The -json and -c=N flags, formerly belonging only to the
go/packages-based {single,multi}checkers, are now supported by
unitchecker as well.
The no-op -source, -v, -all, and -tags flags, formerly belonging only
to unitchecker, have moved to the analysisflags package, which is
common to all checkers.
The -flags flag now reports all registered flags (except the
{single,multi}checker-only debugging flags) rather than just those
related to analyzers, allowing one to say: 'go vet -json' or 'go vet -c=1'.
The code for printing diagnostics, either plain or in JSON, has been
factored and moved into the common analysisflags package.
This CL depends on https://go-review.googlesource.com/c/go/+/149960 to
cmd/go, which causes 'go vet' to populate the ID field of the *.cfg.
This field is used as a key in the JSON tree.
Added basic tests of the new -json and -c unitchecker flags.
Change-Id: Ia7a3a9adc86de067de060732d2c200c58be3945a
Reviewed-on: https://go-review.googlesource.com/c/150038
Reviewed-by: Michael Matloob <matloob@golang.org>
8e5aba0a36