Yeah, I meant #if directives, like static_assert. I asked it to help me statically verify my assumptions about the ELF format and it gave me some pretty insane code. Here's the excerpt:

> Certainly, you can use a combination of sizeof and #error directives for conditional compilation to achieve a similar effect without static_assert.

  // Compile-time check for structure sizes
  #if sizeof(Elf32_Phdr) != sizeof(((Elf32_Ehdr*)0)->e_phentsize)
      #error "32-bit structure size mismatch"
  #endif

  #if sizeof(Elf64_Phdr) != sizeof(((Elf64_Ehdr*)0)->e_phentsize)
      #error "64-bit structure size mismatch"
  #endif

> In this example, if the structure sizes don't match, the preprocessor will generate an error at compile time using the #error directive.

> I didn't know sizeof could be used with the C preprocessor

> Yes, sizeof can be used in certain contexts within the C preprocessor.

> It's commonly employed in combination with the #if and #error directives to perform compile-time checks on sizes or other constants.

> This usage allows you to catch potential issues during compilation rather than at runtime.

I should probably go sleep a bit before I embarrass myself any further. After nearly 24 hours awake it seems I have lost the ability to tell macros and directives apart.