Re: order dependence of -l option

[Brad Finney <Brad dot Finney at humboldt dot edu>]

On 2/8/2012 10:31 PM, Steve Kargl wrote:
> On Wed, Feb 08, 2012 at 10:19:23PM -0800, Brad Finney wrote:
> > Why must the -l<library>  argument be placed after the fortran source
> > file name when compiling with gfortran.
> >
> > The following does not find object codes in libutil.a
> >
> > gfortran -Llib -lutil a.f90
> >
> > but the following works as expected
> >
> > gfortran -Llib a.f90 -lutil
> >
> > I understand that the order of -l arguments matter is there are multiple
> > libraries, but I do not understand why gfortran doesn't just pass the
> > -l<library>  arguments on to the linker after creating a.o.
>
> a) history
> b) simplicity
> c) causality
> d) all of the above
>
> How is the loader to know that _foo in -lutil is
> needed by the code in a.f90?  Or, are you suggesting
> that the loader should retain all symbols in -lutil?
No, I am expecting exactly what happens.  The loader scans for missing 
symbols in library libutil.a which is found either in the working 
directory or the directory identified as lib.  The question is why is 
the order of the -l option critical when most other options can be in 
any order.  Obviously I am missing some key feature/characteristic of 
the process.  I don't have any problem following the "rule", but 
understanding the why is helpful.  Sorry to trouble you with the question.