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Compiler warning (level 4) C5054

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operator 'operator-name': deprecated between enumerations of different types

Remarks

C++20 has deprecated the usual arithmetic conversions on operands, where one operand is of enumeration type and the other is of a different enumeration type. For more information, see C++ Standard proposal P1120R0.

In Visual Studio 2019 version 16.2 and later, an implicit conversion between enumeration types produces a level 4 warning when the /std:c++latest compiler option is enabled. In Visual Studio 2019 version 16.11 and later, it also produces a warning under /std:c++20.

Example

In Visual Studio 2019 version 16.2 and later, the following code produces a level 4 warning when the /std:c++latest compiler option is enabled. In Visual Studio 2019 version 16.11 and later, it also produces a warning under /std:c++20:

// C5054.cpp
// Compile using: cl /EHsc /W4 /std:c++latest C5054.cpp
enum E1 { a };
enum E2 { b };
int main() {
    int i = a | b; // warning C5054: operator '|': deprecated between enumerations of different types
}

To avoid the warning, use static_cast to convert the second operand:

// C5054_fixed.cpp
// Compile using: cl /EHsc /W4 /std:c++latest C5054_fixed.cpp
enum E1 { a };
enum E2 { b };
int main() {
  int i = a | static_cast<int>(b);
}