Implementing UINT64_C in GLSL

I'd like to reuse a C header file in GLSL that makes use of the UINT64_C() macro. To make this work in GLSL, I'm enabling the GL_ARB_gpu_shader_int64 extension and defining UINT64_C() as follows:

`#define UINT64_C(x) x##ul`

Unfortunately, when the macro argument is a 64-bit value, the compiler generates the "hexadecimal literal too big" error before the macro is expanded. E.g.:

`#define BLAH UINT64_C(0x12345678912);`

Is this a bug or is this the intended behaviour?

Thanks,
Dae

Reproduce the reported case using the UINT64_C and BLAH macro definitions with GL_ARB_gpu_shader_int64 enabled. Trace preprocessing and hexadecimal-literal validation to determine whether the diagnostic occurs before macro expansion; done means establishing the intended behavior and documenting or correcting it with a regression check.

Written by the indexing model from the issue text.