Temporal.Duration.prototype.round: Condition to convert zonedRelativeTo to plainRelativeTo incorrect

[anba]

Step 29:

If zonedRelativeTo is not undefined; and smallestUnit is any of "year", "month", "week"; and any of duration.[[Years]], duration.[[Months]], duration.[[Weeks]], duration.[[Days]] ≠ 0; then

There are two issues:

• The condition should be "or" instead of "and".
• largestUnit needs to be tested, too.

This condition should instead be:

1. If zonedRelativeTo is not undefined, then
  1. If smallestUnit is any of "year", "month", "week"; or largestUnit is any of "year", "month", "week"; or any of duration.[[Years]], duration.[[Months]], duration.[[Weeks]], duration.[[Days]] ≠ 0; then
    1. Set plainRelativeTo to ? ToTemporalDate(zonedRelativeTo).

• largestUnit is tested for BalanceDateDurationRelative.
• smallestUnit is tested for RoundDuration.
• The duration units are tested for UnbalanceDateDurationRelative.

[anba]

Is the check for duration.[[Days]] ≠ 0 actually needed? Because days in UnbalanceDateDurationRelative can be any value (when years, months, and weeks are all zero).

[ptomato]

Agreed, thanks for catching this. Also agreed that the duration.[[Days]] check is not needed.

[ptomato]

The and/or issue is already fixed in #2671. I'll push a fix for the largestUnit issue there, too. Note that the conditions change as a result of the commit "Normative: Precalculate PlainDateTime from ZonedDateTime in more places", so the duration.[[Days]] check will actually be needed.