问题描述
请考虑以下代码：
template<int* a>
class base {};
int main()
{
base<(int*)0> test;
return 0;
}
Comeau和MSVC编译时没有问题（Comeau警告变量），而GCC在 base 上失败。测试; 行，说明
Both Comeau and MSVC compile this without issues (except for Comeau warning about an unused variable), while GCC fails on the base<(int*)0> test; line, stating
模板参数1无效
它抱怨究竟是什么？谁是对的 - 这段代码应该编译吗？值得注意的是，我的GCC版本是非常 old（3.4.2），所以可能与它有关。感谢。
What exactly is it complaining about? And who's right -- should this code compile? It's worth noting that my GCC version is extremely old (3.4.2) so that may have something to do with it. Thanks.
推荐答案
从（着重号添加）：
14.1.3 A non-type template-parameter shall have one of the following (option-
ally cv-qualified) types:
...
--pointer to object, accepting an address constant expression desig-
nating a named object with external linkage,
...
显然，使用空指针来实例化模板是不合法的，因为空指针不会指向具有外部链接的命名对象。
Apparently, it's not legal to instantiate a template with a null pointer, as a null pointer doesn't point to a "named object with external linkage".
这篇关于将指针作为模板参数：Comeau& MSVC编译，GCC失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！