qemu/tests/qapi-schema/reserved-member-u.json

# Potential C member name collision
# We reject use of 'u' as a member name, to allow it for internal use in
# putting union branch members in a separate namespace from QMP members.
# This is true even for non-unions, because it is possible to convert a
# struct to flat union while remaining backwards compatible in QMP.
# TODO - we could munge the member name to 'q_u' to avoid the collision
{ 'struct': 'Oops', 'data': { 'u': 'str' } }