https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100381
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The code is definitely invalid.
Your code instantiates std::function<void(CallParameter)> where CallParameter
is IndexGroupsAndNames which is an incomplete type. Constructing a
std::function checks that the callable argument is invocable with the argument
types in the std::function's call signature, which is void(CallParameter).
That is done using std::is_invocable_r. The spec for std::is_invocable_r<R, Fn,
ArgTypes...> has this requirement:
"Fn, R, and all types in the template parameter pack ArgTypes shall be complete
types, cv void, or arrays of unknown bound."
So you're trying to construct std::function<void(IncompleteType)> which needs
to check if you can call a function with an argument of type IncompleteType,
which cannot be determined because the type might be non-copyable.
Using std::function<void(const CallParameter&)> would work, so would ensuring
the type is complete before trying to use it in a std::function call signature.
