Go module go directive

[kpurdon]

Following up on #394 I wanted to track figuring out how to properly set the go directive.

An issue has been filed that provides some clarity.

Of note:

The basic guideline is fairly simple: a "go" directive 1.N means that the code in that module is permitted to use language features that existed in 1.N even if those features were removed in later releases of the language.

So the directive is really important only after features are removed from Go in a new version. Since this is not an issue currently I think we should set the directive to the current version go 1.12.

The only thing to note is that there was a bug in Go 1.11.0 -> 1.11.3 (fixed in 1.11.4) that prevents builds for modules with the go 1.12 directive. I'm personally OK with that, but it's not my call.

Again, happy to open a PR, wanted to raise the issue first.

[kpurdon]

I guess to add to this the README states:

This library supports two most recent Go release series, currently 1.10 and 1.11.

So perhaps this directive should be go 1.11 and 1.10 support should be dropped. Then update to go 1.12 when 1.13 is released and 1.11 is dropped, ...

[streadway]

Is a viable alternative to only add the go 1.12 directive to the go.mod when version 1.14 is released and leave it empty until then?

[kpurdon]

I'd suggest just leaving it as is, and then updating to go 1.12 when 1.13 is released and this module drops <1.12 support.