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From: "supercilious.dude at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/55159] New: pythy constexpr auto lambda pointer has no initializer
Date: Thu, 01 Nov 2012 00:33:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55159

             Bug #: 55159
           Summary: pythy constexpr auto lambda pointer has no initializer
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: supercilious.dude@gmail.com


Pythy (http://pfultz2.github.com/Pythy/) does something akin to:

template <typename T> 
typename std::remove_reference<T>::type *addr(T &&t) 
{ 
    return &t; 
}

template <class T0, class T1>
struct min_t
{
    constexpr static auto *f =
        false ? addr([](T0 x, T1 y){ return x < y ? x : y; }) : nullptr; 
};

Which gcc (4.7.2 and 4.8.0 git master) cannot evaluate.
clang and visual studio 2012 work fine.

I know this is not strictly needed by gcc 4.8 since it has deduced auto without
the late specifier (which the other compilers lack), but its highly convenient
to have pythy work on all c++11 compilers.