How to show the current #pragma pack setting in C++?

Question

Here is an example how to set the current #pragma pack:

#pragma pack(4)

How is it possible to show the current #pragma pack setting?

Answer 1

With Microsoft's C++ compiler you can use

#pragma pack(show)

which causes the compiler to issue a warning containing the value.

Note this is not standard C++ (and neither is any guise of #pragma pack) so other compilers may or may not have this feature. At the time of writing GCC, for example, doesn't.

Answer 2

For Microsoft Visual C++ use

#pragma pack(show)

It will generate the following compiler warning:

Warning C4810   value of pragma pack(show) == 4