This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-12-06
[Moved to DR at the February, 2014 meeting.]
According to 13.10.3.6 [temp.deduct.type] paragraph 17,
If, in the declaration of a function template with a non-type template-parameter, the non-type template-parameter is used in an expression in the function parameter-list and, if the corresponding template-argument is deduced, the template-argument type shall match the type of the template-parameter exactly, except that a template-argument deduced from an array bound may be of any integral type.
This does not cover return types, leaving the outcome of an example like the following unclear:
template <int N> struct A; template <short N> A<N> *foo(); void bar() { A<1> *(*fp)(void) = &foo; }
Proposed resolution (September, 2013):
Change 13.10.3.6 [temp.deduct.type] paragraph 17 as follows:
If, in the declaration of a function template with a non-type template-parameter, the non-type template-parameter is used in an expression in the function parameter-list and, if the corresponding template-argument is deduced, the template-argument type shall match the type of the template-parameter exactly, except that a template-argument deduced from an array bound may be of any integral typeP has a form that contains <i>, and if the type of the corresponding value of A differs from the type of i, deduction fails. If P has a form that contains [i], and if the type of i is not an integral type, deduction fails.147 [Example:...