https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66834
Bug ID: 66834
Summary: [concepts] concept parameter kind mismatch causes hard
error
Product: gcc
Version: c++-concepts
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: eric.niebler at gmail dot com
Target Milestone: ---
Before rev 225651 (the fix for #66758), the following worked. It no longer
does. Not sure if it's legit.
template <class From, class To>
concept bool ExplicitlyConvertible =
requires (From&& f) {
static_cast<To>((From&&)f);
};
template <class T, class... Args>
concept bool Constructible =
ExplicitlyConvertible<Args..., T> ||
requires (Args&&... args) {
T{((Args&&)(args))...};
};
template <class T, class...Args>
constexpr bool constructible() { return false; }
Constructible{T, ...Args}
constexpr bool constructible() { return false; }
int main() {}
Yields:
/cygdrive/c/Users/eric/Code/cmcstl2/test/iterator.cpp: In function ‘constexpr
bool Constructible()’:
/cygdrive/c/Users/eric/Code/cmcstl2/test/iterator.cpp:9:5: error: pack
expansion argument for non-pack parameter ‘From’ of concept ‘template
<class From, class To> constexpr const bool ExplicitlyConvertible<From, To>’
ExplicitlyConvertible<Args..., T> ||
^
/cygdrive/c/Users/eric/Code/cmcstl2/test/iterator.cpp:1:11: note: declared here
template< class From, class To >
^
