func (check *Checker) isTerminating(s syntax.Stmt, label string) bool {
	switch s := s.(type) {
	default:
		panic("unreachable")

	case *syntax.DeclStmt, *syntax.EmptyStmt, *syntax.SendStmt,
		*syntax.AssignStmt, *syntax.CallStmt:
		// no chance

	case *syntax.LabeledStmt:
		return check.isTerminating(s.Stmt, s.Label.Value)

	case *syntax.ExprStmt:
		// calling the predeclared (possibly parenthesized) panic() function is terminating

		// case *LabeledStmt:
		// case *BlockStmt:
		// case *ExprStmt:
		case *SendStmt:
			m = n.Chan
		// case *DeclStmt:
		case *AssignStmt:
			m = n.Lhs
		// case *BranchStmt:
		// case *CallStmt:
		// case *ReturnStmt:
		// case *IfStmt:
		// case *ForStmt:
		// case *SwitchStmt:
		// case *SelectStmt:

		// helper nodes
		case *RangeClause:
			if n.Lhs != nil {
				m = n.Lhs
				continue

	// and reject that more efficiently though.
	return p.pexpr(nil, true)
}

// callStmt parses call-like statements that can be preceded by 'defer' and 'go'.
func (p *parser) callStmt() *CallStmt {
	if trace {
		defer p.trace("callStmt")()
	}

	s := new(CallStmt)
	s.pos = p.pos()
	s.Tok = p.tok // _Defer or _Go
	p.next()

	f(func() {
		runtime.deferprocat(func() { print("A") }, #defers)
	})

For this rewriting phase, we insert the explicit initialization of
#defers and then attach the #defers variable to the CallStmt
representing the defer. That variable will be propagated to the
backend and will cause the backend to compile the defer using
deferprocat instead of an ordinary deferproc.

			return
		}

		var x operand
		check.binary(&x, nil, lhs[0], rhs[0], s.Op)
		check.assignVar(lhs[0], nil, &x, "assignment")

	case *syntax.CallStmt:
		kind := "go"
		if s.Tok == syntax.Defer {
			kind = "defer"
		}
		check.suspendedCall(kind, s.Call)

	case *syntax.ReturnStmt:
		res := check.sig.results