Re: --help should not require --srcdir

[Eric Blake]

On 07/28/2011 12:13 PM, Sam Steingold wrote:
> > * Eric Blake<address@hidden>  [2011-07-28 11:35:30 -0600]:
> >
> > > However, there is no reason for any program to report an error when
> > > given the --help switch, no matter where the program is located.
> >
> > Yes there is, if the program can do nothing useful in its current
> > location.
>
> try "ls --help" in an unreadable directory.
> it will print help, not report an error saying that the current
> directory is not readable.

ls is location-independent.  It is designed to run no matter where 
either ls is located or where the current working directory is.

configure is location-dependent.  It is only designed to do something 
useful when located in alongside the sources that it was generated from. 
 However, while it matters in which directory configure lives, it does 
_not_ matter where the current working directory is - you can run 
/path/to/configure, ../configure, or any other construct where a 
correctly-located configure living in an appropriate srcdir, distinct 
from your choice of current working directory.

I don't buy your argument as justification for always making ./configure 
--help succeed, when ./configure was moved out of place.  And I already 
told you that I welcome patches that make configure give nicer error 
messages stating that the script is useless when not located correctly.

Additionally, there's a difference between code that can be run from 
anywhere (configure and ls both fit this) and relocatable code (ls is 
typically relocatable, configure is not).  GNU Coding Standards do not 
require relocatable code, and when you look at packages like gettext 
that provide relocatable binaries, you can see why that is such a 
difficult bonus feature to add.  And even then, while gettext is 
relocatable, it is only relocatable if you move ALL of the helper files 
that the primary binary uses to reside in a parallel directory structure 
similar to where the binary was originally installed.  If you relocate 
the main binary but not the helper scripts and shared libraries, then 
the binary in the new location will not function correctly.  You can 
think of configure scripts in the same manner - they can be invoked from 
anywhere, but if relocated, you must also relocate everything else that 
the script needs for full functionality.

--
Eric Blake   address@hidden    +1-801-349-2682
Libvirt virtualization library http://libvirt.org