force that part of a c++ compiled as C

Question

I want to define a struct in a c++ source code that should be a POD (so it should be compiled based on C standard and not C++)

for example assume that I have the following code inside a c++ file:

struct myStruct
{
   int x;
   int y;
}
class MyClass
{
    int x;
    int y;
}

if I compile this code, struct is POD and should be compiled as POD. So the placement of member variables follow the C standard which is well defined.

But assume that a user may mistakenly, change the code to this code:

struct myStruct
{

   int x;
   int y;
private:
   int z;
}
class MyClass
{
    int x;
    int y;
}

now the struct is not POD and compiler is free on how it would place the member variables in memory.

How can I force the compiler to make sure that a struct is always compiled based on C standard?

Please note that I can not place the code inside a *.c code as I am developing a header only code which can be included into a *.cpp source code.

Answer 1

You can't force the translator to treat it "as C". But you can add an assertion that it is compatible with C code.

#include <type_traits>

struct myStruct
{
   int x;
   int y;
};

static_assert(std::is_pod_v<myStruct>, "Violated POD-ness of myStruct!");