C file in ltsmaster druntime sometimes fails to link on openSUSE with PIE

[bmwiedemann]

When working on reproducible builds for openSUSE, I found that building the ldc package for openSUSE Factory, randomly fails. I got a partial strace file of 80MB showing calls to cmake, make and

[pid 3466159] execve("/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/ldc-0.17.5-src/build/bin/ldc2", ["/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/ldc-0.17.5-src/build/bin/ldc2", "-singleobj", "-g", "-wi", "-O3", "-of=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/build/bin/ldc-prune-cache", "-enable-inlining", "-Hkeep-all-bodies", "-release", "-I=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src", "-I=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/build", "-I=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/dmd", "-J=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/dmd", "-J=/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/res", "-d-version=IN_LLVM", "/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/tools/ldc-prune-cache.d", "/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/driver/cache_pruning.d"], 0x7ffe5e21b5a8 /* 54 vars */ <unfinished ...>

[pid 3466211] execve("/usr/lib64/gcc/x86_64-suse-linux/8/collect2", ["/usr/lib64/gcc/x86_64-suse-linux/8/collect2", "-plugin", "/usr/lib64/gcc/x86_64-suse-linux/8/liblto_plugin.so", "-plugin-opt=/usr/lib64/gcc/x86_64-suse-linux/8/lto-wrapper", "-plugin-opt=-fresolution=/tmp/ccBQvQpg.res", "-plugin-opt=-pass-through=-lgcc", "-plugin-opt=-pass-through=-lgcc_s", "-plugin-opt=-pass-through=-lc", "-plugin-opt=-pass-through=-lgcc", "-plugin-opt=-pass-through=-lgcc_s", "--build-id", "--eh-frame-hdr", "-m", "elf_x86_64", "-dynamic-linker", "/lib64/ld-linux-x86-64.so.2", "-pie", "-o", "/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/build/bin/ldc-prune-cache", "/usr/lib64/gcc/x86_64-suse-linux/8/../../../../lib64/Scrt1.o", "/usr/lib64/gcc/x86_64-suse-linux/8/../../../../lib64/crti.o", "/usr/lib64/gcc/x86_64-suse-linux/8/crtbeginS.o", "-L/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/ldc-0.17.5-src/build/lib", "-L/usr/lib64/gcc/x86_64-suse-linux/8", "-L/usr/lib64/gcc/x86_64-suse-linux/8/../../../../lib64", "-L/lib/../lib64", "-L/usr/lib/../lib64", "-L/usr/lib64/gcc/x86_64-suse-linux/8/../../../../x86_64-suse-linux/lib", "-L/usr/lib64/gcc/x86_64-suse-linux/8/../../..", "/home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/build/bin/ldc-prune-cache.o", "-lphobos2-ldc", "-ldruntime-ldc", "--gc-sections", "-lrt", "-ldl", "-lpthread", "-lm", "-lgcc", "--as-needed", "-lgcc_s", "--no-as-needed", "-lc", "-lgcc", "--as-needed", "-lgcc_s", "--no-as-needed", "/usr/lib64/gcc/x86_64-suse-linux/8/crtendS.o", "/usr/lib64/gcc/x86_64-suse-linux/8/../../../../lib64/crtn.o"], 0x2590fe0 /* 60 vars */) = 0

/lib64/gcc/x86_64-suse-linux/8/../../../../x86_64-suse-linux/bin/ld: /home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/ldc-0.17.5-src/build/lib/libdruntime-ldc.a(errno.c.o): relocation R_X86_64_PC32 against symbol `__errno_location@@GLIBC_2.2.5' can not be used when making a PIE object; recompile with -fPIC

[joakim-noah]

Hmm, -fPIC isn't supplied when building that C file? Should be pretty easy to add that flag, no? That file is actually no longer used in master, been thinking about submitting a pull to remove it.

[kinke]

The C files for druntime/Phobos should all get -fPIC here.
As to why that would fail randomly - absolutely no idea.

[kinke]

Ah, that's ltsmaster failing, which doesn't have that setting. It also doesn't allow for the RT_CFLAGS variable to be set in the CMake cmdline, so that patching this line is probably the way to go.

[bmwiedemann]

I changed ldc-1.10.0-src/runtime/CMakeLists.txt to have

set(RT_CFLAGS             "-fPIC"                                  CACHE STRING "Runtime extra C compiler flags, separated by ' '")

but it still produces such errors. The randomness usually comes from variations in dependency/order when more than 1 rule exists to make a target. E.g. see the example of https://bugzilla.sudo.ws/show_bug.cgi?id=842

[kinke]

I'd suggest switching to ninja; we've had similar issues with make (-G Ninja in CMake command line, then build with ninja).

[bmwiedemann]

ninja does not improve things, so the problem is probably rather with the cmake configs:

[ 1107s] /usr/lib64/gcc/x86_64-suse-linux/8/../../../../x86_64-suse-linux/bin/ld
: /home/abuild/rpmbuild/BUILD/ldc-1.10.0-src/ldc-0.17.5-src/build/lib/libdruntim
e-ldc.a(errno.c.o): relocation R_X86_64_PC32 against symbol `__errno_location@@G
LIBC_2.2.5' can not be used when making a PIE object; recompile with -fPIC
[ 1107s] /usr/lib64/gcc/x86_64-suse-linux/8/../../../../x86_64-suse-linux/bin/ld: final link failed: bad value
[ 1107s] collect2: error: ld returned 1 exit status
[ 1107s] Error: /usr/bin/gcc failed with status: 1
[ 1107s] ninja: build stopped: subcommand failed.

[kinke]

I guess it's both (the make troubles don't apply to ltsmaster, but to master). - You 'need' to adapt the 0.17.5/ltsmaster CMake config, not 1.10/master's, which should already default to -fPIC as mentioned earlier.