Xcode 15 and GCC: linker complains that "duplicate LC_RPATH are deprecated"

[szhorvat (Szabolcs Horvát)]

When linking to shared libraries that were compiled with GCC, e.g. ports that need gfortran, the linker included in Xcode 15 issues this warning:

$ cc xx.c -L/opt/local/lib -lopenblas
ld: warning: duplicate LC_RPATH are deprecated ('/opt/local/lib/libgcc')

Here openblas is just an example of such a library, and xx.c can be a trivial program with an empty main function.

This is well beyond my expertise, but I think it's related to the rpath entries here:

$ otool -L /opt/local/lib/libopenblas.1.dylib
/opt/local/lib/libopenblas.1.dylib:
	/opt/local/lib/libopenblas-r1.dylib (compatibility version 0.0.0, current version 0.0.0)
	@rpath/libgfortran.5.dylib (compatibility version 6.0.0, current version 6.0.0)
	@rpath/libquadmath.0.dylib (compatibility version 1.0.0, current version 1.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1319.100.3)

There's a separate issue that trying to use GCC triggers an assertion failure in the linker, but I'm sure you're aware of that (see e.g. this SO search: ​https://stackoverflow.com/search?q=file+Relocations.cpp%2C+line+1336 )

[cjones051073 (Chris Jones)]

You are using the wrong otool option above. You need to use -l (lower case) and check the RPATH entries. What you will find is there are duplicates in that list, which is precisely what the above warning is telling you.

I don’t at this time believe this is something we are doing wrong in the macports gcc packaging, but I could be wrong. I more suspect this is just something upstream GCC will have to address themselves. For now ignore the warnings.

Yes, I am aware of the linker issue as well. This is also I believe either an Xcode, or GCC issue, so the fix will have to come from one or other of those parties as well.

[cjones051073 (Chris Jones)]

Update. The warning could be related to

​https://github.com/macports/macports-ports/blob/f423d77fb2814f148c5b6dadcedeadd7c9ac6679/_resources/port1.0/group/compilers-1.0.tcl#L841

Someone might need to review if that workaround is still needed and if it is indeed the cause of the issue.

[ddrum2000]

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