https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103740
Bug ID: 103740
Summary: A function template declaration with a
template-parameter in the last that has no default
argument or can be deduced shall be ill-formed
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: xmh970252187 at gmail dot com
Target Milestone: ---
template<class... T, class U> void g() { }
This template declaration should be ill-formed since it violates [temp.param]
p14
A template parameter pack of a function template shall not be followed by
another template parameter unless that template parameter can be deduced from
the parameter-type-list ([dcl.fct]) of the function template or has a default
argument ([temp.deduct]).
Template parameter `U` satisfies none of them, hence the declaration should be
ill-formed. It is also a formal example that the comment says it is an error.
