[gtk/theme-fallback-fix] themes: Make fallback work a bit better

[Matthias Clasen <matthiasc src gnome org>]

commit 9f6b3e179f4d568cf8fbde0732db27431bc111bd
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Apr 15 17:08:15 2021 -0400

    themes: Make fallback work a bit better
    
    One case we did not include in fd329e0ec582d7562f444b is
    
    Adwaita-dark -> Default:dark
    
    It turns out that it is needed.

 gtk/gtkcssprovider.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkcssprovider.c b/gtk/gtkcssprovider.c
index 56b243f1c1..91e5f6240f 100644
--- a/gtk/gtkcssprovider.c
+++ b/gtk/gtkcssprovider.c
@@ -1384,7 +1384,12 @@ gtk_css_provider_load_named (GtkCssProvider *provider,
     }
   else
     {
-      /* Things failed! Fall back! Fall back! */
+      /* Things failed! Fall back! Fall back!
+       *
+       * We accept the names HighContrast, HighContrastInverse,
+       * Adwaita and Adwaita-dark as aliases for the variants
+       * of the Default theme.
+       */
       if (strcmp (name, "HighContrast") == 0)
         {
           if (g_strcmp0 (variant, "dark") == 0)
@@ -1394,6 +1399,8 @@ gtk_css_provider_load_named (GtkCssProvider *provider,
         }
       else if (strcmp (name, "HighConstrastInverse") == 0)
         gtk_css_provider_load_named (provider, DEFAULT_THEME_NAME, "hc-dark");
+      else if (strcmp (name, "Adwaita-dark") == 0)
+        gtk_css_provider_load_named (provider, DEFAULT_THEME_NAME, "dark");
       else if (strcmp (name, DEFAULT_THEME_NAME) != 0)
         gtk_css_provider_load_named (provider, DEFAULT_THEME_NAME, variant);
       else