Re: Library file locations (was: Debian Policy for Ada, Second Edition)

[Tapio Kelloniemi <spam18@thack.org>]

Ludovic Brenta <ludovic@ludovic-brenta.org> wrote:
>Tapio Kelloniemi <spam18@thack.org> writes:
>[...]
>> However GCC searches for header files in /usr/include and
>> /usr/local/include even when it is installed under /opt. If some
>> other behaviour is desired, GCC specs must be modified. So either
>> GNAT should also use the same specs machanism as the rest of GCC (we
>> agree that GNAT should behave the same way as other compilers in
>> GCC?) or it should:
>>
>> - Search from /usr/local if and only if it will be installed to /usr.
>> and/or
>> - Provide an easy way for system administrators to change the project search
>>   path. Perhaps a file like ada_project_path could be added to lib/gcc/*/*
>>   where ada_object_path and ada_source_path files may also reside.
>
>In particular, /usr/local is, by definition, for use by the system
>administrator, and therefore falls outside the scope of any policy
>defined by the operating system.

Why GCC then looks for headers in /usr/local/include? Because many packages
are installed in /usr/local by sysadmins and because /usr/local/include
is in GCC's default search path, other packages can link against 
packages installed by admin without using absolute paths. Has anyone ever
seen C code like:
#include "/usr/local/include/readline/readline.h"

What comes to setting ADA_PROJECT_PATH, I think it is just setting
one more redundant environment variable. Editing a text file is much more
elegant solution.

> If you want GNAT to look in some
>particular subdirectory of /usr/local, then use ADA_PROJECT_PATH or
>"with" the fully qualified file name of your project files.

Let us think that I'm to publish my application A in source format on my
web site. The package is built with a command like:
gnatmake -PA

If my project file contains something like:
with "/usr/share/ada/adainclude/florist.gpr";
with "/...";
with "/...";

Suddenly I'll get a lot of complaints that compiling my application is very
frustrating because users must hassle with the absolute path definitions
in my project file.

>So, what exactly is the problem?

Easy usage of libraries, no matter whether they are installed by a sysadmin
or a distro.

--
Tapio