When building a binary or library, specifying the rpath, i.e.
-Wl,rpath,
tells the linker where to find the
In the case of rpath, it makes no sense to use a relative path, since a relative path will be relative to the current working directory, NOT relative to the directory where the binary/library was found. So it simply won't work for executables found in $PATH or libraries in pretty much any case.
Instead, you can use the $ORIGIN "special" path to have a path relative to the executable with-Wl,-rpath,'$ORIGIN' -- note that you need quotes around it to avoid having the shell interpret it as a variable, and if you try to do this in a Makefile, you need $$ to avoid having make interpret the $ as well.