cmake check if a public field exist in class

Question

// some_library.h
class MyLib {
  public:
  int field_a;
  int field_b; // Only available on some versions
  int field_c; // Only available on some versions
  int ...;
};

A library I'm using have a variable number of public fields depending on versions. In Cmake, is it possible to detect if a certain field from library header exists? (perhaps similar to the CHECK_FUNCTION_EXISTS)

Answer 1

You can use check_symbol_exists for a C symbol.

Doc: https://cmake.org/cmake/help/latest/module/CheckSymbolExists.html

Or check_cxx_symbol_exists for a CXX symbol.

Doc: https://cmake.org/cmake/help/v3.18/module/CheckCXXSymbolExists.html

You can use check_struct_has_member from CheckStructHasMember. See https://cmake.org/cmake/help/latest/module/CheckStructHasMember.html

CMakeLists.txt

include(CheckStructHasMember)
Check_struct_has_member("class MyLib" field_a ${CMAKE_CURRENT_SOURCE_DIR}/MyLib.h HAS_FIELD_A LANGUAGE CXX)