[gnome-software/gnome-40: 1/2] gs-details-page: Enhance the alternates deduplication cycle

[Milan Crha <mcrha src gnome org>]

commit 2683bbe1df8419cb74bc415412782c968d0ad760
Author: Milan Crha <mcrha redhat com>
Date:   Wed May 5 16:10:21 2021 +0200

    gs-details-page: Enhance the alternates deduplication cycle
    
    The deduplication works as long as the array doesn't contain the same pointers
    or when those are not interleaved. Being interleaved it can happen the first
    occurrence of the second or later instance is skipped due to the array content
    shift with g_ptr_array_remove(), which removed the first occurrence of the data.
    
    Closes https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1192

 src/gs-details-page.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/src/gs-details-page.c b/src/gs-details-page.c
index c985f3b06..aa05a7571 100644
--- a/src/gs-details-page.c
+++ b/src/gs-details-page.c
@@ -792,6 +792,9 @@ app_origin_equal (GsApp *a,
        g_autofree gchar *a_origin_ui = NULL, *b_origin_ui = NULL;
        GFile *a_local_file, *b_local_file;
 
+       if (a == b)
+               return TRUE;
+
        a_origin_ui = gs_app_get_origin_ui (a);
        b_origin_ui = gs_app_get_origin_ui (b);
 
@@ -872,16 +875,25 @@ gs_details_page_get_alternates_cb (GObject *source_object,
         * items long. */
        for (guint i = 0; i < gs_app_list_length (list); i++) {
                GsApp *i_app = gs_app_list_index (list, i);
+               gboolean did_remove = FALSE;
 
                for (guint j = i + 1; j < gs_app_list_length (list);) {
                        GsApp *j_app = gs_app_list_index (list, j);
 
                        if (app_origin_equal (i_app, j_app)) {
                                gs_app_list_remove (list, j_app);
+                               did_remove = TRUE;
                        } else {
                                j++;
                        }
                }
+
+               /* Needed to catch cases when the same pointer is in the array multiple times,
+                  interleaving with another pointer. The removal can skip the first occurrence
+                  due to the g_ptr_array_remove() removing the first instance in the array,
+                  which shifts the array content. */
+               if (did_remove)
+                       i--;
        }
 
        /* add the local file to the list so that we can carry it over when