link failure of gdb with non-gcc compiler

[Bruno Haible]

Bulding gdb-6.4 on Linux/x86 with Sun C 5.9 finally also leads to a static
executable, because "-rdynamic" with this compiler is unsupported:

cc: Warning: illegal option -dynamic

and leads to a statically linked executable (undocumented behaviour).
Instead, for this compiler, the equivalent option is -Wl,--export-dynamic.

Here is a fix, choosing the right option to use in configure.ac. (Btw,
this patch uses the option --export-dynamic of GNU ld. I don't understand
why the Solaris handling in configure.ac uses the option -export-dynamic.
This is *not* a documented option of GNU ld.)


2006-05-07  Bruno Haible  <address@hidden>

        Make it possible to use a non-gcc compiler on Linux/x86.
        * configure.ac (EXPORT_DYNAMIC) [linux]: New variable.
        * config/i386/linux.mh (LOADLIBES): Use it.

*** gdb-6.4/gdb/configure.ac.bak        2005-07-25 17:08:40.000000000 +0200
--- gdb-6.4/gdb/configure.ac    2006-05-07 19:19:26.000000000 +0200
***************
*** 1019,1024 ****
--- 1019,1053 ----
           AC_MSG_RESULT(no)
        fi
        ;;
+    linux*)
+       # The GNU linker requires the --export-dynamic option to make
+       # all symbols visible in the dynamic symbol table.  But the option
+       # to pass depends on the compiler.
+       if test "$GCC" = "yes" ; then
+          EXPORT_DYNAMIC="-rdynamic"
+       else
+          # Try "-rdynamic" and "-Wl,--export-dynamic".
+          AC_MSG_CHECKING([for the -rdynamic flag])
+          saved_ldflags=$LDFLAGS
+          LDFLAGS="${LDFLAGS} -ldl -rdynamic"
+          AC_TRY_RUN([#include <dlfcn.h>
+                      #include <stddef.h>
+                      int foo () { return 42; }
+                      int main ()
+                      {
+                        return (dlsym (NULL, "foo") == NULL);
+                      }],
+                     found=yes, found=no)
+          LDFLAGS=$saved_ldflags
+          AC_MSG_RESULT($found)
+          if test $found = yes; then
+             EXPORT_DYNAMIC="-rdynamic"
+          else
+             EXPORT_DYNAMIC="-Wl,--export-dynamic"
+          fi
+       fi
+       AC_SUBST([EXPORT_DYNAMIC])
+       ;;
     aix*)
        AC_MSG_CHECKING(for AiX thread debugging library)
        AC_CACHE_VAL(gdb_cv_have_aix_thread_debug,
*** gdb-6.4/gdb/config/i386/linux.mh.bak        2005-09-10 20:11:10.000000000 
+0200
--- gdb-6.4/gdb/config/i386/linux.mh    2006-05-07 19:09:08.000000000 +0200
***************
*** 8,11 ****
  
  # The dynamically loaded libthread_db needs access to symbols in the
  # gdb executable.
! LOADLIBES = -ldl -rdynamic
--- 8,11 ----
  
  # The dynamically loaded libthread_db needs access to symbols in the
  # gdb executable.
! LOADLIBES = -ldl @EXPORT_DYNAMIC@