Thanks for the report.

In $ go generate -h:

[...]
Note that go generate does not parse the file, so lines that look
like directives in comments or multiline strings will be treated
as directives.
[...]

Closing this, since it's not a bug.

that might want to be re-evaluated. its odd and unexpected behaviour (even if documented). is there a reason for this choice?

I guess that one reason may be the fact that doing it this way does not require parsing the file. The doc hints at this:

Note that go generate does not parse the file

If you want a more authoritative answer, I think the right place to ask this is golang-dev: https://groups.google.com/forum/#!forum/golang-dev (we don't usually use the issue tracker for discussion).