This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

1006. std::nullptr_t as a non-type template parameter

[Voted into the WP at the November, 2010 meeting.]

std::nullptr_t is not currently allowed by 13.2 [temp.param] paragraph 4 to be used as the type of a non-type template parameter. However, this could arise for a template with a non-type template parameter with a dependent type in a template intended for use with pointers, e.g.,

    template<typename T, T t> void f();
    ...
    f<std::nullptr_t, nullptr>();

or in a case of delegation.

Proposed resolution (September, 2010):

Change 13.2 [temp.param] paragraph 4 as follows:

A non-type template-parameter shall have one of the following (optionally cv-qualified) types:

• integral or enumeration type,

• pointer to object or pointer to function,

• lvalue reference to object or lvalue reference to function,

• pointer to member.,

• std::nullptr_t.