Is this expected behaviour?

[elsandosgrande]

Since I'm not sure if this is a mold bug or not and because I haven't double-checked things, I'm asking here in Discussions. Basically, I'm running Gentoo (~amd64) and, in the process of preparing to switch to Clang as my global compiler, I have been compiling certain packages with it before I go ahead and rebuild the world set with --emptytree, including the problematic package, dev-util/intel-graphics-compiler-1.0.13860.4. As far as I can tell, and I'm probably wrong, mold doesn't seem to properly understand -Wl,-undefined:

[…]
[479/905] : && /usr/lib/llvm/16/bin/clang++-16 -fPIC -march=native -pipe -g3 -flto=thin -fno-common -fwhole-program-vtables -fdebug-types-section -fasynchronous-unwind-tables -fstack-clash-protection -fstack-protector-strong -fvisibility-inlines-hidden -frecord-gcc-switches -fno-function-sections -fno-data-sections -mllvm -polly -mllvm -polly-vectorizer=stripmine -U_GLIBCXX_ASSERTIONS -fexceptions -O2 -fmessage-length=0 -march=corei7 -mstackrealign -fms-extensions -Wno-unused-parameter -Wno-missing-field-initializers -Wwrite-strings -Wno-long-long -Wswitch -Wno-sign-compare -Wno-unused-result -Wno-enum-compare -Wno-type-limits -Wno-ignored-qualifiers -Wno-shadow -Wformat -Wformat-security -Wno-extra -Wno-write-strings -finline -fno-strict-aliasing -msse -msse2 -msse3 -mssse3 -msse4 -msse4.1 -msse4.2 -Wno-unknown-pragmas -fPIC -Bsymbolic -fstack-protector -finline-functions -fno-rtti -fvisibility=hidden -g  -Wl,-O1 -Wl,--as-needed -Wl,--no-gc-sections -Wl,-O2 -fuse-ld=mold -march=native -pipe -g3 -O3 -flto=thin -fno-common -fwhole-program-vtables -fdebug-types-section -fasynchronous-unwind-tables -fstack-clash-protection -fstack-protector-strong -fvisibility-inlines-hidden -frecord-gcc-switches -fno-function-sections -fno-data-sections -mllvm -polly -mllvm -polly-vectorizer=stripmine -Wl,-z,undefs -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -shared -Wl,-undefined,dynamic_lookup -Wl,-headerpad_max_install_names -g -Wl,--gc-sections -shared -Wl,-soname,libigdfcl.so.1 -o IGC/Release/libigdfcl.so.1.0.1 IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_dll.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_tb.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_debug.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/LoadBuffer.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/CLElfLib/ElfReader.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/CLElfLib/ElfWriter.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/builtins/memory/buffer/impl/buffer_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/builtins/builtins_registry.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/export/cif_main.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/export/registry.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/fcl_ocl_translation_ctx_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/fcl_ocl_device_ctx_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/ocl_translation_output_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/platform_impl.cpp.o  -Wl,-rpath,/usr/lib/llvm/15/lib64:  -Wl,--whole-archive  IGC/Release/libCTHLibFcl.a  -Wl,--no-whole-archive  -Wl,--start-group  /usr/lib/llvm/15/lib64/liblldELF.so  -Wl,--end-group  /usr/lib/llvm/15/lib64/libopencl-clang.so  -ldl  /usr/lib/llvm/15/lib64/liblldCommon.so  /usr/lib64/libz.so  /usr/lib/llvm/15/lib64/libLLVM-15.so && :
FAILED: IGC/Release/libigdfcl.so.1.0.1 
: && /usr/lib/llvm/16/bin/clang++-16 -fPIC -march=native -pipe -g3 -flto=thin -fno-common -fwhole-program-vtables -fdebug-types-section -fasynchronous-unwind-tables -fstack-clash-protection -fstack-protector-strong -fvisibility-inlines-hidden -frecord-gcc-switches -fno-function-sections -fno-data-sections -mllvm -polly -mllvm -polly-vectorizer=stripmine -U_GLIBCXX_ASSERTIONS -fexceptions -O2 -fmessage-length=0 -march=corei7 -mstackrealign -fms-extensions -Wno-unused-parameter -Wno-missing-field-initializers -Wwrite-strings -Wno-long-long -Wswitch -Wno-sign-compare -Wno-unused-result -Wno-enum-compare -Wno-type-limits -Wno-ignored-qualifiers -Wno-shadow -Wformat -Wformat-security -Wno-extra -Wno-write-strings -finline -fno-strict-aliasing -msse -msse2 -msse3 -mssse3 -msse4 -msse4.1 -msse4.2 -Wno-unknown-pragmas -fPIC -Bsymbolic -fstack-protector -finline-functions -fno-rtti -fvisibility=hidden -g  -Wl,-O1 -Wl,--as-needed -Wl,--no-gc-sections -Wl,-O2 -fuse-ld=mold -march=native -pipe -g3 -O3 -flto=thin -fno-common -fwhole-program-vtables -fdebug-types-section -fasynchronous-unwind-tables -fstack-clash-protection -fstack-protector-strong -fvisibility-inlines-hidden -frecord-gcc-switches -fno-function-sections -fno-data-sections -mllvm -polly -mllvm -polly-vectorizer=stripmine -Wl,-z,undefs -Wl,--no-undefined -Wl,-z,noexecstack -Wl,-z,relro -Wl,-z,now -shared -Wl,-undefined,dynamic_lookup -Wl,-headerpad_max_install_names -g -Wl,--gc-sections -shared -Wl,-soname,libigdfcl.so.1 -o IGC/Release/libigdfcl.so.1.0.1 IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_dll.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_tb.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/clang_debug.cpp.o IGC/CMakeFiles/fcl_dll.dir/OCLFE/igd_fcl_mcl/source/LoadBuffer.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/CLElfLib/ElfReader.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/CLElfLib/ElfWriter.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/builtins/memory/buffer/impl/buffer_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/builtins/builtins_registry.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/export/cif_main.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/cif/cif/export/registry.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/fcl_ocl_translation_ctx_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/fcl_ocl_device_ctx_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/ocl_translation_output_impl.cpp.o IGC/CMakeFiles/fcl_dll.dir/AdaptorOCL/ocl_igc_interface/impl/platform_impl.cpp.o  -Wl,-rpath,/usr/lib/llvm/15/lib64:  -Wl,--whole-archive  IGC/Release/libCTHLibFcl.a  -Wl,--no-whole-archive  -Wl,--start-group  /usr/lib/llvm/15/lib64/liblldELF.so  -Wl,--end-group  /usr/lib/llvm/15/lib64/libopencl-clang.so  -ldl  /usr/lib/llvm/15/lib64/liblldCommon.so  /usr/lib64/libz.so  /usr/lib/llvm/15/lib64/libLLVM-15.so && :
clang-16: warning: argument unused during compilation: '-mllvm -polly' [-Wunused-command-line-argument]
clang-16: warning: argument unused during compilation: '-mllvm -polly-vectorizer=stripmine' [-Wunused-command-line-argument]
clang-16: warning: argument unused during compilation: '-mllvm -polly' [-Wunused-command-line-argument]
clang-16: warning: argument unused during compilation: '-mllvm -polly-vectorizer=stripmine' [-Wunused-command-line-argument]
mold: fatal: cannot open dynamic_lookup: No such file or directory
clang-16: error: linker command failed with exit code 1 (use -v to see invocation)
[…]

