dwfl_module_getsrc() doesn't work unexpectedly if the target
executable is compiled with clang though it works well with an
executable compiled with gcc.

For testing I used executables built from the following source code (target.c):

    static int
    f1(void)
    {
      while (1);
      return 0;
    }

    static int
    f0(void)
    {
      return f1();
    }

    int main(void)
    {
      return f0();
    }

I made two executables with two compilers.
  $ gcc -O0 -g target.c -o target-gcc
  $ clang -O0 -g target.c -o target-clang

I run the two executables in background:

    $ ./target-gcc &  
    [2] 2118229

    $ ./target-clang &         
    [3] 2118253

I run src/stack with -s -p options:


For the executable built with gcc, backtrace reported source lines.

    $ ./src/stack -s -p 2118229
    PID 2118229 - process
    TID 2118229:
    #0  0x000000000040110a f1
	/home/yamato/var/elfutils/tests/target.c:4:9
    #1  0x0000000000401115 f0
	/home/yamato/var/elfutils/tests/target.c:11:10
    #2  0x0000000000401120 main
	/home/yamato/var/elfutils/tests/target.c:16:10
    #3  0x00007f7d6c823b8a __libc_start_call_main
	../sysdeps/nptl/libc_start_call_main.h:58:16
    #4  0x00007f7d6c823c4b __libc_start_main@@GLIBC_2.34
	../csu/libc-start.c:360:3
    #5  0x0000000000401045 _start


For the executable built with clang, backtrace didn't report source lines.

    $ ./src/stack -s -p 2118253
    PID 2118253 - process
    TID 2118253:
    #0  0x0000000000401149 f1
    #1  0x0000000000401139 f0
    #2  0x0000000000401124 main
    #3  0x00007f4a84ab5b8a __libc_start_call_main
	../sysdeps/nptl/libc_start_call_main.h:58:16
    #4  0x00007f4a84ab5c4b __libc_start_main@@GLIBC_2.34
	../csu/libc-start.c:360:3
    #5  0x0000000000401045 _start

The bt command of Gdb can report them:

    $ ./target-clang &
    [1] 2116805
    [yamato@dev64]~/var/elfutils/tests% pstack 2116805
    #0  0x0000000000401149 in f1 () at target.c:4
    #1  0x0000000000401139 in f0 () at target.c:11
    #2  0x0000000000401124 in main () at target.c:16

Gdb can report the source lines. So I guess clang injected enough information
to the executable.

The versions of the compilers:
    $ gcc -v
    Using built-in specs.
    COLLECT_GCC=gcc
    COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/13/lto-wrapper
    OFFLOAD_TARGET_NAMES=nvptx-none
    OFFLOAD_TARGET_DEFAULT=1
    Target: x86_64-redhat-linux
    Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,m2,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --enable-libstdcxx-backtrace --with-libstdcxx-zoneinfo=/usr/share/zoneinfo --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl=/builddir/build/BUILD/gcc-13.2.1-20230728/obj-x86_64-redhat-linux/isl-install --enable-offload-targets=nvptx-none --without-cuda-driver --enable-offload-defaulted --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux --with-build-config=bootstrap-lto --enable-link-serialization=1
    Thread model: posix
    Supported LTO compression algorithms: zlib zstd
    gcc version 13.2.1 20230728 (Red Hat 13.2.1-1) (GCC)
    
    $ clang -v
    clang version 16.0.6 (Fedora 16.0.6-3.fc38)
    Target: x86_64-redhat-linux-gnu
    Thread model: posix
    InstalledDir: /usr/bin
    Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/13
    Selected GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/13
    Candidate multilib: .;@m64
    Candidate multilib: 32;@m32
    Selected multilib: .;@m64

The revision of elfutils: 557aa6a4b7b1d678b7c2c3b9aae1dafcc2160c64 (git commit).