boost::rational issue with ios_base constructor

[john-d-murphy]

Code fails to compile if boost::rational is used as the parameter to a function that also shares a signature with a void* - for example:

#include <boost/rational.hpp>

void foo(void(*)()) {}
void foo(boost::rational<int>) {}

void fun() {}

int main() {
  foo(fun);
}

https://wandbox.org/permlink/a06FvkYIP5asIys0

This returns an error in from /opt/wandbox/gcc-head/include/c++/11.0.0/bits/ios_base.h:41,

Apologies since I'm not familiar with the code enough to give a better example/understanding of what's happening. Please let me know what other information I can provide or how I can help get this sorted.

thanks,
John

[mclow]

It looks to me like it trying to instantiate std::numeric_limits<void ()> which doesn't go well.

/opt/wandbox/gcc-head/include/c++/11.0.0/limits: In instantiation of 'struct std::numeric_limits<void()>':
/opt/wandbox/boost-1.73.0/gcc-head/include/boost/rational.hpp:123:7:   required from 'const bool boost::rational_detail::is_compatible_integer<void(), int, void>::value'
/opt/wandbox/boost-1.73.0/gcc-head/include/boost/rational.hpp:184:21:   required by substitution of 'template<class T> constexpr boost::rational<int>::rational(const T&, const typename boost::enable_if_c<boost::rational_detail::is_compatible_integer<T, int, void>::value, void>::type*) [with T = void()]'
prog.cc:9:10:   required from here

[mclow]

Also, I get the same error from clang/libc++