This patch to the Go compiler improves the error message for the invalid use of a special builtin function like unsafe.Sizeof. Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu. Committed to mainline.
Ian
diff -r c1acc6a7e12a go/expressions.cc --- a/go/expressions.cc Mon Jan 23 15:53:43 2012 -0800 +++ b/go/expressions.cc Mon Jan 23 22:58:26 2012 -0800 @@ -1328,7 +1328,8 @@ // can't take their address. if (fntype->is_builtin()) { - error_at(this->location(), "invalid use of special builtin function %qs", + error_at(this->location(), + "invalid use of special builtin function %qs; must be called", this->function_->name().c_str()); return error_mark_node; }