https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68650
--- Comment #4 from Georg Koppen <gk at torproject dot org> ---
It is using -lasan it seems:
Executing: c++ -o firefox -Wall -Wempty-body -Woverloaded-virtual
-Wsign-compare -Wwrite-strings -Wno-invalid-offsetof -Wcast-align -v
-fsanitize=address -Dxmalloc=myxmalloc -fno-exceptions -fno-strict-aliasing
-fno-rtti -fno-exceptions -fno-math-errno -std=gnu++0x -pthread -pipe -DNDEBUG
-DTRIMMED -g -freorder-blocks -Os -fno-omit-frame-pointer
/home/thomas/Arbeit/Tor/mozilla-central/obj-x86_64-unknown-linux-gnu/browser/app/tmpjOe32q.list
-lpthread -fsanitize=address -Wl,-z,noexecstack -Wl,-z,text -Wl,--build-id -B
../../build/unix/gold -Wl,-Bsymbolic -rdynamic
-Wl,-rpath-link,/home/thomas/Arbeit/Tor/mozilla-central/obj-x86_64-unknown-linux-gnu/dist/bin
-Wl,-rpath-link,NONE/lib ../../xpcom/glue/standalone/libxpcomglue.a
/home/thomas/Arbeit/Tor/mozilla-central/obj-x86_64-unknown-linux-gnu/browser/app/tmpjOe32q.list:
INPUT("nsBrowserApp.o")
INPUT("../../mozglue/build/AsanOptions.o")
INPUT("../../mozglue/build/SSE.o")
INPUT("../../mozglue/build/dummy.o")
INPUT("../../memory/mozalloc/Unified_cpp_memory_mozalloc0.o")
INPUT("../../mozglue/misc/StackWalk.o")
INPUT("../../mozglue/misc/TimeStamp.o")
INPUT("../../mozglue/misc/TimeStamp_posix.o")
INPUT("../../mfbt/Compression.o")
INPUT("../../mfbt/Decimal.o")
INPUT("../../mfbt/Unified_cpp_mfbt0.o")
INPUT("../../memory/fallible/fallible.o")
Using built-in specs.
COLLECT_GCC=c++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 5.2.1-23'
--with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 5.2.1 20151028 (Debian 5.2.1-23)
COMPILER_PATH=../../build/unix/gold/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=../../build/unix/gold/:/usr/lib/gcc/x86_64-linux-gnu/5/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/5/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-o' 'firefox' '-Wall' '-Wempty-body'
'-Woverloaded-virtual' '-Wsign-compare' '-Wwrite-strings'
'-Wno-invalid-offsetof' '-Wcast-align' '-v' '-fsanitize=address' '-D'
'xmalloc=myxmalloc' '-fno-strict-aliasing' '-fno-rtti' '-fno-exceptions'
'-fno-math-errno' '-std=gnu++11' '-pthread' '-pipe' '-D' 'NDEBUG' '-D'
'TRIMMED' '-g' '-freorder-blocks' '-Os' '-fno-omit-frame-pointer'
'-fsanitize=address' '-B' '../../build/unix/gold' '-rdynamic' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/5/collect2 -plugin
/usr/lib/gcc/x86_64-linux-gnu/5/liblto_plugin.so
-plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
-plugin-opt=-fresolution=/tmp/ccNcaQre.res -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lpthread
-plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc --sysroot=/ --build-id --eh-frame-hdr -m
elf_x86_64 --hash-style=gnu -export-dynamic -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -o firefox
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crti.o
/usr/lib/gcc/x86_64-linux-gnu/5/crtbegin.o -L../../build/unix/gold
-L/usr/lib/gcc/x86_64-linux-gnu/5
-L/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/5/../../../../lib -L/lib/x86_64-linux-gnu
-L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib
-L/usr/lib/gcc/x86_64-linux-gnu/5/../../..
/usr/lib/gcc/x86_64-linux-gnu/5/libasan_preinit.o -lasan
/home/thomas/Arbeit/Tor/mozilla-central/obj-x86_64-unknown-linux-gnu/browser/app/tmpjOe32q.list
-lpthread -z noexecstack -z text --build-id -Bsymbolic -rpath-link
/home/thomas/Arbeit/Tor/mozilla-central/obj-x86_64-unknown-linux-gnu/dist/bin
-rpath-link NONE/lib ../../xpcom/glue/standalone/libxpcomglue.a -lstdc++ -lm
-lgcc_s -lgcc -lpthread -lc -lgcc_s -lgcc
/usr/lib/gcc/x86_64-linux-gnu/5/crtend.o
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crtn.o
/home/thomas/Arbeit/Tor/mozilla-central/xpcom/glue/standalone/nsXPCOMGlue.cpp:167:
error: undefined reference to 'dlerror'
