SERVER-24508 DocumentComparator and ValueComparator

 - Changes the Document/Value library to require comparisons
   to be made in the context of a comparator object. This is
   prep work for full collation support in the aggregation
   system.
 - Adds injectExpressionContext() to propagate the
   ExpressionContext containing the comparator object to all
   DocumentSource, Accumulator, and Expression instances
   involved in the Pipeline.

1 files changed, 7 insertions, 5 deletions

diff --git a/src/mongo/db/pipeline/document_source_unwind.cpp b/src/mongo/db/pipeline/document_source_unwind.cpp
index b02723c1c94..82bb8f3adbe 100644
--- a/src/mongo/db/pipeline/document_source_unwind.cpp
+++ b/src/mongo/db/pipeline/document_source_unwind.cpp
@@ -174,11 +174,13 @@ intrusive_ptr<DocumentSourceUnwind> DocumentSourceUnwind::create(
     const string& unwindPath,
     bool preserveNullAndEmptyArrays,
     const boost::optional<string>& indexPath) {
-    return new DocumentSourceUnwind(expCtx,
-                                    FieldPath(unwindPath),
-                                    preserveNullAndEmptyArrays,
-                                    indexPath ? FieldPath(*indexPath)
-                                              : boost::optional<FieldPath>());
+    intrusive_ptr<DocumentSourceUnwind> source(
+        new DocumentSourceUnwind(expCtx,
+                                 FieldPath(unwindPath),
+                                 preserveNullAndEmptyArrays,
+                                 indexPath ? FieldPath(*indexPath) : boost::optional<FieldPath>()));
+    source->injectExpressionContext(expCtx);
+    return source;
 }
 
 boost::optional<Document> DocumentSourceUnwind::getNext() {