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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/104567] SFINAE check failure with trying to access member
 field on the default template argument for a function
Date: Thu, 17 Feb 2022 10:38:51 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104567

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |12.0

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
A testcase that shows the bug is a lot more useful than one that needs
something uncommented to show the bug.

template <typename _TAny, char const* value =3D _TAny::param>
constexpr bool has_char_static_param(int)
    { return true; }

template <typename _TAny>
constexpr bool has_char_static_param(...)
    { return false; }

struct works1
{
    constexpr static char param[] =3D "param";
};

struct works2
{
    constexpr static int param =3D 0;
};

struct fails
{
    char const* param; // not static
};

static_assert(has_char_static_param<works1>(0), "");
static_assert(!has_char_static_param<works2>(0), "");
static_assert(!has_char_static_param<fails>(0), "");  // FAILS=