Thunderbird fails to link on trusty/i386 with the following error:
/<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/_virtualenv/bin/python /<<BUILDDIR>>/thunderbird-52.1.0+build2/mozilla/config/expandlibs_exec.py --uselist -- /usr/bin/g++ -std=gnu++11 -Wall -Wc++11-compat -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wwrite-strings -Wno-invalid-offsetof -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -fno-exceptions -fno-strict-aliasing -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -g -freorder-blocks -Os -fomit-frame-pointer -fPIC -shared -Wl,-z,defs -Wl,--gc-sections -Wl,-h,libprldap60.so -o libprldap60.so ldappr-dns.o ldappr-error.o ldappr-io.o ldappr-public.o ldappr-threads.o -lpthread -Wl,-z,noexecstack -Wl,-z,text -Wl,--build-id -Wl,-rpath-link,/<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/dist/bin -Wl,-rpath-link,/usr/lib ../../../../config/external/nspr/libnspr.a ../../../../ldap/c-sdk/libraries/libldap/libldap60.so ../../../../config/external/nspr/pr/libnspr4.so ../../../../config/external/nspr/libc/libplc4.so ../../../../config/external/nspr/ds/libplds4.so -ldl
Executing: /usr/bin/g++ -std=gnu++11 -Wall -Wc++11-compat -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wsign-compare -Wtype-limits -Wunreachable-code -Wwrite-strings -Wno-invalid-offsetof -Wno-error=maybe-uninitialized -Wno-error=deprecated-declarations -Wno-error=array-bounds -fno-exceptions -fno-strict-aliasing -fno-rtti -ffunction-sections -fdata-sections -fno-exceptions -fno-math-errno -pthread -pipe -g -freorder-blocks -Os -fomit-frame-pointer -fPIC -shared -Wl,-z,defs -Wl,--gc-sections -Wl,-h,libprldap60.so -o libprldap60.so /<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/ldap/c-sdk/libraries/libprldap/tmpPoM9m_.list -lpthread -Wl,-z,noexecstack -Wl,-z,text -Wl,--build-id -Wl,-rpath-link,/<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/dist/bin -Wl,-rpath-link,/usr/lib ../libldap/libldap60.so ../../../../config/external/nspr/pr/libnspr4.so ../../../../config/external/nspr/libc/libplc4.so ../../../../config/external/nspr/ds/libplds4.so -ldl
/<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/ldap/c-sdk/libraries/libprldap/tmpPoM9m_.list:
INPUT("ldappr-dns.o")
INPUT("ldappr-error.o")
INPUT("ldappr-io.o")
INPUT("ldappr-public.o")
INPUT("ldappr-threads.o")
/usr/lib/i386-linux-gnu/libc_nonshared.a(stack_chk_fail_local.oS): In function `__stack_chk_fail_local':
(.text+0x10): undefined reference to `__stack_chk_fail'
collect2: error: ld returned 1 exit status
make[5]: *** [libprldap60.so] Error 1
make[5]: Leaving directory `/<<BUILDDIR>>/thunderbird-52.1.0+build2/obj-i686-linux-gnu/ldap/c-sdk/libraries/libprldap'
make[4]: *** [ldap/c-sdk/libraries/libprldap/target] Error 2
make[4]: *** Waiting for unfinished jobs....
I've worked around this in the past by exporting "LIBS=-lc", but without really understanding what the issue is. So I've taken a proper look at this issue now.
Firstly, "-lc" is passed to the linker without the previous workaround. This can be observed by adding --verbose to the link command:
/usr/lib/gcc/i686-linux-gnu/4.8/collect2 --sysroot=/ --build-id --eh-frame-hdr -m elf_i386 --hash-style=gnu --as-needed -shared -z relro -o libprldap60.so /usr/lib/gcc/i686-linux-gnu/4.8/../../../i386-linux-gnu/crti.o /usr/lib/gcc/i686-linux-gnu/4.8/crtbeginS.o -L/usr/lib/gcc/i686-linux-gnu/4.8 -L/usr/lib/gcc/i686-linux-gnu/4.8/../../../i386-linux-gnu -L/usr/lib/gcc/i686-linux-gnu/4.8/../../../../lib -L/lib/i386-linux-gnu -L/lib/../lib -L/usr/lib/i386-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/i686-linux-gnu/4.8/../../.. -z defs --gc-sections -h libprldap60.so /build/thunderbird-52.1.1+build1/obj-i686-linux-gnu/ldap/c-sdk/libraries/libprldap/tmpPrXe8H.list -lpthread -z noexecstack -z text --build-id -rpath-link /build/thunderbird-52.1.1+build1/obj-i686-linux-gnu/dist/bin -rpath-link /usr/lib ../libldap/libldap60.so ../../../../config/external/nspr/pr/libnspr4.so ../../../../config/external/nspr/libc/libplc4.so ../../../../config/external/nspr/ds/libplds4.so -ldl -lstdc++ -lm -lgcc_s -lpthread -lc -lgcc_s /usr/lib/gcc/i686-linux-gnu/4.8/crtendS.o /usr/lib/gcc/i686-linux-gnu/4.8/../../../i386-linux-gnu/crtn.o
The workaround results in "-lc" being passed twice.
Passing "-Wl,--verbose" to the link command shows that ld loads libc.so from /usr/lib/i386-linux-gnu/libc.so. This is actually a linker script containing the following line:
GROUP ( /lib/i386-linux-gnu/libc.so.6 /usr/lib/i386-linux-gnu/libc_nonshared.a AS_NEEDED ( /lib/i386-linux-gnu/ld-linux.so.2 ) )
So the linker first loads the real libc.so.6. However, none of the object files that we are linking use any symbols exported from libc. Because our default configuration is to link with --as-needed, this means that libc.so is dropped now and is not used for further symbol resolution. Then we load libc_nonshared.a, from which we require stack_chk_fail_local.oS. This contains a call to stack_chk_fail, which is exported from libc. The link now fails because it can't resolve the call to stack_chk_fail.
It seems like libc_nonshared.a should come before libc.so.6.
I can reproduce this with the attached C++ file (build commands are included at the top). If I remove -Wl,-z,defs from the test case, I get a .so without any DT_NEEDED entries
Subscribing doko, as I'm not sure if there's a subtle glibc bug here (with the ordering of libraries in the libc.so linker script).
I can only reproduce this on trusty's toolchain in any case, so not particularly important. And only on x86 (the compiler doesn't appear to emit calls to stack_chk_