-rpath $ORIGIN is ignored at link time with GNU ld

[nirbheek]

https://sourceware.org/bugzilla/show_bug.cgi?id=16936

The best way to fix this while also preserving both $ORIGIN in the DT_RPATH of the output and the changes in #1545 is to also pass -Wl,-rpath-link with the full path to the subdirectories (without $ORIGIN).

I checked and this does work as we want it to. But I am not sure why this wasn't caught on the CI. A lot of tests are failing on my machine (Fedora 25, binutils 2.26.1).

Will submit a PR with a test for this.

[nirbheek]

For example:

meson.git/test cases/common/46 library chain $ ninja -C build
ninja: Entering directory `build'
[11/11] Linking target prog.
FAILED: prog 
ccache cc  -o prog 'prog@exe/main.c.o' -Wl,--no-undefined -Wl,--as-needed subdir/liblib1.so '-Wl,-rpath,$ORIGIN/subdir:$ORIGIN/subdir/subdir2:$ORIGIN/subdir/subdir3'  
/usr/bin/ld: warning: liblib2.so, needed by subdir/liblib1.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: liblib3.so, needed by subdir/liblib1.so, not found (try using -rpath or -rpath-link)
subdir/liblib1.so: undefined reference to `lib3fun'
subdir/liblib1.so: undefined reference to `lib2fun'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.

This works:

ccache cc -o prog 'prog@exe/main.c.o' -Wl,--no-undefined -Wl,--as-needed subdir/liblib1.so '-Wl,-rpath,$ORIGIN/subdir:$ORIGIN/subdir/subdir2:$ORIGIN/subdir/subdir3' "-Wl,-rpath-link,$PWD/subdir:$PWD/subdir/subdir2:$PWD/subdir/subdir3"

And readelf:

$ readelf -a prog | grep -i rpath
0x000000000000000f (RPATH) Library rpath: [$ORIGIN/subdir:$ORIGIN/subdir/subdir2:$ORIGIN/subdir/subdir3]

I also verified manually by relocating prog to another directory.