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Re: [C++ Patch] for c++/54537

From: Jason Merrill <jason at redhat dot com>
To: Fabien Chêne <fabien dot chene at gmail dot com>
Cc: Paolo Carlini <paolo dot carlini at oracle dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, libstdc++ at gcc dot gnu dot org
Date: Thu, 23 May 2013 00:36:41 -0400
Subject: Re: [C++ Patch] for c++/54537
References: <CAFH4-dhvTpRyzTNpieNnZ=VMDcRE7+wikB4pk3dadFSNs0BK8g at mail dot gmail dot com> <504D3146 dot 8070108 at redhat dot com> <CAFH4-dgOgUEgzumgy891xVUieU2vugGxw2=_-_ezdpfXzZV7RQ at mail dot gmail dot com> <CAFH4-dhcjdoYkxb7gLygQBwv9S02Lue9zoRFE0SBLwemLAc-uQ at mail dot gmail dot com> <ff93ce3c-2523-42b9-b801-96e667058527 at email dot android dot com> <CAFH4-dhNT8LsqTBuQkRJO9HA+CAbmqQ44OA6PAUusWcn2cWoVg at mail dot gmail dot com> <a0f17889-3346-4ae9-80c6-28e7e5361f73 at email dot android dot com> <5058FFC4 dot 4020905 at oracle dot com> <50590293 dot 7050904 at oracle dot com> <50590676 dot 4090705 at oracle dot com> <CAFH4-dgRJz5+i4UxRSmGNXkKe6fKLq8Yezw5tosmHjA8tiw7DQ at mail dot gmail dot com> <505A1002 dot 3040200 at oracle dot com> <CAFH4-dj3ZQqhrJ93rxMg_z4eZryKRH+j_jsZ7_cX5Wx9E1BGGA at mail dot gmail dot com> <50A4099F dot 1080409 at oracle dot com> <50A40A7B dot 30809 at redhat dot com> <CAFH4-dgycCh=JbQ3MSnHE86FQ=bUjEQZdT8-h5371cwzQkQh0g at mail dot gmail dot com> <50A50028 dot 7060303 at redhat dot com> <CAFH4-dimUUJvcSQ5LGhghzGcUPibxvCEKmXWd-+aE0VRcpDocA at mail dot gmail dot com>

On 05/22/2013 04:53 PM, Fabien Chêne wrote:

Ah, I see, it works. Then we end up with three solutions:
1) remove the pow(double,double) overload
2) add a specialization template <> pow(double,double)
3) add an extern "C" declaration to refer to the C library function

I don't have a strong preference, I would say that all solutions are
more or less equivalent. In the end, builtins are just reached in
different ways I guess, depending on the optimisations enabled.
Given that Paolo already OKed the solution 1), I would go for it.

I guess #1 and #2 involve forwarding through a template, whereas #3avoids that and might give cleaner code without optimization. Butlibrary design issues might be more important, so library folks shouldmake the call here.


Jason

References:
- Re: [C++ Patch] for c++/54537
  - From: Fabien Chêne

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