> db.c.drop();
true
> db.c.insert({x: [{y: 1}, {y: 2}]});
WriteResult({ "nInserted" : 1 })

// Match with no dotted field path returns the correct result. The explain indicates that
// the $match stage swapped in front of the $addFields, and was absorbed into the
// $cursor stage after being correctly renamed to a match on "x".
> db.c.aggregate([{$addFields: {z: "$x"}}, {$match: {z: {y: 1}}}]);
{ "_id" : ObjectId("59ef5d62b49385b9971e2c09"), "x" : [ { "y" : 1 }, { "y" : 2 } ], "z" : [ { "y" : 1 }, { "y" : 2 } ] }
> db.c.explain().aggregate([{$addFields: {z: "$x"}}, {$match: {z: {y: 1}}}]);
{
	"stages" : [
		{
			"$cursor" : {
				"query" : {
					"x" : {
						"$eq" : {
							"y" : 1
						}
					}
				},
				"queryPlanner" : {
					"plannerVersion" : 1,
					"namespace" : "test.c",
					"indexFilterSet" : false,
					"parsedQuery" : {
						"x" : {
							"$eq" : {
								"y" : 1
							}
						}
					},
					"winningPlan" : {
						"stage" : "COLLSCAN",
						"filter" : {
							"x" : {
								"$eq" : {
									"y" : 1
								}
							}
						},
						"direction" : "forward"
					},
					"rejectedPlans" : [ ]
				}
			}
		},
		{
			"$addFields" : {
				"z" : "$x"
			}
		}
	],
	"ok" : 1
}

// When a similar match is expressed using the dotted path "z.y", the matching document
// is incorrectly omitted from the result set. The explain indicates that the rename to "x.y"
// was not applied correctly.
> db.c.explain().aggregate([{$addFields: {z: "$x"}}, {$match: {"z.y": 1}}]);
{
	"stages" : [
		{
			"$cursor" : {
				"query" : {
					"z.y" : {
						"$eq" : 1
					}
				},
				"queryPlanner" : {
					"plannerVersion" : 1,
					"namespace" : "test.c",
					"indexFilterSet" : false,
					"parsedQuery" : {
						"z.y" : {
							"$eq" : 1
						}
					},
					"winningPlan" : {
						"stage" : "COLLSCAN",
						"filter" : {
							"z.y" : {
								"$eq" : 1
							}
						},
						"direction" : "forward"
					},
					"rejectedPlans" : [ ]
				}
			}
		},
		{
			"$addFields" : {
				"z" : "$x"
			}
		}
	],
	"ok" : 1
}