clang-tidy - cert-dcl21-cpp — Extra Clang Tools 8 documentation

# Extra Clang Tools 8 documentation

## clang-tidy - cert-dcl21-cpp

# cert-dcl21-cpp

This check flags postfix `operator++` and `operator--` declarations if the return type is not a const object. This also warns if the return type is a reference type.

This check corresponds to the CERT C++ Coding Standard recommendation DCL21-CPP. Overloaded postfix increment and decrement operators should return a const object.