"Inf" and "+Inf" in Super JSON

[philrz]

tl;dr

At the moment the Super JSON spec indicates that both Inf and +Inf are ways to express "positive infinity", but only +Inf currently works. In the review comments of #5386 @mccanne expressed:

Regarding Inf, in IEEE floating point, there's a +Inf and a -Inf. I think we should have one way to represent +Inf in Super JSON and we could change +Inf to Inf. I think we went with +Inf because the golang fmt library prints it that way.

Details

Repro is with super commit 49b1add.

When working on docs updates in #5386, I noticed that only +Inf seems to be working at the moment.

$ super -version
Version: v1.18.0-71-g49b1addb

$ echo '1 +Inf 2' | super -z -c 'yield typeof(this)' -
<int64>
<float64>
<int64>

$ echo '1 Inf 2' | super -z -c 'yield typeof(this)' -
stdio:stdin: Super JSON syntax error

When we fix this we can make sure the Super JSON spec is updated to reflect the final state.