Checking for -rdynamic flag in gcc/configure

[Steve Ellcey <sje at cup dot hp dot com>]

I have a question about the check for -rdynamic in gcc/configure.
What we have in configure.ac is:

  # Check -rdynamic
  LDFLAGS="$LDFLAGS -rdynamic"
  AC_MSG_CHECKING([for -rdynamic])
  AC_TRY_LINK([],[return 0;],
    [AC_MSG_RESULT([yes]); have_rdynamic=yes],
    [AC_MSG_RESULT([no])])
  if test x"$have_rdynamic" = x"yes" ; then
    pluginlibs="-rdynamic"
  fi

The problem I have is that on HP-UX this test will set have_rdynamic
to yes even though the HP linker doesn't understand the option.
The AC_TRY_LINK works because the linker prints a warning message
about not understanding -rdynamic but still runs and creates an
object file.  Thus the configure script thinks the HP linker does
know about the -rdynamic flag and continues to use it (resulting
in more warnings during the GCC build).

Any ideas on how to address this?

Steve Ellcey
sje@cup.hp.com