Normative: Validate unit-valued options after all options are read

[sffc]

See #3116

This preserves the original call to GetOption, but it always calls it with the full list of units, and I pull the subset-checking logic into a separate AO.

I have two commits: an editorial change to split the AO in two, and a small normative change to move the validation later down at the call sites.

@nekevss @Manishearth

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.85%. Comparing base (ed49b0b) to head (09a2390).
Report is 2 commits behind head on main.

Additional details and impacted files

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##             main    #3130   +/-   ##
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  Coverage   96.85%   96.85%           
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[sffc]

The code that changes behavior with this PR is something like:

obj = {
    get largestUnit() {
        console.log("get largestUnit");
        return "years";
    },
    get smallestUnit() {
        console.log("get smallestUnit");
        return "seconds";
    },
}

Temporal.PlainTime.from("00:00").round(obj)

Current behavior: console logs "get largestUnit" and then RangeError is thrown.

New behavior: console logs both "get largestUnit" and "get smallestUnit", and then RangeError is thrown.

Note: the RangeError is because PlainTime does not allow "years" as a largestUnit. There is no difference in behavior if get largestUnit() returns an invalid string such as "INVALID".

(as noted previously, there doesn't appear to be Test262 coverage for this)

[gibson042]

The intended changes as I understand them do seem both reasonable and narrow, but I think the algorithms steps fail to properly implement them.

[gibson042]

Suggested simplification:

Suggested change

	1. Let _allowedStrings_ be a new empty List.
	1. Append *"auto"* to _allowedStrings_.
	1. Let _allowedStrings_ be « *"auto"* ».

[gibson042]

I wonder if it makes sense to keep the allowedValues list at all.

Suggested change

	1. Let _allowedValues_ be a new empty List.
	1. For each row of <emu-xref href="#table-temporal-units"></emu-xref>, except the header row, in table order, do
	1. Let _unit_ be the value in the "Value" column of the row.
	1. If the "Category" column of the row is ~date~ and _unitGroup_ is ~date~ or ~datetime~, append _unit_ to _allowedValues_.
	1. Else if the "Category" column of the row is ~time~ and _unitGroup_ is ~time~ or ~datetime~, append _unit_ to _allowedValues_.
	1. If _extraValues_ is present, then
	1. Set _allowedValues_ to the list-concatenation of _allowedValues_ and _extraValues_.
	1. If _allowedValues_ does not contain _value_, throw a RangeError exception.
	1. If _extraValues_ is present and _extraValues_ contains _value_, return ~unused~.
	1. Let _category_ be the value in the “Category” column of the row of <emu-xref href="#table-temporal-units"></emu-xref> whose “Value” column contains _value_. If there is no such row, throw a RangeError exception.
	1. If _category_ is ~date~ and _unitGroup_ is ~date~ or ~datetime~, return ~unused~.
	1. If _category_ is ~time~ and _unitGroup_ is ~time~ or ~datetime~, return ~unused~.
	1. Throw a RangeError exception.

[gibson042]

This doesn't look right to me... if largestUnit is ~unset~, wouldn't ValidateTemporalUnitValue(largestUnit, unitGroup) have already rejected it?

Suggested change

	1. Perform ? ValidateTemporalUnitValue(_largestUnit_, _unitGroup_).
	1. If _largestUnit_ is ~unset~, then
	1. Set _largestUnit_ to ~auto~.
	1. If _largestUnit_ is ~unset~ or ~auto~, set _largestUnit_ to ~auto~.
	1. Else, perform ? ValidateTemporalUnitValue(_largestUnit_, _unitGroup_).

And likewise for the other call sites.

[gibson042]

As noted above, it seems like these calls will reject ~unset~ values.