CODEWITHSUNDEEP
c++11lambdavisual-studio-2015stl
Aleph0
Aleph0

Reputation: 6084

Compiler error C3538 in Visual Studio using std::bind

I have problems to compile the following small code fragment. Visual Studio 2015 has problems in the deduction of the type of remover. Can someone explain me why and how to fix this error?

My idea was to create a reuseable function deleting the first occurence of a value in a given STL container under some user definable predicate.

#include <algorithm>
#include <iostream>
#include <iterator>
#include <functional>
#include <vector>

template<typename T>
auto removeOnlyOnce = [](std::vector<T>& v, const std::function<bool(const T&)>& pred) {
    auto iter = std::find_if(v.begin(), v.end(), pred);
    if (iter != v.end()) {
        v.erase(iter);
    }
};

int main(int argc, char** args) {
    std::vector<int> v{ 1,2,3,4,2,2,3 };

    // Works
    std::function<bool(const int&)> isTwoPred = [](int x) { return x == 2; };
    removeOnlyOnce<int>(v, isTwoPred);

    // Also works
    removeOnlyOnce<int>(v, [](const int x)->bool { return x == 2; });

    // Gives compile error: C3538
    // auto remover = std::bind(removeOnlyOnce<int>, v, std::placeholders::_1);
    // remover([](const int x)->bool { return true; });

    std::copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
}

The compiler issues the following warning:

main.cpp(26): error C3538: In einer Deklaratorliste muss "auto" immer in denselben Typ hergeleitet werden.
main.cpp(26): note: kann "<lambda_d00b55a1f2cac59f0efd4a81f45edea3>" sein
main.cpp(26): note: oder "std::_Binder<std::_Unforced,<lambda_d00b55a1f2cac59f0efd4a81f45edea3> &,std::vector<int,std::allocator<_Ty>> &,const std::_Ph<1> &>"
    with
    [
        _Ty=int
    ]

Compiling with Wandbox and Option C++11 gives the following warning, which might be important:

prog.cc:8:6: warning: variable templates are a C++14 extension [-Wc++14-extensions]
auto removeOnlyOnce = [](std::vector<T>& v, const std::function<bool(const T&)>& pred) {
     ^
1 warning generated.

Upvotes: 0

Views: 68

Answers (1)

Kaveh Vahedipour
Kaveh Vahedipour

Reputation: 3477

This lambda is not local. Please omit the & in [&] and you should be fine. Maybe a little cryptic, what I wrote: In other words, you don't have a this to capture.

Upvotes: 1

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