Fwd: [RFA] Fix libstdc++ configure failure on cross-builds

[Paul Koning]

Begin forwarded message:

> From: Paul Koning <paul_koning@dell.com>
> Date: December 3, 2010 12:05:10 PM EST
> To: "Joseph S. Myers" <joseph@codesourcery.com>
> Cc: gcc-patches <gcc-patches@gcc.gnu.org>
> Subject: Re: [RFA] Fix libstdc++ configure failure on cross-builds
> 
> 
> On Dec 3, 2010, at 11:56 AM, Joseph S. Myers wrote:
> 
>> On Fri, 3 Dec 2010, Paul Koning wrote:
>> 
>>> Index: gcc-4.5.1/libtool.m4
>>> ===================================================================
>>> --- gcc-4.5.1/libtool.m4	(revision 147400)
>>> +++ gcc-4.5.1/libtool.m4	(working copy)
>>> @@ -1715,6 +1715,11 @@
>>>    lt_cv_dlopen_self=yes
>>>    ;;
>>> 
>>> +  netbsd*)
>>> +    lt_cv_dlopen="dlopen"
>>> +    lt_cv_dlopen_libs=
>>> +    ;;
>>> +
>> 
>> libtool patches need to go to upstream libtool first.  Is this a backport 
>> from upstream?
> 
> No, it's a pilot error, supplying the wrong patch.
> 
>> 
>>> @@ -230,7 +230,8 @@
>>>      glibcxx_have_gc_sections=yes
>>>    fi
>>>  fi
>>> -  if test "$glibcxx_have_gc_sections" = "yes"; then
>>> +  if test "$glibcxx_have_gc_sections" = "yes" &&
>>> +	test x$gcc_no_link != xyes; then
>> 
>> Please explain why this is needed for your target when it isn't needed 
>> by other people building for bare-metal targets that cannot link at this 
>> point.
>> 
>> (In any case, I think NetBSD, like GNU/Linux, *should* be a target where 
>> building libstdc++ requires the ability to run link tests.  That is, you 
>> should need to build libc in your sysroot with a C-only compiler before 
>> building one supporting C++, and all the AC_DEFINE settings in 
>> crossconfig.m4 for particular functions should be replaced with calls to 
>> the appropriate configure test macros.)
> 
> I need to dig deeper.  I thought I understood well enough what's going on, but you're raising questions that go beyond my understanding of cross-builds.  
> 
> So cancel the request for now, if I still have something to propose later I will reopen the question.
> 
> Thanks for the feedback.
> 
> 	paul
>