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ReflectionFunction(Method)引用参数导致Invocation failed

今天同事反馈一个问题, PHP5.2.x在使用反射做函数包装的时候, 得到"Invocation failed"的异常, 而使用call_user_func代替则不会,
原逻辑太复杂, 经过精简以后可重现异常的代码如下(使用ReflectionFunction为例, ReflectionMethod类似):

function who(&$name) {
    echo $name;
$name = "laruence";
$method = new ReflectionFunction("who");
Uncaught exception 'ReflectionException' with message
'Invocation of function who() failed'

找原因过程中歧途我就不多言了, 最后跟踪到invokeArgs会调用Zend引擎提供的zend_call_function, 而在zend_call_function中, 有如下一段逻辑引起我的怀疑(注意注释部分):

int zend_call_function(zend_fcall_info *fci
         , zend_fcall_info_cache *fci_cache TSRMLS_DC) {
        if (ARG_SHOULD_BE_SENT_BY_REF(EX(function_state).function, i+1)
         && !PZVAL_IS_REF(*fci->params[i])) {
/*如果形参是引用传递 并且参数不是引用 */
            if ((*fci->params[i])->refcount>1) {
/*如果参数的refcount大于1 */
                zval *new_zval;
                if (fci->no_separation) {
/*如果不容许执行分离操作, 则返回失败 */
                    return FAILURE;

也就是说, 如果一个申明为引用传递的参数不为引用传递, 而refcount又大于1, 那么在不容许分离的条件下, 就会导致zend_call_function失败返回(如果对refcount和变量分离不了解, 可以参看我之前的文章深入理解PHP原理之变量分离/引用).
经过验证, 果然invokeArgs在构造zend_fcall_info fci的时候, 是禁止separation的, 所以导致zend_call_funcion返回FAILURE.
而使用call_user_func则不会是因为,call_user_function不考虑no_separation直接分离, 这一点在PHP手册中, call_user_func中是有说明的:

Note: Note that the parameters for call_user_func() are not passed by reference.

找到了原因, 那解决的办法, 也就容易了:

function who(&$name) {
    echo $name;
$name = "laruence";
$method = new ReflectionFunction("who");
$method->invokeArgs(array(&$name)); //is_ref


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