build: Fix C++ issues with automake

This is an attempt to fix the broken situation we've been in where
automake links libcairo.la with c++ because it might potentially maybe
include C++ files.

Those potential files only exist in Chris' throwaway backends (skia, qt)
and the BeOS backend, so for 99.99% of cases, these backends are not
needed and linking with c++ is overkill. Also, no one wants to have
libcairo.so link to libstdc++.

This patch fixes that in mutliple steps:
1) Add build infrastructure to distinguish between C and C++ backends.
   This is done by allowing to specify backend_sources as well as
   backend_cxx_sources variables in Makefile.sources.
2) Optionally build a libcairo_cxx.la noinst library
   This intermediate library is built for C++ backends only and therefor
   linked using c++. It is then linked into the final libcairo.la. This
   does not require c++, so the linking of libcairo.la is done with cc.

This also works around various weirdnesses that the current build system
exposes, where it assumes cisms when in fact using c++ semantics, like
not detecting c++ properly or:
https://bugzilla.redhat.com/show_bug.cgi?id=606523

1 files changed, 6 insertions, 1 deletions

diff --git a/build/configure.ac.features b/build/configure.ac.features
index 203d2bf3..d349a844 100644
--- a/build/configure.ac.features
+++ b/build/configure.ac.features
@@ -83,15 +83,16 @@ CAIRO_MAKEFILE_ACCUMULATE_FEATURE(*,*,no,!,
 dnl Collect list of source files for all public features
 CAIRO_MAKEFILE_ACCUMULATE(*,
 [dnl
-all_$1_files = $(all_$1_headers) $(all_$1_private) $(all_$1_sources)
 all_$1_headers = $($1_headers)
 all_$1_private = $($1_private)
+all_$1_cxx_sources = $($1_cxx_sources)
 all_$1_sources = $($1_sources)
 ])dnl
 CAIRO_MAKEFILE_ACCUMULATE_FEATURE(*,*,*,!,
 [dnl
 all_$1_headers += $($1_$2_headers)
 all_$1_private += $($1_$2_private)
+all_$1_cxx_sources += $($1_$2_cxx_sources)
 all_$1_sources += $($1_$2_sources)]dnl
 )dnl
 
@@ -100,12 +101,14 @@ CAIRO_MAKEFILE_ACCUMULATE(*,
 [dnl
 enabled_$1_headers = $($1_headers)
 enabled_$1_private = $($1_private)
+enabled_$1_cxx_sources = $($1_cxx_sources)
 enabled_$1_sources = $($1_sources)
 ])dnl
 CAIRO_MAKEFILE_ACCUMULATE_FEATURE(*,yes,*,!,
 [dnl
 enabled_$1_headers += $($1_$2_headers)
 enabled_$1_private += $($1_$2_private)
+enabled_$1_cxx_sources += $($1_$2_cxx_sources)
 enabled_$1_sources += $($1_$2_sources)]dnl
 )dnl
 
@@ -115,6 +118,7 @@ dnl Collect list of source files for all private features
 CAIRO_MAKEFILE_ACCUMULATE_FEATURE(*,*,*,,
 [dnl
 all_$1_private += $($1_$2_private) $($1_$2_headers)
+all_$1_cxx_sources += $($1_$2_cxx_sources)
 all_$1_sources += $($1_$2_sources)]dnl
 )dnl
 
@@ -122,6 +126,7 @@ dnl Collect list of source files for enabled private features
 CAIRO_MAKEFILE_ACCUMULATE_FEATURE(*,yes,*,,
 [dnl
 enabled_$1_private += $($1_$2_private) $($1_$2_headers)
+enabled_$1_cxx_sources += $($1_$2_cxx_sources)
 enabled_$1_sources += $($1_$2_sources)]dnl
 )dnl