[gtk/wip/smcv/aboutdialog-licenses] aboutdialog: Update precondition checks for new licenses added in 3.24.20

[Simon McVittie <smcv src gnome org>]

commit 6d8fb83aa9e2e063f5a067e18339954913b945cf
Author: Simon McVittie <smcv debian org>
Date:   Mon May 11 18:12:08 2020 +0100

    aboutdialog: Update precondition checks for new licenses added in 3.24.20
    
    To avoid making this mistake again, add a static assertion that the
    enum is in sync with gtk_license_info, and use the length of
    gtk_license_info for the precondition check.
    
    Signed-off-by: Simon McVittie <smcv debian org>
    Resolves: #2734

 gtk/gtkaboutdialog.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkaboutdialog.c b/gtk/gtkaboutdialog.c
index 8bfbdac52e..77b783d973 100644
--- a/gtk/gtkaboutdialog.c
+++ b/gtk/gtkaboutdialog.c
@@ -130,6 +130,7 @@ static const LicenseInfo gtk_license_info [] = {
   { N_("Apache License, Version 2.0"), "https://opensource.org/licenses/Apache-2.0"; },
   { N_("Mozilla Public License 2.0"), "https://opensource.org/licenses/MPL-2.0"; }
 };
+G_STATIC_ASSERT (G_N_ELEMENTS (gtk_license_info) - 1 == GTK_LICENSE_MPL_2_0);
 
 typedef struct
 {
@@ -2467,7 +2468,7 @@ gtk_about_dialog_set_license_type (GtkAboutDialog *about,
 
   g_return_if_fail (GTK_IS_ABOUT_DIALOG (about));
   g_return_if_fail (license_type >= GTK_LICENSE_UNKNOWN &&
-                    license_type <= GTK_LICENSE_AGPL_3_0_ONLY);
+                    license_type < G_N_ELEMENTS (gtk_license_info));
 
   priv = about->priv;