I'll later try using lld as the linker and report back. I don't recall having this issue with GCC, but the package was last built in on the 24th of April this year, at which point I don't think I even knew of mold, so it probably went smoothly due to me using GNU ld with GCC.

Have a nice day!

Edit

It linked fine with lld.

[rui314]

There is a single-letter option -u that takes an argument, so -u<foo> is interpreted as -u <foo>. In your case, it's interpreted as -u ndefined. If you want to specify the --undefined option, you need to prepend it with double dashes (i.e. pass -Wl,--undefined).

[elsandosgrande]

I'm not the one specifying the option though, the package is 🥲. I'll try making a patch later and then see even later if upstream will accept it.

[rui314]

I still think that it is very inconsistent to handle -u<something> as a synonym for --undefined only if <something> is ndefined, but in practice, compatibility with other linkers matters. Let me make a change to the mold side.

[rui314]

Fixed in 2d25a93

[elsandosgrande]

Awesome and thank you for the fix!

[MaskRay]

This is probably a case where lld can drop -undefined and keep just --undefined. I think the user should switch to -Wl,-u or -Wl,-undefined

[rui314]

I guess the last one is a typo of -Wl,--undefined? Anyways, that's what I thought, but it looks like there are too many programs that are (erroneously) using the -Wl,-undefined option.