Zero length/capacity makes about lint

[dsymonds]

They were intentionally omitted because they don't occur very much in
practice, and the var x = ... form can occur at package-level, which
might matter more.

[zimmski]

I did some searching and found two occurrences in the Go source:

http://golang.org/src/pkg/encoding/json/decode.go#L808 -> this is the usual case where make can be removed
http://golang.org/src/pkg/regexp/exec.go#L415 -> Looks to me that this is an optimization because of the API. Every caller of Regexp.doExecute returns nil if there is no match. If there are 0 captures in a regex it can still match and it therefore needs to be not nil. It simply saves the slice header allocation for 0-capture regexes. This looks to me like the big exception.

[dsymonds]

Ultimately this comes down to avoiding too many false positives. Golint can't deduce whether a nil slice can truly be an adequate substitute for an allocated empty slice, so lintMake only looks for constructions that relatively new Go programmers seem to commonly write. It's not intended to capture every possible situation. In my experience of reviewing millions of lines of Go code, I think we've got the balance on this approximately right.