Explicit instantiation of a class with concept'ed methods
From
Bonita Montero@21:1/5 to
All on Sun Sep 19 13:33:02 2021
Look at this code:
#include <concepts>
using namespace std;
struct A
{
void op();
};
struct B
{
void op( bool );
};
template<typename T>
concept concept_C = is_same<T, A>::value || is_same<T, B>::value;
template<typename T>
requires concept_C<T>
struct C
{
void opA()
requires is_same<T, A>::value;
void opB( bool f )
requires is_same<T, B>::value;
T *pt;
};
template<typename T>
requires concept_C<T>
void C<T>::opA()
requires is_same<T, A>::value
{
pt->op();
}
template<typename T>
requires concept_C<T>
void C<T>::opB( bool f )
requires is_same<T, B>::value
{
pt->op( f );
}
template
struct C<A>;
template
struct C<B>;
MSVC will instantiate opA for A as well as B and opB
also for A as well as B and gives the following errors:
(42,10): error : too many arguments to function call, expected 0, have 1 (46,8): message : in instantiation of member function 'C<A>::opB'
requested here
(7,7): message : 'op' declared here
(34,9): error : too few arguments to function call, expected 1, have 0
(49,8): message : in instantiation of member function 'C<B>::opA'
requested here
(12,7): message : 'op' declared here
clang gives similar errors, but g++12 is smarter and skips inappropriate compilation, i.e. filters the functions through their concepts, i.e. it compiles opA only for A and opB only for B - so which compiler is right
here ? And is there a workaround ?
--- SoupGate-Win32 v1.05
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