[Bug c++/69016] New: In C++14 standard, function with auto as return and arguments returns result with the datatype of first argument only

[emailstorbala at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69016

            Bug ID: 69016
           Summary: In C++14 standard, function with auto as return and
                    arguments returns result with the datatype of first
                    argument only
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: emailstorbala at gmail dot com
  Target Milestone: ---

Hi Team,

I am using gcc/g++ 4.9.2 version in Debian 8.2. I tried to compile the below
code using the compiler option:

g++ -std=c++14 -s -O3 test.cpp -o test

----------------------------------------------------

#include <iostream>

using namespace std;

auto GetSum(auto a, auto b)
{
    return (a + b);
}


int main()
{
    auto temp = GetSum(10, 20.5);
    cout << "The sum is " << temp << endl;

    return 0;
}

----------------------------------------------------

Result:
The sum is 30

If the code is changed to 

----------------------------------------------------

#include <iostream>

using namespace std;

auto GetSum(auto a, auto b)
{
    return (a + b);
}


int main()
{
    auto temp = GetSum(10.5, 20);
    cout << "The sum is " << temp << endl;

    return 0;
}

----------------------------------------------------

Result:
The sum is 30.5

Issue: The function GetSum() returns value of the first data type only rather
than the final value's datatype. (Even if I set - auto GetSum(auto a, auto b)
-> double)

Please let me know if I am doing anything wrong.