meson: Make missing declarations an error

Detects missing includes and missing static defitions

meson.build

@@ -39,6 +39,7 @@ test_c_args = [
   '-Wcast-align',
   '-Wdeclaration-after-statement',
   ['-Werror=format-security', '-Werror=format=2'],
+  '-Werror=missing-declarations',
   '-Wformat-nonliteral',
   '-Wformat-security',
   '-Wmaybe-uninitialized',

src/auth.c

@@ -63,7 +63,7 @@ pam_conversation_cb(int num_msg, const struct pam_message **msg,
 
 
 /* return TRUE if pin is correct, FALSE otherwise */
-gboolean
+static gboolean
 authenticate (PhoshAuth *self, const gchar* number)
 {
   PhoshAuthPrivate *priv = phosh_auth_get_instance_private (self);

src/lockscreen.c

@@ -128,7 +128,7 @@ show_unlock_page (PhoshLockscreen *self)
 
 
 /* callback of async auth task */
-void
+static void
 auth_async_cb (PhoshAuth *auth, GAsyncResult *result, PhoshLockscreen *self)
 {
   PhoshLockscreenPrivate *priv;

src/phosh.c

@@ -646,7 +646,7 @@ phosh_shell_get_default (void)
 }
 
 
-gboolean
+static gboolean
 sigterm_cb (gpointer unused)
 {
   g_debug ("Cleaning up");

src/settings.c

@@ -44,12 +44,6 @@ typedef struct _PhoshSettings
 G_DEFINE_TYPE_WITH_PRIVATE (PhoshSettings, phosh_settings, GTK_TYPE_WINDOW)
 
 
-GtkWidget *phosh_settings (const char* name)
-{
-  return g_object_new (PHOSH_TYPE_SETTINGS, "name", name, NULL);
-}
-
-
 static void
 brightness_value_changed_cb (GtkScale *scale_brightness, gpointer *unused)
 {

src/settings/brightness.c

@@ -10,11 +10,14 @@
 #include <gio/gio.h>
 #include <gtk/gtk.h>
 
+#include "settings/brightness.h"
+
+
 GDBusProxy *brightness_proxy;
 gboolean setting_brightness;
 
 
-void
+static void
 brightness_changed_cb (GDBusProxy *proxy,
                        GVariant *changed_props,
                        GVariant *invalidated_props,
@@ -85,7 +88,7 @@ brightness_init (GtkScale *scale)
 
 
 
-void
+static void
 brightness_set_cb (GDBusProxy *proxy, GAsyncResult *res, gpointer unused)
 {
   GError *err = NULL;

src/wwan/phosh-wwan-mm.c

@@ -104,7 +104,7 @@ phosh_wwan_mm_update_signal_quality (PhoshWWanMM *self)
 }
 
 
-const char *
+static const char *
 user_friendly_access_tec (guint access_tec)
 {
   switch (access_tec) {

tests/phoshstub.c

 /* Stubs so we don't need to run the shell */
 
 #include <glib.h>
+#include "phosh-wayland.h"
+#include "phosh.h"
 
 gpointer
 phosh_shell_get_default (void)