RFA/RFC: Using weak symbols to work around missing newlib math functions in gcc.dg tests

[Nick Clifton]

Hi Guys,

  I made a change to the dejagnu test harness recently that made
  newlib header files be included via the -isystem command line switch
  and not the -I switch.  This broke the gcc.dg/builtins-18.c and
  gcc/dg/builtins-20.c tests for targets that use newlib:

    http://gcc.gnu.org/ml/gcc-patches/2004-11/msg00881.html
    http://sources.redhat.com/ml/binutils/2004-11/msg00258.html

  Although I believe that the patch itself was correct - newlib header
  files are system header files and should be treated as such -
  Richard Earnshaw asked if I could find a way to restore the search
  path ordering such that when builtins-config.h includes <limits.h> it
  gets the version in newlib and not the version in gcc/include.  This
  was cause of the new testsuite breakages because the <limits.h> in
  gcc/include does not define _NEWLIB_VERSION and so builtins-config,h
  defines HAVE_C99_RUNTIME which then leads to linkage errors.

  I have not been able to find a way to restore the search path
  ordering.  GCC places gcc/include before all paths specified by the
  -isystem switch, as this is necessary for the fixincludes system to
  work.  I think that this is the correct behaviour and that we do not
  want the newlib include directory to be searched before the gcc
  include directory.  Instead I believe that we need to fix the
  builtin tests in the gcc.dg testsuite.

  In my opinion it is wrong for builtins-config.h to rely upon
  <limits.h> defining _NEWLIB_VERSION, precisely because of this
  fixincludes behaviour.  Instead I feel that what should be done is
  that the C99 math functions which are not provided by newlib should
  be supplied as weak aliases.  That way if GCC is not converting
  their invocations into the built-in versions the tests will not fail
  with link errors.

  I am attaching a patch that would implement this idea.  What do
  people think ?  Should this patch be checked in ?

Cheers
  Nick

gcc/testsuite/ChangeLog
2004-12-02  Nick Clifton  <nickc@redhat.com>

	* gcc.dg/builtins-config.h: Remove test for _NEWLIB_VERSION as
	<limits.h> is now picked up from the gcc/include directory and
	not the newlib/libc/include directory.
        * gcc.dg/builtins-18.c: Provide weak aliases of functions not
	provided by newlib.
        * gcc.dg/builtins-20.c: Likewise.

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