# Git fails to build on Ubuntu Server 16.04 2 messages from 2017-03-28 to 2017-03-29. Participants: Jeffrey Walton, Jeff King. Thread: https://gitlist.dev/t/45531 ## Jeffrey Walton, 2017-03-28 23:17 Subject: Git fails to build on Ubuntu Server 16.04 Message-ID: URL: https://gitlist.dev/e/CAH8yC8kexrV8d7Tg_vCCM%2BGWsNH82386HEyN%3DXSguqZjcOuPzQ%40mail.gmail.com ``` I configured with --enable-pthreads, and LIBS included -lpthread. $ make V=1 gcc -I/usr/local/include -g -O2 -I. -DHAVE_ALLOCA_H -I/usr/local/include -DUSE_CURL_FOR_IMAP_SEND -I/usr/local/include -I/usr/local/include -DHAVE_PATHS_H -DHAVE_STRINGS_H -DHAVE_DEV_TTY -DHAVE_CLOCK_GETTIME -DHAVE_CLOCK_MONOTONIC -DHAVE_GETDELIM -DSHA1_HEADER='' -DNO_STRLCPY -DSHELL_PATH='"/bin/sh"' -DPAGER_ENV='"LESS=FRX LV=-c"' -o git-credential-store -Wl,-rpath,/usr/local/lib -L/usr/local/lib credential-store.o common-main.o libgit.a xdiff/lib.a -L/usr/local/lib -Wl,-rpath,/usr/local/lib -lz -L/usr/local/lib -Wl,-rpath,/usr/local/lib -lcrypto -lrt /usr/bin/ld: libgit.a(run-command.o): undefined reference to symbol 'pthread_sigmask@@GLIBC_2.2.5' //lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line collect2: error: ld returned 1 exit status Makefile:2053: recipe for target 'git-credential-store' failed make: *** [git-credential-store] Error 1 If the makefile is modified after 'make configure': find `pwd` -name Makefile -exec sed -i 's|-lrt|-lrt -lpthread|g' {} \; Then Git builds successfully. It appears the request to use pthreads is not being honored. Thanks. ``` ## Jeff King, 2017-03-29 03:18 Subject: Re: Git fails to build on Ubuntu Server 16.04 Message-ID: <20170329031836.h2j3hja4ktocbv6i@sigill.intra.peff.net> URL: https://gitlist.dev/e/20170329031836.h2j3hja4ktocbv6i%40sigill.intra.peff.net In-Reply-To: ``` On Tue, Mar 28, 2017 at 07:17:16PM -0400, Jeffrey Walton wrote: > I configured with --enable-pthreads, and LIBS included -lpthread. > > $ make V=1 > gcc -I/usr/local/include -g -O2 -I. -DHAVE_ALLOCA_H > -I/usr/local/include -DUSE_CURL_FOR_IMAP_SEND -I/usr/local/include > -I/usr/local/include -DHAVE_PATHS_H -DHAVE_STRINGS_H -DHAVE_DEV_TTY > -DHAVE_CLOCK_GETTIME -DHAVE_CLOCK_MONOTONIC -DHAVE_GETDELIM > -DSHA1_HEADER='' -DNO_STRLCPY -DSHELL_PATH='"/bin/sh"' > -DPAGER_ENV='"LESS=FRX LV=-c"' -o git-credential-store > -Wl,-rpath,/usr/local/lib -L/usr/local/lib credential-store.o > common-main.o libgit.a xdiff/lib.a -L/usr/local/lib > -Wl,-rpath,/usr/local/lib -lz -L/usr/local/lib > -Wl,-rpath,/usr/local/lib -lcrypto -lrt > /usr/bin/ld: libgit.a(run-command.o): undefined reference to symbol > 'pthread_sigmask@@GLIBC_2.2.5' > //lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO > missing from command line > collect2: error: ld returned 1 exit status > Makefile:2053: recipe for target 'git-credential-store' failed > make: *** [git-credential-store] Error 1 Hmm. I can reproduce with: LIBS=-lpthread ./configure --enable-pthreads make I think the problem is that $LIBS is meaningful to autoconf, but not to Git's Makefile. So it tricks autoconf into writing a blank PTHREAD_LIBS variable (because it can compile a pthread program without any extra options), but the Makefile does not include $LIBS. Just doing: ./configure --enable-pthreads make works fine. So should: ./configure make which should detect pthreads. Or just: make as building with pthreads is the default on Linux. So depending on your perspective, it's either: - not a bug (because we do not advertise $LIBS as a meaningful input to the build process) - a bug that the configure script respects $LIBS at all, since it is not meaningful to the Makefile - a bug that the configure script does not propagate $LIBS into something the Makefile _does_ understand, like $EXTLIBS - a bug that the Makefile does not care about $LIBS Patches welcome for any of the latter three (I do not have an opinion myself; I don't use autoconf at all). -Peff ```