The trait SupportsOnConflictClauseWhere is not implemented for sqlite::backend::SqliteOnConflictClause

[LucaCappelletti94]

Hi,

It seems that the SQLite backend does not support theWHERE clause when executing an upsert operation, such as:

diesel::insert_into(users::table)
.values(self)
.on_conflict(users::id)
.do_update()
.set(self)
.filter(...) // <- without the filter statement this compiles.
.get_results(conn)

But to my understanding, WHERE clauses are supported in SQLite's upsert.

Is there some reason for SupportsOnConflictClauseWhere not being currently implemented for SqliteOnConflictClause or is it just something to add on the TODO list? If it is the latter, I would be happy to try and contribute it.

Thank you and have a great weekend,
Luca