[nautilus/wip/corey/dnd_features] dnd: Allow GDK_ACTION_COPY within the same folder

[Corey Berla <coreyberla src gnome org>]

commit fcc8007df492eef883047eec2ffc2a8c300a57fd
Author: Corey Berla <corey berla me>
Date:   Thu Aug 18 12:11:11 2022 -0700

    dnd: Allow GDK_ACTION_COPY within the same folder
    
    We are setting the preferred action to 0 when the source and dest are
    in the same folder.  This prevents the ability to hold CTRL and perform
    a copy operation (which worked in 42).  It isn't clear why you can't
    override a 0 preferred action with key modifiers.
    
    In order to keep consistency, remove this check in
    nautilus_dnd_get_preferred_action() and add it to
    nautilus_files_view_drop_proxy_received_uris() (only if the action
    is MOVE).
    
    Fixes: https://gitlab.gnome.org/GNOME/nautilus/-/issues/2438

 src/nautilus-dnd.c            |  3 +--
 src/nautilus-files-view-dnd.c | 10 ++++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)
---
diff --git a/src/nautilus-dnd.c b/src/nautilus-dnd.c
index 7e537517c..08330da57 100644
--- a/src/nautilus-dnd.c
+++ b/src/nautilus-dnd.c
@@ -204,8 +204,7 @@ nautilus_dnd_get_preferred_action (NautilusFile *target_file,
         }
 
         target_location = nautilus_file_get_location (target_file);
-        if (g_file_equal (target_location, dropped) ||
-            g_file_has_parent (dropped, target_location))
+        if (g_file_equal (target_location, dropped))
         {
             return 0;
         }
diff --git a/src/nautilus-files-view-dnd.c b/src/nautilus-files-view-dnd.c
index 69254be65..c75ccb133 100644
--- a/src/nautilus-files-view-dnd.c
+++ b/src/nautilus-files-view-dnd.c
@@ -350,12 +350,22 @@ nautilus_files_view_drop_proxy_received_uris (NautilusFilesView *view,
                                               GdkDragAction      action)
 {
     g_autofree char *container_uri = NULL;
+    g_autoptr (GFile) source_location = g_file_new_for_uri (source_uri_list->data);
+    g_autoptr (GFile) target_location = g_file_new_for_uri (target_uri);
 
     if (target_uri == NULL)
     {
         container_uri = nautilus_files_view_get_backing_uri (view);
         g_assert (container_uri != NULL);
     }
+    if (g_file_has_parent (source_location, target_location) &&
+        action & GDK_ACTION_MOVE)
+    {
+        /* By default dragging to the same directory is allowed so that
+         * users can duplicate a file using the CTRL modifier key.  Prevent
+         * an accidental MOVE, by rejecting what would be an error anyways. */
+        return;
+    }
 
     if (action == GDK_ACTION_ASK)
     {