模板非类型参数 [英] template non type arguments

问题描述

$ 14.3.2 - ...非模板，非模板模板参数的模板参数应为以下之一：

$14.3.2 - "... A template-argument for a non-type, non-template template-parameter shall be one of:

...一个常量表达式（5.19），用于指定具有静态存储持续时间和外部或内部链接或具有外部或内部链接的函数...

...a constant expression (5.19) that designates the address of an object with static storage duration and external or internal linkage or a function with external or internal linkage..."

在下面显示的代码中，和'name3'不允许作为非类型模板参数。我在Windows上使用gcc 4.7.2。

In the code shown below, I fail to understand why 'name2' and 'name3' are not allowed as non type template arguments. I am using gcc 4.7.2 on Windows.

'name2'和'name3'都是数组的名称，因此是常量表达式。另外'name2'具有内部链接，'name3'具有静态和内部链接。

Both 'name2' and 'name3' are names of array and hence are constant expressions. Further 'name2' is having internal linkage and 'name3' has both static and internal linkage.

template<char const *p> void f()
{

}

char name1[] = "Hi";
static char name2[]= "Hi";
const static char name3[]= "Hi";
char *name4 = "Hi";

int main()
{
    f<name1>();
    f<name2>();
    f<name3>();
    f<name4>();
}

推荐答案

这是一个实现bug，而不是标准的一个深奥的角落。

As @Nawaz correctly guessed, this is an implementation bug, not an esoteric corner of the standard.

具体来说，gcc似乎有麻烦。除了最后的 name4 这是违反标准，其余的编译正确与 clang

Specifically, gcc seems to have trouble with it. Barring the last name4 which is against the standard, the rest of it compiles fine with clang

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