[epiphany/wip/smcv/libportal-optional] build: Allow libportal support to be disabled

[Simon McVittie <smcv src gnome org>]

commit afd155430075cee5380334a9c263cc28426fc79c
Author: Simon McVittie <smcv debian org>
Date:   Thu Oct 1 10:07:28 2020 +0100

    build: Allow libportal support to be disabled
    
    It isn't clear whether the API/ABI of libportal are entirely stable yet
    (https://github.com/flatpak/libportal/issues/33) so it is not necessarily
    appropriate for longer-term-supported OS distributions to include it.
    When building a version of epiphany for a distribution package, which is
    only intended to be packaged in a format other than as a Flatpak app,
    libportal isn't necessary anyway.
    
    libportal is also Linux-specific, so non-Linux OSs will likely want to
    disable it (even if it might compile successfully).
    
    Signed-off-by: Simon McVittie <smcv debian org>

 lib/ephy-flatpak-utils.c |  9 +++++++++
 meson.build              | 26 ++++++++++++++------------
 meson_options.txt        |  6 ++++++
 3 files changed, 29 insertions(+), 12 deletions(-)
---
diff --git a/lib/ephy-flatpak-utils.c b/lib/ephy-flatpak-utils.c
index 6f91e5ff5..818af95f4 100644
--- a/lib/ephy-flatpak-utils.c
+++ b/lib/ephy-flatpak-utils.c
@@ -28,7 +28,9 @@
 #include <fcntl.h>
 #include <gio/gio.h>
 #include <gio/gunixfdlist.h>
+#if USE_LIBPORTAL
 #include <libportal/portal-gtk3.h>
+#endif
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -63,6 +65,7 @@ ephy_is_running_inside_flatpak (void)
   return under_flatpak;
 }
 
+#if USE_LIBPORTAL
 static void
 opened_uri (GObject      *object,
             GAsyncResult *result,
@@ -81,11 +84,13 @@ opened_uri (GObject      *object,
   if (!res)
     g_warning ("%s", error->message);
 }
+#endif
 
 static void
 ephy_open_uri (const char *uri,
                gboolean    is_dir)
 {
+#if USE_LIBPORTAL
   GApplication *application;
   GtkWindow *window;
   XdpParent *parent;
@@ -101,6 +106,10 @@ ephy_open_uri (const char *uri,
     xdp_portal_open_uri (g_steal_pointer (&portal), parent, uri, XDP_OPEN_URI_FLAG_ASK, NULL, opened_uri, 
GINT_TO_POINTER (FALSE));
 
   xdp_parent_free (parent);
+#else
+  g_warning ("Flatpak portal support disabled at compile time, cannot open %s",
+             uri);
+#endif
 }
 
 void
diff --git a/meson.build b/meson.build
index 9160738bd..4dcd7ad5b 100644
--- a/meson.build
+++ b/meson.build
@@ -1,7 +1,7 @@
 project('epiphany', 'c',
   license: 'GPL3+',
   version: '40.alpha',
-  meson_version: '>= 0.46.0',
+  meson_version: '>= 0.47.0',
   default_options: ['c_std=gnu11',
                     'warning_level=2']
 )
@@ -74,16 +74,6 @@ if gsb_api_key != ''
 endif
 conf.set10('ENABLE_GSB', get_option('enable_gsb'))
 
-config_h = declare_dependency(
-  sources: vcs_tag(
-    input: configure_file(
-      output: 'config.h.in',
-      configuration: conf
-    ),
-    output: 'config.h'
-  )
-)
-
 glib_requirement = '>= 2.61.2'
 gtk_requirement = '>= 3.24.0'
 nettle_requirement = '>= 3.4'
@@ -108,11 +98,23 @@ libsecret_dep = dependency('libsecret-1', version: '>= 0.19.0')
 libsoup_dep = dependency('libsoup-2.4', version: '>= 2.48.0')
 libxml_dep = dependency('libxml-2.0', version: '>= 2.6.12')
 nettle_dep = dependency('nettle', version: nettle_requirement)
-portal_dep = dependency('libportal', version: '>= 0.0.2')
+portal_dep = dependency('libportal', version: '>= 0.0.2', required: get_option('libportal'))
 sqlite3_dep = dependency('sqlite3', version: '>= 3.22')
 webkit2gtk_dep = dependency('webkit2gtk-4.0', version: webkitgtk_requirement)
 webkit2gtk_web_extension_dep = dependency('webkit2gtk-web-extension-4.0', version: webkitgtk_requirement)
 
+conf.set10('USE_LIBPORTAL', portal_dep.found())
+
+config_h = declare_dependency(
+  sources: vcs_tag(
+    input: configure_file(
+      output: 'config.h.in',
+      configuration: conf
+    ),
+    output: 'config.h'
+  )
+)
+
 cc = meson.get_compiler('c')
 gmp_dep = cc.find_library('gmp')
 m_dep = cc.find_library('m', required: false)
diff --git a/meson_options.txt b/meson_options.txt
index 7f3648781..cd83fcdca 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -4,6 +4,12 @@ option('developer_mode',
   description: 'Enable developer mode'
 )
 
+option('libportal',
+  type: 'feature',
+  value: 'enabled',
+  description: 'Depend on libportal for Flatpak support'
+)
+
 option('network_tests',
   type: 'feature',
   value: 'disabled',