The RPM macros Gnatmake_optflags and GPRbuild_optflags have so far included a
hard-coded -R, telling Gnatmake and GPRbuild that they should not add a
runpath to the binaries they build. (It doesn't work in all cases, but that's
a bug in Gnatmake that should be fixed.) Normally we don't want runpaths in
Fedora packages. There are however cases where it would be advantageous to
allow a runpath. Library packages can have test suits or auxiliary programs
that run during the build and need to link to the library in the build
directory, and they may rely on the automatic runpath for this. We saw an
example of this in Templates Parser, where LD_LIBRARY_PATH had to be used in
the spec to compensate for the lack of a runpath.
I've found a way to allow a spec file to enable the runpath when needed while
keeping it disabled by default. I've changed the macros so that -R is not
included if there is a macro named GNAT_add_rpath. By default there is no such
macro, so -R is passed to the builder and nothing changes from the current
state, but a spec file that needs a runpath can define GNAT_add_rpath, allowing
the GNAT tools to add their computed runpath to the binaries.
The -R flag is omitted only where Gnatmake_optflags or GPRbuild_optflags is
expanded below the point where GNAT_add_rpath is defined. Undefining
GNAT_add_rpath restores the default so that -R is again used in macro
expansions below that point. It can even be defined and undefined several times
within a spec file if a runpath needs to be added in some builder invocations
and not in others.
Here's an example of how GNAT_add_rpath can be used in templates_parser.spec:
%build
make %{?_smp_mflags} VERSION=%{version} GNATMAKE_OPTFLAGS="%{Gnatmake_optflags}"
# doc build wants to link to library
%global GNAT_add_rpath yes
make doc GNATMAKE_OPTFLAGS="%{Gnatmake_optflags}"
First the library itself is built without a runpath (would be, if Gnatmake
didn't have that bug). Then GNAT_add_rpath is defined before the documentation
is built, so when a number of programs are built and run as a part of the
documentation build, they have a runpath and can therefore link to the
library. This is cleaner than using LD_LIBRARY_PATH as the spec file becomes
less dependent on the internal structure of the source tree.
This feture is coming to Fedora 17, 18 and Rawhide in fedora-gnat-project-
common-3.5-1. Adding it to Fedora 16 would be a little more work, but I can
get it in there too if there is a need for it.
Björn
