Incorrect Overload Resolution | Microsoft Connect

Incorrect Overload Resolution by WorkingHorse

Closed

as Fixed

Type:	Bug
ID:	606746
Opened:	9/29/2010 11:13:57 AM
Access Restriction:	Public

Workaround(s)

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User(s) can reproduce this bug

The C++ compiler cannot match the correct overload for the std::transform template in the algorithm library -- this is just one example, there are no doubt others where code that used to work in Visual Studio 2005 no longer works in 2010.

Details (expand)

Visual Studio 2010

Compatibility

Open up Visual Studio 2010 and create a C++ project using the Win32 Console Application wizard. Then, enter the following code in your main .cpp file:

#include <vector>
#include <map>
#include <algorithm>
#include <iterator>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    vector<string> a;
    vector<string> b;
    map<string, string> c;

    // Populate vectors

    transform(a.begin(), a.end(), b.begin(), inserter(c, c.begin()), make_pair<string, string>);

    return 0;
}

Finally, attempt to compile this program.

English

Windows XP

English

The compiler fails with the following error sequence:

1>------ Build started: Project: Test Vector To Map, Configuration: Debug Win32 ------
1> Test Vector To Map.cpp
1>c:\test vector to map\test vector to map.cpp(22): error C2784: '_OutTy *std::transform(_InIt1,_InIt1,_InTy (&)[_InSize],_OutTy (&)[_OutSize],_Fn2)' : could not deduce template argument for '_InTy (&)[_InSize]' from 'std::_Vector_iterator<_Myvec>'
1>         with
1>         [
1>             _Myvec=std::_Vector_val<std::string,std::allocator<std::string>>
1>         ]
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1293) : see declaration of 'std::transform'
1>c:\test vector to map\test vector to map.cpp(22): error C2784: '_OutTy *std::transform(_InIt1,_InIt1,_InIt2,_OutTy (&)[_OutSize],_Fn2)' : could not deduce template argument for '_OutTy (&)[_OutSize]' from 'std::insert_iterator<_Container>'
1>         with
1>         [
1>             _Container=std::map<std::string,std::string>
1>         ]
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1279) : see declaration of 'std::transform'
1>c:\test vector to map\test vector to map.cpp(22): error C2784: '_OutIt std::transform(_InIt1,_InIt1,_InTy (&)[_InSize],_OutIt,_Fn2)' : could not deduce template argument for '_InTy (&)[_InSize]' from 'std::_Vector_iterator<_Myvec>'
1>         with
1>         [
1>             _Myvec=std::_Vector_val<std::string,std::allocator<std::string>>
1>         ]
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1267) : see declaration of 'std::transform'
1>c:\test vector to map\test vector to map.cpp(22): error C2914: 'std::transform' : cannot deduce template argument as function argument is ambiguous
1>c:\test vector to map\test vector to map.cpp(22): error C2784: '_OutIt std::transform(_InIt1,_InIt1,_InIt2,_OutIt,_Fn2)' : could not deduce template argument for '_OutIt' from 'std::insert_iterator<_Container>'
1>         with
1>         [
1>             _Container=std::map<std::string,std::string>
1>         ]
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1249) : see declaration of 'std::transform'
1>c:\test vector to map\test vector to map.cpp(22): error C2780: '_OutTy *std::transform(_InIt,_InIt,_OutTy (&)[_OutSize],_Fn1)' : expects 4 arguments - 5 provided
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1127) : see declaration of 'std::transform'
1>c:\test vector to map\test vector to map.cpp(22): error C2780: '_OutIt std::transform(_InIt,_InIt,_OutIt,_Fn1)' : expects 4 arguments - 5 provided
1>         c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1111) : see declaration of 'std::transform'
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

The compiler should match the std::transform template against the definition:

template<class _InIt1,
    class _InIt2,
    class _OutIt,
    class _Fn2> inline
    _OutIt transform(_InIt1 _First1, _InIt1 _Last1,
        _InIt2 _First2, _OutIt _Dest, _Fn2 _Func);

0 attachments

Hi,

Thanks for reporting this bug. We've fixed it, and the fix will be available in VC11. Note that due to changes between C++98/03 and C++0x, you'll have to use either make_pair<string&, string&> or make_pair<const string&, const string&>. Here's an example:

C:\Temp>type meow.cpp
#include <algorithm>
#include <iostream>
#include <iterator>
#include <map>
#include <ostream>
#include <string>
#include <utility>
#include <vector>
using namespace std;

void print(const map<string, string>& m) {
    for (auto i = m.begin(); i != m.end(); ++i) {
        cout << "(" << i->first << ", " << i->second << ")" << endl;
    }
}

int main() {
    vector<string> series;
    series.push_back("TOS");
    series.push_back("TNG");
    series.push_back("DS9");
    series.push_back("VOY");
    series.push_back("ENT");

    vector<string> captains;
    captains.push_back("Kirk");
    captains.push_back("Picard");
    captains.push_back("Sisko");
    captains.push_back("Janeway");
    captains.push_back("Archer");

    map<string, string> m;

    transform(series.begin(), series.end(), captains.begin(), inserter(m, m.end()), make_pair<string&, string&>);

    print(m);

    cout << "-----" << endl;
    m.clear();

    const vector<string> vs = series;
    const vector<string> vc = captains;

    transform(vc.begin(), vc.end(), vs.begin(), inserter(m, m.end()), make_pair<const string&, const string&>);

    print(m);
}

C:\Temp>cl /EHsc /nologo /W4 meow.cpp
meow.cpp

C:\Temp>meow
(DS9, Sisko)
(ENT, Archer)
(TNG, Picard)
(TOS, Kirk)
(VOY, Janeway)
-----
(Archer, ENT)
(Janeway, VOY)
(Kirk, TOS)
(Picard, TNG)
(Sisko, DS9)

Also, please note that the STL's headers include each other in unspecified ways, so you should always be careful to include the headers that you need (e.g. <string> for string and <utility> for make_pair).

If you have any further questions, feel free to E-mail me at stl@microsoft.com .

Stephan T. Lavavej
Visual C++ Libraries Developer