[gtk+] demo: Link against Harfbuzz

[Emmanuele Bassi <ebassi src gnome org>]

commit c8686f0c474ad96075938367ae9065105ed1e03f
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Tue Jan 26 11:46:48 2016 +0000

    demo: Link against Harfbuzz
    
    The font features demo started calling the Harfbuzz API directly
    starting from commit 9de3b24c205f1c647292a490f92f21a776b931a4. Harfbuzz
    is an implicit dependency of Pango on some platforms, but it's not part
    of the public dependencies; this means that we cannot expect to link to
    Pango and automatically get Harfbuzz symbols to link against —
    especially when things like --as-needed are in play.
    
    This change triggered build failures on non-Unix platforms, fixed by
    commit 2a9967731a3b77b102ada633c39b5a35efc80957, as well as build
    failures in Continuous, with this error message:
    
    /usr/lib/gcc/x86_64-gnomeostree-linux/4.9.3/../../../../x86_64-gnomeostree-linux/bin/ld:
    font_features.o: undefined reference to symbol 'hb_tag_to_string'
    //lib/libharfbuzz.so.0: error adding symbols: DSO missing from command
    line
    collect2: error: ld returned 1 exit status
    
    In order to get the font features demo to build everywhere we should
    take an explicit, though optional, check on Harfbuzz, and conditionally
    build the font features demo with the right compiler and linker flags.

 configure.ac               |    9 +++++++++
 demos/gtk-demo/Makefile.am |   17 ++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index c15aaa9..3ff4615 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1691,6 +1691,15 @@ fi
 AM_CONDITIONAL(HAVE_COLORD, test "x$have_colord" = "xyes")
 
 ##################################################
+# Check for harfbuzz
+##################################################
+
+PKG_CHECK_MODULES(HARFBUZZ, harfbuzz >= 0.9, have_harfbuzz=yes, have_harfbuzz=no)
+AC_SUBST(HARFBUZZ_CFLAGS)
+AC_SUBST(HARFBUZZ_LIBS)
+AM_CONDITIONAL(BUILD_FONT_DEMO, [ test "x$have_harfbuzz" = xyes ])
+
+##################################################
 # Checks for gtk-doc and docbook-tools
 ##################################################
 
diff --git a/demos/gtk-demo/Makefile.am b/demos/gtk-demo/Makefile.am
index 64cc8c4..60e4e13 100644
--- a/demos/gtk-demo/Makefile.am
+++ b/demos/gtk-demo/Makefile.am
@@ -70,12 +70,18 @@ demos_base =                                        \
        transparent.c                           \
        tree_store.c
 
+demos_opt =
+
+if BUILD_FONT_DEMO
+demos_opt += font_features.c
+endif
+
 if OS_UNIX
-demos = $(demos_base) font_features.c pagesetup.c
-else
-demos = $(demos_base)
+demos_opt += pagesetup.c
 endif
 
+demos = $(demos_base) $(demos_opt)
+
 AM_CPPFLAGS = \
        -I$(top_srcdir)                         \
        -I$(top_builddir)/gdk                   \
@@ -94,6 +100,11 @@ LDADDS = \
        $(GDK_DEP_LIBS)                         \
        -lm
 
+if BUILD_FONT_DEMO
+AM_CPPFLAGS += $(HARFBUZZ_CFLAGS)
+LDADDS += $(HARFBUZZ_LIBS)
+endif
+
 bin_PROGRAMS = gtk3-demo gtk3-demo-application
 
 desktopdir = $(datadir)/applications