[tracker/wip/carlosg/graphs: 4/4] libtracker-data: Don't assert on NULL subject

[Carlos Garnacho <carlosg src gnome org>]

commit 3bbeffaaa99e39c33fea7b02b3daf5384ad41716
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Apr 29 19:00:23 2020 +0200

    libtracker-data: Don't assert on NULL subject
    
    Getting a NULL subject in TriplesSameSubject handling is possible
    in queries like:
    
      DELETE {
        ?b a rdfs:Resource
      } WHERE {
        OPTIONAL { ?a nie:isStoredAs ?b }
      }
    
    If ?b didn't happen to get resolved to anything. In those cases,
    the SPARQL update definition says:
    
      If any solution produces a triple containing an unbound variable
      or an illegal RDF construct, such as a literal in a subject or
      predicate position, then that triple is not included when processing
      the operation: INSERT will not instantiate new data in the output
      graph, and DELETE will not remove anything.
    
    So we shouldn't assert here, and we should let the operation be
    optimized away. The latter is already handled, so remove the asserts.

 src/libtracker-data/tracker-sparql.c | 2 --
 1 file changed, 2 deletions(-)
---
diff --git a/src/libtracker-data/tracker-sparql.c b/src/libtracker-data/tracker-sparql.c
index 5eea62dfb..b17b99f1b 100644
--- a/src/libtracker-data/tracker-sparql.c
+++ b/src/libtracker-data/tracker-sparql.c
@@ -5319,12 +5319,10 @@ translate_TriplesSameSubject (TrackerSparql  *sparql,
 
        if (rule == NAMED_RULE_VarOrTerm) {
                _call_rule (sparql, rule, error);
-               g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
                sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyListNotEmpty, error);
        } else if (rule == NAMED_RULE_TriplesNode) {
                _call_rule (sparql, rule, error);
-               g_assert (!tracker_token_is_empty (&sparql->current_state.subject));
                sparql->current_state.token = &sparql->current_state.object;
                _call_rule (sparql, NAMED_RULE_PropertyList, error);
        }