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Date: Sat, 16 Aug 2014 07:12:00 -0000
From: Marc Glisse <marc.glisse@inria.fr>
Reply-To: gcc-help@gcc.gnu.org
To: Sidney Marshall <sidneym@frontiernet.net>
cc: gcc-help@gcc.gnu.org
Subject: Re: C++11 - Parameter pack question
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On Fri, 15 Aug 2014, Sidney Marshall wrote:

> The following code compiles and runs correctly but gives a warning:
>
> ----------------------------------------
> #include<iostream>
>
> using namespace std;
>
> template<class T>
> T sum(T value) {
>  return value;
> }
>
> template<class T, class ... U>
> auto sum(T value, U ... values) {
>    return value + sum(values ...);
> }
>
> int main() {
>  cout << sum(1, 2, 4.6) << endl;
>  cout << sum(1, "abcde", 2) << endl;
> }
> --------------------------------------
>
> $ g++ -std=c++11 pack.cpp
> pack.cpp:11:31: warning: â??sumâ?? function uses â??autoâ?? type specifier 
> without trailing return type [enabled by default]
> auto sum(T value, U ... values) {

The warning should probably specify that this is a C++14 feature. You 
should be compiling with -std=c++1y.

-- 
Marc Glisse