const enum should allow "Infinity" as a valid name

[speigg]

    declare const enum CameraDeviceFocusMode {
        Normal = 0,
        TriggerAuto = 1,
        ContinuousAuto = 2,
        Infinity = 3, // <- error: An enum cannot have a numeric name
        Macro = 4
    }

[RyanCavanaugh]

This is intentional because Infinity is also a valid enum value; we disallow any name that might be a value because the lookup object only works if no names are values and no values are names.

Recommended fix is to just use Infinite instead of Infinity

[speigg]

What is the lookup object exactly? Using the name Infinity as a property key is completely valid in javascript by the way.

[RyanCavanaugh]

I missed that this enum was const. We don't need to enforce this rule for those.

[RyanCavanaugh]

(Lookup object, see http://stackoverflow.com/a/28818850/1704166)

[speigg]

Not enforcing that rule for const enum sounds great.

[RyanCavanaugh]

Approved even for non-const enums.

The suggested implementation was to skip any leading -, then see if the next (or first) character is a digit. Only names matching this rule should be subject to restriction. This should allow Infinity and NaN but still disallow names like 5.

[DanielRosenwasser]

So what's the new rule now for numeric names? Same as before but make a special exception for "Infinity" and "NaN"?

Also @jmatthiesen asked about this a while back.

[RyanCavanaugh]

Same as before but make a special exception for "Infinity" and "NaN"?

Correct (as well as -Infinity)

[YuichiNukiyama]

@RyanCavanaugh A JavaScript identifier must start with a letter, underscore (_), or dollar sign ($);. So, I think -Infinity is invalid.

[RyanCavanaugh]

Enum members need not be identifiers - they can be quoted much like the property names in object literals

[jbondc]

Reported here too #3572