Re: Libtool does not detect statically linked internal compiler libraries

[Manoj Gupta]

There is also a similar problem when using clang's compiler-rt for builtins. In that case, the internal library is /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.builtins-x86_64.a. 

Mesa graphics library links some libraries with -nostdlib option and relies on libtool to supply the internal libraries on the command line. Since libtool didn't find the compiler-rt builtin libarry, linking fails :(  

clang++ -rtlib=compiler-rt main.cpp -v

Linker command line:

 "/usr/bin/x86_64-pc-linux-gnu-ld" --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crt1.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crti.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/crtbegin.o -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64 -L/usr/bin/../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../x86_64-pc-linux-gnu/lib -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../.. -L/usr/bin/../lib -L/lib -L/usr/lib /tmp/dtoul-6b0bb5.o -lc++ -lm /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.builtins-x86_64.a -lgcc_eh -lc /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.builtins-x86_64.a -lgcc_eh /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/crtend.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crtn.o

Thanks,

Manoj

On Wed, Jul 26, 2017 at 7:41 PM, Manoj Gupta <address@hidden> wrote:

Hi,

We are trying to use clang with address sanitizer in one of the projects. However, there are build issues because libtool's internal compiler library detection part does not work with static libraries. 

e.g. clang++ main.cpp -fsanitize=address -v shows the use of static library /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.asan-x86_64.a

Looking at the source code at http://git.savannah.gnu.org/cgit/libtool.git/tree/m4/libtool.m4#n7556 , libtool does not handle use of static libraries.

dnl Parse the compiler output and extract the necessary
dnl objects, libraries and library flags.
if AC_TRY_EVAL(ac_compile); then
  # Parse the compiler output and extract the necessary
  # objects, libraries and library flags.

  # Sentinel used to keep track of whether or not we are before
  # the conftest object file.
  pre_test_object_deps_done=no

  for p in `eval "$output_verbose_link_cmd"`; do
    case $prev$p in

  for p in `eval "$output_verbose_link_cmd"`; do
    case $prev$p in

    -L* | -R* | -l*) // Adding *.a here should handle static library

Is it possible for libtool to handle this case?

Linker command line (from the above clang invocation):

/usr/bin/x86_64-pc-linux-gnu-ld" --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crt1.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crti.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/crtbegin.o -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64 -L/usr/bin/../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../x86_64-pc-linux-gnu/lib -L/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../.. -L/usr/bin/../lib -L/lib -L/usr/lib -whole-archive /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.asan-x86_64.a -no-whole-archive --dynamic-list=/usr/lib64/clang/5.0.0/lib/linux/libclang_rt.asan-x86_64.a.syms -whole-archive /usr/lib64/clang/5.0.0/lib/linux/libclang_rt.asan_cxx-x86_64.a -no-whole-archive --dynamic-list=/usr/lib64/clang/5.0.0/lib/linux/libclang_rt.asan_cxx-x86_64.a.syms /tmp/main-0d221f.o -lc++ -lm --no-as-needed -lpthread -lrt -lm -ldl -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/crtend.o /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/4.9.x/../../../../lib64/crtn.o

Thanks,

Manoj