If an OR was used, merging filters between different expressions would
not work correctly. If one of the sides had a set of series ids with a
condition and the other side had no series ids associated with the
expression, all of the series from the side with a condition would have
the condition ignored. Instead of defaulting a non-existant series
filter to true, it should just be false and the evaluation of the one
side that does exist should take care of determining if the series id
should be included or not. The AND condition used false correctly so did
not have to be changed.
If a tag did not exist and `!=` or `!~` were used, it would return false
even though the neither a field or a tag equaled those values. This has
now been modified to correctly return the correct series ids and the
correct condition.
Also fixed a panic that would occur when a tag caused a field access to
become unnecessary. The filter using the field access still got created
and used even though it was unnecessary, resulting in an attempted
access to a non-initialized map.
Fixes#5152 and a bunch of other miscellaneous issues.
a35d9602cd