Re: Problem when a 32-bit library is linked instead of a 64-bit library

[Paul Eggert]

On 07/12/10 04:31, Dr. David Kirkby wrote:

> I know the following method works in some cases
> 
> export CLFAGS=-m64
> export LDFLAGS=-m64
> ./configure
> 
> other times (e.g. Python, Singular), one needs to define CC to be "gcc
> -m64".

Normally "configure" just uses the first compiler in your path,
preferring gcc to cc if it works.  If you want to use a compiler
in a non-default configuration (say, 64-bit), you need
to tell "configure" about it with something like this:

configure CC='gcc -m64 -L/usr/local/lib64 -R/usr/local/lib64'

using whatever options are needed on your platform to ensure that
64-bit libraries are linked from the correct location, both at
compile-time and at run-time.  This sort of approach is more
reliable than the CFLAGS / LDFLAGS stuff, since it handles
more-oddball problems better, for example, when a file is
preprocessed rather than compiled to a .o file and so
CFLAGS is not used.