How to specify explicit requires on library

[Sandro Mani]

Hello,

I was looking at the gdal spec [1] and noticed the following lines in %prep

# libproj is dlopened; upstream sources point to .so, which is usually 
not present
# http://trac.osgeo.org/gdal/ticket/3602
sed -i 's|libproj.so|libproj.so.0|g' ogr/ogrct.cpp

The problem is that a libproj soname bump will be silently missed unless 
a maintainer remembers the existence of this particular line - and 
indeed, the libproj soname was bumped in proj-4.9.1 to libproj.so.9.

I was about to file a bug suggesting

# Major digit of the proj so version
%global proj_somaj 9
[...]
# proj DL-opened in ogrct.cpp, see also fix in %%prep
Requires: libproj.so.%{proj_somaj}
[...]
sed -i 's|libproj.so|libproj.so.%{proj_somaj}|g' ogr/ogrct.cpp

but I haven't found how to correctly specify the explicit arch-correct 
requires on the library. I suppose I want something which will 
ultimately results in something like

Konsole output
libproj.so.9()(64bit)

but how can the "()(64bit)" part be specified?


Thanks,
Sandro


[1] http://pkgs.fedoraproject.org/cgit/gdal.git/tree/gdal.spec