https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67970
Bug ID: 67970
Summary: [concepts] variable template bug
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ryan.burn at gmail dot com
Target Milestone: ---
The below code should compile, but I get this error:
bug.cpp: In function ‘int main()’:
bug.cpp:29:13: error: the value of ‘match_numeric_array’ is not usable in a
constant expression
func(0, v5);
^
bug.cpp:8:5: note: ‘match_numeric_array’ used in its own initializer
match_numeric_array<NumericArray<Scalar>> =
^
bug.cpp:29:13: error: ‘<expression error>’ is not a constant expression
func(0, v5);
///////////////////////////////////////////////////////////////////
template <class>
class NumericArray {};
template <class>
constexpr bool match_numeric_array = false;
template <class Scalar>
constexpr bool
match_numeric_array<NumericArray<Scalar>> =
true;
template <class T>
concept bool cpt_NumericArrayContainer() {
return match_numeric_array<T>;
}
template <class X>
concept bool cpt_NumericArray() {
return requires{requires cpt_NumericArrayContainer<X>()};
}
template <class X>
requires !cpt_NumericArray<X>() auto func(int, X) {}
template <class X>
requires cpt_NumericArray<X>() auto func(int, X) {}
int main() {
NumericArray<double> v5;
func(0, v5);
}
///////////////////////////////////////////////////////////////////
