A value assigned to a variable is never used.

Defect 76551 (STATIC_C)
Checker UNUSED_VALUE (subcategory none)
File: /src/mongoc/mongoc-cluster.c
Function _mongoc_cluster_auth_node_x509
/src/mongoc/mongoc-cluster.c, line: 860
Overwriting previous write to "username" with value from "mongoc_uri_get_username(cluster->uri)".

       username = mongoc_uri_get_username (cluster->uri);

/src/mongoc/mongoc-cluster.c, line: 850
Assigning value from """" to "username" here, but that stored value is overwritten before it can be used.

       const char *username = "";