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

[Nick Clifton <nickc at redhat dot com>]

Hi Roger,

> > 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.
>
>
> My personal feeling is that this isn't the right way to do this.  The
> purpose of builtins-config.h is to correctly set HAVE_C99_RUNTIME for
> precisely those targets that have it.  Your change, rather than fixing
> or correcting this definition for newlib targets, circumvents the tests
> themselves by providing implementations of functions that HAVE_C99_RUNTIME
> asserts we should already have.   Seems backward.
>
> The source of the problem is that #include <limits.h> is no longer
> guaranteed to define _NEWLIB_VERSION on newlib targets as we may now
> get the compiler's limits.h instead.  As an alternative, might I suggest
> that a suitable fix would be to include <sys/types.h> instead?  In fact,
> any of newlib's headers that include <_ansi.h> and thereby <newlib.h>
> would do.  The file <sys/types.h> is a reasonable candidate as it should
> be portable, and shouldn't define any fancy macros like string.h, math.h,
> stdio.h or stdlib.h that could interfere with the builtins tests
> themselves.
>
> Does this sound reasonable?  Could you check that it resolves the
> testsuite failures you are seeing?

It certainly does.  I had found that #include <stdio.h> works just fine 
as a replacement for #include <limits.h>.  My only worry about this 
(much simpler) change is that in theory any system header file could be 
subject to fixincludes processing, so relying on <stdio.h> is, 
theoretically, just as bad as relying upon <limits.h>.

If however the list feels that this is the way to go then I will happily 
submit a revised patch.

Cheers
  Nick