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From: "splinterofchaos at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/55834] New: Undefined reference to static template member using lambda to function pointer conversion.
Date: Mon, 31 Dec 2012 16:04:00 -0000
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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: unassigned@gcc.gnu.org
        ReportedBy: splinterofchaos@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)