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Date: Fri, 30 Jan 2009 14:03:25 +0100 (CET)
From: Marco Atzeri <marco_atzeri@yahoo.it>
Subject: Re: C++ ambiguous template specialization (cygwin only)
To: Dave Korn <dave.korn.cygwin@googlemail.com>, cygwin@cygwin.com
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--- Dave Korn ha scritto:

> Marco Atzeri wrote:
> > Dear all,
> > unfortunately I am not too much familiar with C++,
> > so I have no clue where to look for difference
> > between Cygwin and all the other platforms where
> this
> > problem does not happen.
> 
 > 
>   Hmm.  The generic template with the <T> is less
> specific and shouldn't
> matter if there's a more-specific one, which there
> is.  So, why doesn't the
> (uint64_t, double) version match?  Well, looking at
> the other possible
> matches, it seems to think that int64_t is as near a
> match.  I wonder if when
> it doesn't have an exact match, it sees
> sign-extension and size-promotion as
> equally different and therefore equally similar and
> therefore ambiguous.  You
> could find a C++ expert to explain the resolution
> rules for you, but I think
> that's the sort of basis on which it works.
> 
>   I wonder what would happen if, on Cygwin, uint64_t
> was a typedef for
> unsigned long long int.  

Just tested and the ambiguity go away.
Now I will look for the right way to solve the issue,
instead of changing stdint.h.


> Does it help if you comment
> out the <double, long
> long unsigned int> template on line 198, leaving
> just the <double, uint64_t>
> on line 127 to be a precise match?
> 
>     cheers,
>       DaveK
> 

Thanks for the hint
Marco



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