[devhelp] parser: print warning if index file format version 1 still used

[Sébastien Wilmet <swilmet src gnome org>]

commit a09e1abd5d9adf62d62634b4bd728745e5548175
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Dec 22 16:13:27 2017 +0100

    parser: print warning if index file format version 1 still used
    
    Now the format version 1 is officially deprecated. The plan is to remove
    its support in the future, if it gets in the way. For example if one day
    the version 3 is created, then the support for version 1 can definitely
    be removed, supporting two versions in parallel is enough.
    
    With the API docs installed on my system, only the libxml2 still uses
    the format version 1.

 src/dh-parser.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/src/dh-parser.c b/src/dh-parser.c
index a35457a..65ecb2a 100644
--- a/src/dh-parser.c
+++ b/src/dh-parser.c
@@ -569,6 +569,13 @@ dh_parser_read_file (GFile   *index_file,
                 gz = TRUE;
         }
 
+        if (parser->version == FORMAT_VERSION_1)
+                g_warning ("The file '%s' uses the Devhelp index file format version 1, "
+                           "which is deprecated. A future version of Devhelp may remove "
+                           "the support for the format version 1. The index file should "
+                           "be ported to the Devhelp index file format version 2.",
+                           index_file_uri);
+
         parser->markup_parser = g_new0 (GMarkupParser, 1);
         parser->markup_parser->start_element = parser_start_node_cb;
         parser->markup_parser->end_element = parser_end_node_cb;