Proposal to have sqlc generate string constants for constraints

[andrewmbenton]

I have some code that looks like:

obj, err = queries.SomeQuery()
if err != nil {
	var pgErr *pgconn.PgError
	if errors.As(err, &pgErr) && pgErr.ConstraintName == "some_unique_key" {
		// Let user know about constraint violation
		return
	}
	// Log query failure and return 500
	return
}

It would be nice if I had string constants for all of my constraint names to compare against, and I think sqlc should be capable of building that for me.