#51929: ld64-latest (and others?): default variant llvm38 breaks linking with pre-3.8-clang ---------------------+------------------------- Reporter: ionic@… | Owner: jeremyhu@… Type: defect | Status: new Priority: Normal | Milestone: Component: ports | Version: Keywords: | Port: ld64-latest ---------------------+------------------------- Recently, I changed my variants on `ld64-latest` and `cctools` from whatever I used before (probably `llvm33`) to the new default variant (`llvm38`) on OS X 10.9+ (with me being on 10.9.5.) While installing `clang-3.8` as a dependency of something else, I hit this error: {{{ -- Check for working C compiler: /opt/local/bin/clang-mp-3.7 -- broken CMake Error at /opt/local/share/cmake-3.6/Modules/CMakeTestCCompiler.cmake:61 (message): The C compiler "/opt/local/bin/clang-mp-3.7" is not able to compile a simple test program. It fails with the following output: Change Dir: /opt/local/var/macports/build/_opt_local_var_macports_sources_macports.rsync.ionic.de_release_ports_lang_llvm-3.8/clang-3.8/work/build/CMakeFiles/CMakeTmp Run Build Command:"/usr/bin/make" "cmTC_b11b8/fast" /Applications/Xcode.app/Contents/Developer/usr/bin/make -f CMakeFiles/cmTC_b11b8.dir/build.make CMakeFiles/cmTC_b11b8.dir/build Building C object CMakeFiles/cmTC_b11b8.dir/testCCompiler.c.o /opt/local/bin/clang-mp-3.7 -pipe -Os -arch x86_64 -mmacosx-version-min=10.9 -o CMakeFiles/cmTC_b11b8.dir/testCCompiler.c.o -c /opt/local/var/macports/build/_opt_local_var_macports_sources_macports.rsync.ionic.de_release_ports_lang_llvm-3.8/clang-3.8/work/build/CMakeFiles/CMakeTmp/testCCompiler.c Linking C executable cmTC_b11b8 /opt/local/bin/cmake -E cmake_link_script CMakeFiles/cmTC_b11b8.dir/link.txt --verbose=1 /opt/local/bin/clang-mp-3.7 -pipe -Os -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 -Wl,-rpath,@loader_path -Wl,-rpath,@loader_path/ CMakeFiles/cmTC_b11b8.dir/testCCompiler.c.o -o cmTC_b11b8 dyld: Library not loaded: @executable_path/../lib/libLTO.dylib Referenced from: /opt/local/libexec/llvm-3.7/bin/ld Reason: Incompatible library version: ld requires version 1.0.0 or later, but libLTO.dylib provides version 0.0.0 clang: error: unable to execute command: Trace/BPT trap: 5 clang: error: linker command failed due to signal (use -v to see invocation) }}} Further investigation revealed: {{{ root@nopileos~# ls -ldh /opt/local/libexec/llvm-3.7/bin/ld lrwxr-xr-x 1 root 26 Jul 27 23:42 /opt/local/libexec/llvm-3.7/bin/ld -> /opt/local/libexec/ld64/ld }}} So when using clang-3.7, the system-default linker as installed by `ld64`/the other `ld64-version` ports are used, good. {{{ root@nopileos~# otool -L /opt/local/libexec/llvm-3.7/lib/libLTO.dylib /opt/local/libexec/llvm-3.7/lib/libLTO.dylib: /opt/local/libexec/llvm-3.7/lib/libLTO.dylib (compatibility version 0.0.0, current version 0.0.0) /opt/local/libexec/llvm-3.7/lib/libLLVM-3.7.dylib (compatibility version 0.0.0, current version 0.0.0) [...] }}} `llvm-3.7`'s `libLTO` has compat version 0.0.0, current version 0.0.0. {{{ root@nopileos~# otool -L /opt/local/libexec/llvm-3.8/lib/libLTO.dylib /opt/local/libexec/llvm-3.8/lib/libLTO.dylib: @rpath/libLTO.dylib (compatibility version 1.0.0, current version 3.8.1) @rpath/libLLVM.dylib (compatibility version 1.0.0, current version 3.8.1) [...] }}} `llvm-3.8`'s `libLTO` changed the compat version to 1.0.0 and the current version to 3.8.1. {{{ root@nopileos~# otool -L /opt/local/libexec/ld64/ld /opt/local/libexec/ld64/ld: @executable_path/../lib/libLTO.dylib (compatibility version 1.0.0, current version 3.8.1) [...] }}} And the binary installed by `ld64-latest` (and symlinked via `ld64`) needs compat version 1.0.0. `clang-3.7` invokes `/opt/local/libexec/llvm-3.7/bin/ld`, so the expanded path to the library through `@executable_path` is `/opt/local/libexec/llvm-3.7/lib/libLTO.dylib`, which has (see above) a lower compat version of 0.0.0. Breakage. A fix might be to '''not''' use `@executable_path`, but rewrite the libLTO library dependency to always use the `libLTO` library as installed by the selected `llvm*`-variant version. I haven't looked at the source code and how difficult that would be, though. -- Ticket URL: <https://trac.macports.org/ticket/51929> MacPorts <https://www.macports.org/> Ports system for OS X