How to include a file in cpp as both a string and code?

So I would like to have a file that I can conditionally include as either code or a string. Like this:

#define something
#include "myfile.inc" 

#undef something
const char myfileasastring = 
#include "myfile.inc" 

myfile.inc would be simple code like this:

something // anything extra here is fine as long as it goes away in the code include case
int myfunc() { return 23; } 

Is this possible? I tried having #define something R("mystring and start myfile with it but that does not seem to work.

My specific use case for this is a GLSL shader that, when running under GL I need as a string to pass to the GL driver but when running it in software emulation I want to compile it as CPP code.

I would love to have the same file for both cases. I know many workarounds on the project/make/build level, and even just cut and paste is not terrible, but it would be neat to have a portable compiler level way of doing this.