GODRIVER-3205 Use bson options when decoding distinct results

internal/integration/collection_test.go

@@ -899,6 +899,24 @@ func TestCollection(t *testing.T) {
 				assert.EqualValues(mt, tc.want, got, "expected result %v, got %v", tc.want, got)
 			})
 		}
+
+		collOpts := options.Collection().SetBSONOptions(&options.BSONOptions{AllowTruncatingDoubles: true})
+		opts := mtest.NewOptions().CollectionOptions(collOpts)
+
+		mt.RunOpts("distinct with bson options", opts, func(mt *mtest.T) {
+			_, err := mt.Coll.InsertOne(context.Background(), bson.D{{"y", 1.7}})
+			assert.NoError(mt, err, "failed to insert double")
+
+			filter := bson.D{{"y", bson.D{{"$gt", 1}}}}
+
+			res := mt.Coll.Distinct(context.Background(), "y", filter)
+			assert.Nil(mt, res.Err(), "Distinct error: %v", res.Err())
+
+			var got []int32
+			assert.NoError(t, res.Decode(&got))
+
+			assert.EqualValues(mt, []int32{1}, got)
+		})
 	})
 	mt.RunOpts("find", noClientOpts, func(mt *mtest.T) {
 		mt.Run("found", func(mt *mtest.T) {

mongo/collection.go

@@ -86,6 +86,9 @@ func mergeCollectionOptions(opts ...*options.CollectionOptions) *options.Collect
 		if opt.Registry != nil {
 			c.Registry = opt.Registry
 		}
+		if opt.BSONOptions != nil {
+			c.BSONOptions = opt.BSONOptions
+		}
 	}
 
 	return c
@@ -1304,7 +1307,6 @@ func (coll *Collection) Distinct(
 	filter interface{},
 	opts ...*options.DistinctOptions,
 ) *DistinctResult {
-
 	if ctx == nil {
 		ctx = context.Background()
 	}
@@ -1384,8 +1386,9 @@ func (coll *Collection) Distinct(
 	}
 
 	return &DistinctResult{
-		reg: coll.registry,
-		arr: bson.RawArray(arr),
+		reg:      coll.registry,
+		arr:      bson.RawArray(arr),
+		bsonOpts: coll.bsonOpts,
 	}
 }
 

mongo/results.go

@@ -8,6 +8,8 @@ package mongo
 
 import (
 	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo/options"
+	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
 	"go.mongodb.org/mongo-driver/x/mongo/driver/operation"
 )
 
@@ -179,9 +181,10 @@ type CollectionSpecification struct {
 // that error. If the operation did not return any data, all DistinctResult
 // methods will return ErrNoDocuments.
 type DistinctResult struct {
-	err error
-	arr bson.RawArray
-	reg *bson.Registry
+	err      error
+	arr      bson.RawArray
+	reg      *bson.Registry
+	bsonOpts *options.BSONOptions
 }
 
 // Decode will unmarshal the array represented by this DistinctResult into v. If
@@ -193,12 +196,15 @@ type DistinctResult struct {
 // errors from the unmarshalling process without any modification. If v is nil
 // or is a typed nil, an error will be returned.
 func (dr *DistinctResult) Decode(v any) error {
-	val := bson.RawValue{
-		Value: dr.arr,
-		Type:  bson.TypeArray,
-	}
+	doc := bsoncore.NewDocumentBuilder().
+		AppendValue("arr", bsoncore.Value{
+			Type: bsoncore.TypeArray,
+			Data: dr.arr,
+		}).Build()
+
+	dec := getDecoder(doc, dr.bsonOpts, dr.reg)
 
-	return val.UnmarshalWithRegistry(dr.reg, v)
+	return dec.Decode(&struct{ Arr any }{Arr: v})
 }
 
 // Err provides a way to check for query errors without calling Decode. Err