Cygwin Perl and -Duselongdouble

Thu Jul 26 13:27:00 GMT 2007

----- Original Message ----- 
From: "Brian Dessent" <>
To: <>
Sent: Thursday, July 26, 2007 10:29 PM
Subject: Re: Cygwin Perl and -Duselongdouble

> Sisyphus wrote:
>> I haven't checked for 'modfl' and 'frexpl', but 'sqrtl' at least seems to 
>> be
>> available in the C compiler. Why does configure report that it's not
> Why do you say this?

Oh ... it's probably just ignorance on my part.
If I can successfully run 'gcc script.c' (where 'script.c' contains a call 
to 'sqrtl') then I'm inclined to say that sqrtl is "available in the C 
compiler" (or something like that).

I gather from your response (and Corinna's) that there are also a couple of 
things called 'newlib' and 'libc' that enter into the equation. I don't know 
how they fit in. Feel free to enlighten me (but only if you're so inclined, 
as I realise that such an explanation is probably not on topic for this 

I find it all quite confusing. My MinGW version of math.h specifically 
prototypes the "long double" version of a number of functions (ceill, 
floorl, sqrtl, modfl, ...), yet I can't find any mention of those functions 
in any of the gcc headers on Linux or Cygwin.

If I call sqrtl on linux I have to link to -lm, on Cygwin I don't.

On linux I can build perl with -Duselongdouble, on Cygwin I can't.

Anyway .... I gather that -Duselongdouble is out of the question while 
newlib remains in its current state. (That's pretty much the confirmation I 
was seeking.)

Thanks guys.


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