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.

What steps will reproduce the problem?
1. Read the spec
2. Try the code, just to be sure: both gofmt and 8g reject it

What is the expected output? What do you see instead?
In spec, expected:
switch x := f(); {  // missing switch expression means "true"
case x < 0: return -x
default: return x
}

Found:
switch x := f() {  // missing switch expression means "true"
case x < 0: return -x
default: return x
}

http://golang.org/doc/go_spec.html#Switch_statements

What is your $GOOS?  $GOARCH?
linux 386

Which revision are you using?  (hg identify)
cf3701cfac15 tip

Please provide any additional information below.
Unless the implementation is wrong, and you are supposed to be able to 
elide the ';' after the simple statement (though this seems unlikely). 
Either way, there's a discord.