[Bug c++/55834] New: Undefined reference to static template member using lambda to function pointer conversion.

[splinterofchaos at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55834



             Bug #: 55834

           Summary: Undefined reference to static template member using

                    lambda to function pointer conversion.

    Classification: Unclassified

           Product: gcc

           Version: 4.7.2

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: c++

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: splinterofch...@gmail.com





The following code is accepted by clang 3.2, but causes 3.0 to crash. Gcc 4.7

and 4.8 emit undefined references.



#include <iostream>



template< size_t k > struct Mod {

    int i;



    static Mod div0(int x,int y){ return x/y; }



    typedef Mod(*func1)(int,int);

    static func1 div1;



    constexpr Mod( int i ) : i(i) { }



    constexpr operator int () { return i; }

};



typedef int(*ii2i)(int,int);



template< size_t k >

typename Mod<k>::func1 Mod<k>::div1 = []( int x, int y ) { return Mod<k>(x /

y); };



// Ok

//Mod<3> div3( int x, int y ) { return x/y; }

//template< size_t k >

//typename Mod<k>::func1 Mod<k>::div1 = div3;



template struct Mod<3>;

int main() {

    std::cout << Mod<3>::div0(10,2) << std::endl;

    std::cout << Mod<3>::div1(10,2) << std::endl; // undefined

}



version:

$ g++ -v

Using built-in specs.

COLLECT_GCC=g++

COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper

Target: x86_64-linux-gnu

Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro

4.7.2-5ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs

--enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr

--program-suffix=-4.7 --enable-shared --enable-linker-build-id

--with-system-zlib --libexecdir=/usr/lib --without-included-gettext

--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7

--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu

--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object

--enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686

--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu

--host=x86_64-linux-gnu --target=x86_64-linux-gnu

Thread model: posix

gcc version 4.7.2 (Ubuntu/Linaro 4.7.2-5ubuntu1)