[gtk/wip/Jehan/fix-macos-pkg-config] meson, configure, gtk: fix GDK pkg-config for macOS.

[Jehan <jehanp src gnome org>]

commit 72585ace4376ab2571509eb13527f6feacfe83c7
Author: Jehan <jehan girinstud io>
Date:   Thu Dec 30 12:38:28 2021 +0100

    meson, configure, gtk: fix GDK pkg-config for macOS.
    
    Since commit 7e732caa1e, gdkquartz.h is included directly from
    gdkquartz-cocoa-access.h, yet it is in the include/gtk+-3.0/gdk
    subdirectory (which is currently not in the dir list to search for
    headers). It is made so on purpose so that the headers is also found in
    the source tree. Yet it also definitely needs to be found in the install
    prefix tree, which is the job of the pkg-config file.

 configure.ac |  2 ++
 meson.build  | 13 ++++++++-----
 2 files changed, 10 insertions(+), 5 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index f99621d568..c49f97db03 100644
--- a/configure.ac
+++ b/configure.ac
@@ -410,6 +410,8 @@ if test "x$enable_quartz_backend" = xyes; then
   GDK_WINDOWING="$GDK_WINDOWING
 #define GDK_WINDOWING_QUARTZ"
   GDK_EXTRA_LIBS="$GDK_EXTRA_LIBS -Wl,-framework,Cocoa"
+  # See discussion of MR !535.
+  GDK_EXTRA_CFLAGS="$GDK_EXTRA_CFLAGS -I${includedir}/gtk-$GTK_API_VERSION/gdk/"
   DISABLE_ON_QUARTZ='%'
   AM_CONDITIONAL(USE_QUARTZ, true)
   if test "x$quartz_relocation" = xyes; then
diff --git a/meson.build b/meson.build
index 15cca3de15..8ea5708a8d 100644
--- a/meson.build
+++ b/meson.build
@@ -499,9 +499,10 @@ else
   cdata.set_quoted('ISO_CODES_PREFIX', get_option('prefix'))
 endif
 
-backend_immodules = []
+backend_immodules   = []
 
-pc_gdk_extra_libs = []
+pc_gdk_extra_libs   = []
+pc_gdk_extra_cflags = []
 
 cairo_found_type = cairo_dep.type_name()
 if cairo_found_type == 'internal'
@@ -665,8 +666,10 @@ if broadway_enabled
 endif
 
 if quartz_enabled
-  pc_gdk_extra_libs += ['-Wl,-framework,Cocoa', '-Wl,-framework,Carbon', '-Wl,-framework,CoreGraphics']
-  backend_immodules += ['quartz']
+  pc_gdk_extra_libs   += ['-Wl,-framework,Cocoa', '-Wl,-framework,Carbon', '-Wl,-framework,CoreGraphics']
+  # See discussion of MR !535.
+  pc_gdk_extra_cflags += ['-I${includedir}/gtk-@0@/gdk/'.format(gtk_api_version)]
+  backend_immodules   += ['quartz']
 endif
 
 extra_demo_ldflags = []
@@ -950,7 +953,7 @@ pkgconf.set('GDK_EXTRA_LIBS', ' '.join(pc_gdk_extra_libs))
 pkgconf.set('GSK_EXTRA_LIBS', '')
 pkgconf.set('GTK_EXTRA_LIBS', '')
 
-pkgconf.set('GDK_EXTRA_CFLAGS', '')
+pkgconf.set('GDK_EXTRA_CFLAGS', ' '.join(pc_gdk_extra_cflags))
 pkgconf.set('GSK_EXTRA_CFLAGS', '')
 pkgconf.set('GTK_EXTRA_CFLAGS', '')