llvm-3.8: llvm ld: unknown option: -export_dynamic

[gbrtrac]

There is an unknown linker flag being used in the building of llvm

:info:build /opt/local/bin/clang++-mp-3.7   -pipe -Os -std=c++11 -stdlib=libc++ -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -std=c++11 -DNDEBUG -arch x86_64 -mmacosx-version-min=10.9 -Wl,-search_paths_first -Wl,-headerpad_max_install_names -L/opt/local/lib -Wl,-headerpad_max_install_names  -rdynamic CMakeFiles/bugpoint.dir/BugDriver.cpp.o CMakeFiles/bugpoint.dir/CrashDebugger.cpp.o CMakeFiles/bugpoint.dir/ExecutionDriver.cpp.o CMakeFiles/bugpoint.dir/ExtractFunction.cpp.o CMakeFiles/bugpoint.dir/FindBugs.cpp.o CMakeFiles/bugpoint.dir/Miscompilation.cpp.o CMakeFiles/bugpoint.dir/OptimizerDriver.cpp.o CMakeFiles/bugpoint.dir/ToolRunner.cpp.o CMakeFiles/bugpoint.dir/bugpoint.cpp.o  -o ../../bin/bugpoint -Wl,-rpath,/opt/local/libexec/llvm-3.8/lib  ../../lib/libLLVM.dylib 
:info:build ld: unknown option: -export_dynamic

[jeremyhu (Jeremy Huddleston Sequoia)]

What is the output of:

/opt/local/libexec/llvm-3.7/bin/ld -v

[jeremyhu (Jeremy Huddleston Sequoia)]

Note that's just a warning from the linker. Are you seeing fallout from it?

[gbrtrac]

The "warning" actually stops the build -- treated as an error

/opt/local/libexec/llvm-3.7/bin/ld -v
@(#)PROGRAM:ld  PROJECT:ld64-136
configured to support archs: i386 x86_64 armv7 armv7s
LTO support using: LLVM version 3.7.1

[jeremyhu (Jeremy Huddleston Sequoia)]

What port were you trying to build when you encountered this error?

Please attach the full build log.

[gbrtrac]

The same thing happens if I clean and run the build

[jeremyhu (Jeremy Huddleston Sequoia)]

Why did you decide to use the +ld64_variant? ld64-136 is really only useful for Leopard. If you use ld64-latest instead, I expect you can get past this.

clang should be only setting that on newer versions of ld that support it (137+):

commit bd77c59acc58e797756b0fcc6739319587e95d85
Author: Bob Wilson <bob.wilson@apple.com>
Date:   Fri Aug 2 22:25:34 2013 +0000

    Only use the Darwin linker's -export_dynamic option with supported versions.
    
    Related to <rdar://problem/14578094>.
    
    git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187680 91177308-0d34-0410-b5e6-96231b3b80d8

[jeremyhu (Jeremy Huddleston Sequoia)]

Reduced:

$ clang-mp-devel -c true.c && clang-mp-devel -rdynamic true.o -v
...
 "/opt/local/libexec/llvm-devel/bin/ld" -demangle -export_dynamic -lto_library /opt/local/libexec/llvm-devel/lib/libLTO.dylib -dynamic -arch x86_64 -macosx_version_min 10.9.0 -o a.out true.o -lSystem /opt/local/libexec/llvm-devel/bin/../lib/clang/4.0.0/lib/darwin/libclang_rt.osx.a
ld: unknown option: -export_dynamic
clang: error: linker command failed with exit code 1 (use -v to see invocation)

$ /opt/local/libexec/llvm-devel/bin/ld -v
@(#)PROGRAM:ld  PROJECT:ld64-136
configured to support archs: i386 x86_64 armv7 armv7s
LTO support using: LLVM version 4.0.0svn

[jeremyhu (Jeremy Huddleston Sequoia)]

Filed upstream bug ​https://llvm.org/bugs/show_bug.cgi?id=31465

[jeremyhu (Jeremy Huddleston Sequoia)]

Do the following to fix this on your system:

sudo port -v -f deactivate ld64
sudo port -v install ld64 -ld64_136

This ticket tracks improving messaging to users and/or making this a bit more foolproof.

[gbrtrac]

That resolved it