http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59469
--- Comment #43 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- Created attachment 32045 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32045&action=edit new testcase r207489 fixes the original issue. Thanks. But llvm still doesn't build with -flto: FAILED: : && /usr/bin/g++ -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -pedantic -Wno-long-long -Wno-may be-uninitialized -Wnon-virtual-dtor -fno-rtti -O3 -DNDEBUG -pipe -march=native -flto=4 -Wl,-O1,--hash-style=gnu,--as-needed,--gc-sections,--icf=all,--icf-iterations=3 utils/ FileCheck/CMakeFiles/FileCheck.dir/FileCheck.cpp.o -o bin/FileCheck -lrt -ldl -lcurses -lpthread -lz lib/libLLVMSupport.so -lpthread -lrt -ldl -lcurses -lpthread -lz -Wl,-r path,/var/tmp/llvm_build/lib && : lib/libLLVMSupport.so: error: undefined reference to 'void* llvm::object_creator<llvm::StringMap<llvm::Timer, llvm::MallocAllocator> >()' lib/libLLVMSupport.so: error: undefined reference to 'void* llvm::object_creator<std::string>()' lib/libLLVMSupport.so: error: undefined reference to 'void* llvm::object_creator<std::vector<llvm::Timer*, std::allocator<llvm::Timer*> > >()' collect2: error: ld returned 1 exit status ninja: build stopped: subcommand failed. In this case lto produces an undefined symbol for e.g.: 42902 static ManagedStatic<std::vector<Timer*> > ActiveTimers; Before r207489 the symbol was weak. markus@x4 llvm_build % g++ -fPIC -O3 -flto -shared Timer.ii markus@x4 llvm_build % nm a.out | grep _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv U _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv markus@x4 llvm_build % g++ -fPIC -O3 -flto -flto-partition=none -shared Timer.ii markus@x4 llvm_build % nm a.out | grep _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv 0000000000003770 W _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv markus@x4 llvm_build % g++ -fPIC -O3 -shared Timer.ii markus@x4 llvm_build % nm a.out | grep _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv 0000000000008dc0 W _ZN4llvm14object_creatorISt6vectorIPNS_5TimerESaIS3_EEEEPvv markus@x4 llvm_build %
