title: "Compiler Error C2672 | Microsoft Docs"

ms.date: "10/24/2017"

ms.technology: ["cpp-tools"]

ms.topic: "error-reference"

f1_keywords: ["C2672"]

dev_langs: ["C++"]

helpviewer_keywords: ["C2672"]

ms.assetid: 7e86338a-2d4b-40fe-9dd2-ac6886f3f31a

author: "corob-msft"

ms.author: "corob"

manager: "ghogen"

The compiler could not find an overloaded function that matches the specified function. No function was found that takes matching parameters, or no matching function has the required accessibility in context.

When used by certain standard library containers or algorithms, your types must provide accessible members or friend functions that satisfy the requirements of the container or algorithm. For example, your iterator types should derive from `std::iterator<>`. Comparison operations or use of other operators on container element types may require the type be considered as both a left-hand and a right-hand operand. Use of the type as a right-hand operand can require implementation of the operator as a non-member function of the type.

Versions of the compiler before Visual Studio 2017 did not perform access checking on qualified names in some template contexts. This can interfere with expected SFINAE behavior where the substitution is expected to fail due to the inaccessibility of a name. This could have potentially caused a crash or unexpected behavior at runtime due to the compiler incorrectly calling the wrong overload of the operator. In Visual Studio 2017, a compiler error is raised.

This example compiles in Visual Studio 2015 but raises an error in Visual Studio 2017. To fix this issue, make the template parameter member accessible where it is evaluated.

#include <type_traits>

template <class T> class S {

// public: // Uncomment this line to fix

typedef typename T type;

};

template <class T, std::enable_if<std::is_integral<typename S<T>::type>::value, T> * = 0>

bool f(T x)

{

return (x == 0);

}

int main()

{

f(10); // C2672: No matching overloaded function found.

}

title: "Compiler Error C3615 | Microsoft Docs"

ms.date: "10/24/2017"

ms.technology: ["cpp-tools"]

ms.topic: "error-reference"

f1_keywords: ["C3615"]

dev_langs: ["C++"]

helpviewer_keywords: ["C3615"]

ms.assetid: 5ce96ba9-3d31-49f3-9aa8-24e5cdf6dcfc

author: "corob-msft"

ms.author: "corob"

manager: "ghogen"

The function *function* could not be evaluated as `constexpr` at compile time. To be `constexpr`, a function can only call other `constexpr` functions.

Visual Studio 2017 correctly raises an error when the left-hand operand of a conditionally evaluating operation is not valid in a `constexpr` context. The following code compiles in Visual Studio 2015 but not in Visual Studio 2017.

template<int N>

struct myarray

{

int size() const { return N; }

};

constexpr bool f(const myarray<1> &arr)

{

return arr.size() == 10 || arr.size() == 11; // C3615 starting in Visual Studio 2017

}

ms.date: "10/25/2017"

If a type is marked [sealed](../../windows/sealed-cpp-component-extensions.md) and [abstract](../../windows/abstract-cpp-component-extensions.md), it can only have static members.

This warning is automatically promoted to an error. If you wish to modify this behavior, use [#pragma warning](../../preprocessor/warning.md).

The following sample generates C4693.

public ref class Public_Ref_Class sealed abstract {

public:

void Test() {} // C4693

static void Test2() {} // OK

};

ms.date: "10/25/2017"

An abstract and sealed class cannot inherit from a reference type; a sealed and abstract class can neither implement the base class functions nor allow itself to be used as a base class.

For more information, see [abstract](../../windows/abstract-cpp-component-extensions.md), [sealed](../../windows/sealed-cpp-component-extensions.md), and [Classes and Structs](../../windows/classes-and-structs-cpp-component-extensions.md).

This warning is automatically promoted to an error. If you wish to modify this behavior, use [#pragma warning](../../preprocessor/warning.md).

The following sample generates C4694.

ref struct A {};

ref struct B sealed abstract : A {}; // C4694

ms.date: "10/26/2017"

The elements of a braced initializer list are to be evaluated in left-to-right order. There are two cases in which the compiler is unable to guarantee this order: the first is when some of the elements are objects passed by value; the second is when compiling with `/clr` and some of the elements are fields of objects or are array elements. When the compiler can't guarantee left-to-right evaluation it emits warning C4868.

This warning can be generated as a result of compiler conformance work that was done for Visual C++ 2015 Update 2. Code that compiled prior to Visual C++ 2015 Update 2 can now generate C4868.

This warning is off by default. Use `/Wall` to activate this warning.

To resolve this warning, first consider whether left-to-right evaluation of the initializer list elements is necessary, such as when evaluation of the elements might produce order-dependent side-effects. In many cases, the order in which elements are evaluated does not have an observable effect.

If the order of evaluation must be left-to-right, consider if it's possible to pass the elements by `const` reference instead. A change such as this eliminates the warning in the following code sample.

This sample generates C4868, and shows a way to fix it:

#include <cstdio>

class HasCopyConstructor

{

public:

int x;

HasCopyConstructor(int x): x(x) {}

HasCopyConstructor(const HasCopyConstructor& h): x(h.x)

{

printf("Constructing %d\n", h.x);

}

};

class TripWarning4868

{

public:

// note that taking "HasCopyConstructor" parameters by-value will trigger copy-construction.

TripWarning4868(HasCopyConstructor a, HasCopyConstructor b) {}

// This variation will not trigger the warning:

// TripWarning4868(const HasCopyConstructor& a, const HasCopyConstructor& b) {}

};

int main()

{

HasCopyConstructor a{1};

HasCopyConstructor b{2};

// the warning will indicate the below line, the usage of the braced initializer list.

TripWarning4868 warningOnThisLine{a, b};

};

ms.date: "10/25/2017"

The current version of Visual C++ does not use this keyword.

This warning is automatically promoted to an error.