From: Sidney Marshall <sidneym@frontiernet.net>
To: gcc-help@gcc.gnu.org
Cc: sidneym@frontiernet.net
Subject: C++11 - Parameter pack question
Date: Sat, 16 Aug 2014 01:14:00 -0000 [thread overview]
Message-ID: <20140816011400.3iBs42xNNekF2rFq0-ly_ssZriEKwKePpC1FOl3EBIM@z> (raw)
Hello,
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: âsumâ function uses
âautoâ type specifier without trailing return type [enabled by default]
auto sum(T value, U ... values) {
$ ./a.exe
7.6
de
-------------------------------------------
All of my attempts to use a trailing return type
failed (and I believe should have failed according to the standard).
My two questions:
1. What possible user mistake is the warning worried about?
2. How can I write my code with better style so that there is no warning?
Thank you.
--Sidney Marshall
next reply other threads:[~2014-08-16 1:14 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-16 1:14 Sidney Marshall [this message]
2014-08-16 1:14 Sidney Marshall
[not found] <201408160114.s7G1EKDO087976@nef2.ens.fr>
2014-08-16 7:12 ` Marc Glisse
[not found] ` <alpine.DEB.2.11.1408160907210.1729@laptop-mg.saclay.inria. fr>
2014-08-17 2:28 ` Sidney Marshall
2014-08-17 2:28 ` Sidney Marshall
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