[Bug c/40442] Option -I and POSIX conformance (c99 utility)

[joseph at codesourcery dot com]

------- Comment #5 from joseph at codesourcery dot com  2009-06-15 13:06 -------
Subject: Re:  Option -I and POSIX conformance (c99 utility)

On Mon, 15 Jun 2009, vincent at vinc17 dot org wrote:

> ------- Comment #4 from vincent at vinc17 dot org  2009-06-15 11:59 -------
> (In reply to comment #3)
> > If you have modified the implementation (by putting headers/libraries in 
> > standard directories where those headers/libraries were not provided by 
> > the implementation in those versions in those directories, for example), 
> > you are very definitely outside the scope of POSIX.
> 
> I'm not sure I understand what you mean. But the existing practice is that
> additional headers/libraries (i.e. not those defined by the C standard)
> provided by the vendor are stored under /usr/{include,lib}. And I don't think
> this goes against POSIX. Concerning /usr/local, the FHS says:
> 
>   The /usr/local hierarchy is for use by the system administrator when
>   installing software locally.
> 
> So, it should be safe to add libraries there. And again, this is the existing
> practice.

It is not, however, safe to add libraries there that in any way conflict 
with the libraries provided by the system in /usr (such as different 
versions of the same libraries).

A POSIX-conforming system should have a POSIX conformance document that 
explains the circumstances under which the claims of POSIX conformance are 
made.  Those circumstances will include restrictions on any modification 
of system directories, such as limits on the contents of files in /etc for 
the system to be conforming and limits on what may go in /usr/local if 
some POSIX applications search that directory by default.  This document 
is nothing to do with GCC on its own; it has to be provided by the system 
integrator and describes properties of the whole system.  If the document 
for the POSIX system you are using is inadequate, you should raise that 
with the system integrator (and if necessary with whoever certified 
conformance).  And if POSIX does not render undefined options that have 
the effect of changing internal configuration details of applications, 
where those details have to be in a particular form for conformance (for 
example, conformance requiring header and library directories in a 
particular order), this is a bug in POSIX.  -I or -L options pointing to 
any of an implementation-defined set of system directories, or any 
directory with duplicates of headers or libraries in system directories, 
should be undefined behavior.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40442