by mzannone:

-- Before filing a bug, please check whether it has been fixed since
-- the latest release: run "hg pull -u" and retry what you did to
-- reproduce the problem.  Thanks.

Done

-- What steps will reproduce the problem?

$ cd /usr/local/go/src/cmd/goyacc
$ make clean
rm -f *.[568vq] goyacc 
$ make units
/Users/z4nn/bin/6g -o _go_.6 goyacc.go 
/Users/z4nn/bin/6l -o goyacc _go_.6 
./goyacc units.y
6g y.go
y.go:36: syntax error near Node
y.go:43: syntax error near Var
y.go:244: syntax error near int
y.go:279: empty top-level declaration
y.go:292: empty top-level declaration
y.go:311: syntax error near main
y.go:393: syntax error near bool
y.go:408: syntax error near bool
y.go:419: syntax error near v
y.go:441: syntax error near Node
y.go:441: fatal error: too many errors
make: *** [units] Error 1

-- What is your $GOOS?  $GOARCH?

$ env | grep GO
GOARCH=amd64
GOROOT=/usr/local/go
GOOS=darwin

-- Which revision are you using?  (hg identify)

$ hg identify
683ed10f7832 tip

-- Please provide any additional information below.

Probably goyacc implementation is not yet in sync with the semicolons syntax change