Re: Fwd: Inconsistent warning/error message by GCC while linking 32/64 bit binary/library

[Nick Clifton <nickc at redhat dot com>]

Hi Vijay,

> Vijay bsd84:~/lib]# gcc -g -m32 b.o -L. -la
> /usr/bin/ld: skipping incompatible ./liba.a when searching for -la
> /usr/bin/ld: cannot find -la

> Vijay bsd84:~/lib]# gcc -g -m32 b.o liba.a
> /usr/bin/ld: warning: i386:x86-64 architecture of input file
> `liba.a(a.o)' is incompatible with i386 output

The warnings are different because you are asking the linker to perform 
slightly different things.  In the first example the "-la" option means 
"search all of the library paths for a library called 'a' and include it 
at this point in the link".  Hence the linker issues a warning message 
when it finds a library called 'a', but it is of an incompatible 
architecture.  The assumption being that there is likely to be a problem 
with one or more of the -L options provided since they have lead the 
linker to look in a directory containing incompatible binaries.

In the second example you have provided the location of the 'a' library 
directly - no searching is needed by the linker.  In this case a 
different warning is issued because the problem is different - you are 
asking the linker to link in an incompatible binary, rather than asking 
it to search in the wrong place.

I hope that this helps.

Cheers
  Nick