[cairo] How to remove cairo's libstdc++ dependency?

[Behdad Esfahbod]

On 07/24/2009 12:24 AM, M Joonas Pihlaja wrote:
> Hi,
>
> Since including the Qt surface code into cairo master the autotools
> are convinced we need to be linked using a C++ compiler even if the Qt
> surface isn't enabled.  This adds a dependency to libstdc++ to
> libcairo which to me at least is an unwelcome one.  It looks like
> we've had this issue before as well with the BeOS backend, and in that
> case the (imho kludgy) solution was just to comment out the backend
> from the sources list.
>
> So I spent a while trying to understand why automake thinks we need a
> C++ compiler to link and got as far as becoming very confused about
> our build system.  It appears to first think we're okay not to use C++
> compiler to link and then in a second phase of automagic it backs up
> and decides we need one after all.  If anyone has any ideas on how to
> get around this issue beyond "go bug the automake people", please do
> tell. :)

I actually did bug automake people last year.  Here's the excerpt:

=============================================
On Tue, 2008-04-15 at 20:09 +0200, Ralf Wildenhues wrote:
 > Hi Behdad,

Hi Ralf,

Thanks for the quick response.

 > * Behdad Esfahbod wrote on Tue, Apr 15, 2008 at 07:39:19PM CEST:
 > > In short, all cairo source is C code, except for the BeOS backend that
 > > is C++.  So we have a block like this in our Makefile.am:
 >
 > > However, even if CAIRO_HAS_BEOS_SURFACE is false, the C++ linker is
 > > chosen to link cairo.  That we want to avoid.  Any hints?
 >
 > You have to help automake pick the right linker, its linker choosing
 > algorithm is blissfully unaware of conditionals.  You should be able to
 > set libcairo_la_LINK or cairo_LINK inside conditionals.  Look in a
 > Makefile.in how they are typically set (since this is an implementation
 > detail, beware: this changed between 1.9.6 and 1.10+).

I would have been happy doing that if it was as simple as:

libcairo_la_LINK = $(LINK)
and
libcairo_la_LINK = $(CXXLINK)

But as it happens now I can't do that, since libcairo_la_LDFLAGS and
libcairo_la_CFLAGS need to go in the middle of the LINK command.  It
prolly works if I append at the end, but don't want to change any flag
orders (yet).

 > If that Makefile.am otherwise has no other C++ code, and you are not
 > using cairo_LDFLAGS, you can just override
 >   CXXLINK = $(LINK)

I like this one.

 > I guess.

Doesn't seem to work though.  My libcairo_la_LINK is still a modified
version of the CXXLINK.

 > Hope that helps.

It did.  I fully understand the problem now.

 > Of course somebody writing a patch to lift this
 > limitation in Automake would help even more.  ;-)

=============================================

behdad

> Joonas