[Numpy-discussion] long double woes on win32

Charles R Harris charlesr.harris at gmail.com
Fri Aug 15 20:11:48 EDT 2008


On Fri, Aug 15, 2008 at 5:43 PM, David Cournapeau <cournape at gmail.com>wrote:

> Hi,
>
> The test failures on windows with 1.2b2 are due to buggy long double
> behavior of mingw. My understanding is that on windows, long double is
> 8 bytes (that's the sizeof value returned by VS 2003), but mingw says
> 12 bytes.
>

Doesn't mingw use the MSVC library? IIRC, in MSVC  long doubles and doubles
are the same type, so this seems to be a bug in mingw. I suppose numpy could
detect this situation and define the types to be identical, but if this is
impractical, then perhaps the best thing to do is issue an error message.


>
> One solution would be forcing numpy to configure itself to handle long
> double as double. But doing this breaks the configuration in many
> ways, and this would require relatively important changes which is
> quite fragile in numpy ATM (the whole math function things in
> umathmodule.c.src). I don't see this happening for 1.2.
>
> Another one is to use VS 2003 for the binaries: but then we are back
> to the problem of non buildable numpy with VS 2003.
>
> The last one is to ignore this for 1.2 (long double was already broken
> before in numpy win32 binaries).
>
> What do people think ?
>

There's isn't much you can do about long doubles while maintaining MSVC
compatibility.

Chuck
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