>'
11 | A(T) {}
| ^
module.cpp:11:9: note: template argument deduction/substitution failed:
main.cpp:11:15: note: candidate expects 1 argument, 2 provided
11 | A b(B{}, 1);
| ^
In module Mod, imported at main.cpp:1:
module.cpp:9:9: note: candidate: 'template<class T, class U> A@Mod(U, int)->
A@Mod<T>'
9 | A(U, int) {}
| ^
module.cpp:9:9: note: template argument deduction/substitution failed:
main.cpp:11:15: note: couldn't deduce template parameter 'T'
11 | A b(B{}, 1);
| ^
In module Mod, imported at main.cpp:1:
module.cpp:6:12: note: candidate: 'template<class T> A@Mod(A@Mod<T>)->
A@Mod<T>'
6 | struct A
| ^
module.cpp:6:12: note: template argument deduction/substitution failed:
main.cpp:11:15: note: 'B' is not derived from 'A@Mod<T>'
11 | A b(B{}, 1);
| ^
