This test checks the fix for golang/go#64547: the lostcancel analyzer reports
diagnostics that overflow the file.
-- p.go --
package p
import "context"
func _() {
_, cancel := context.WithCancel(context.Background()) //@diag("_, cancel", re"not used on all paths")
if false {
cancel()
}
} //@diag("}", re"may be reached without using the cancel")