What std functions are CTFE?

[Borislav Kosharov]

How do I know which functions are CTFE? I mean from the ones in 
std. I think there should be some icon or marker in the docs that 
indicates which function can be called during compilation.

I remember that there was a compile time bool that checks if the 
current function is called during compilation(__ctfe I think). 
But that is used only in the implementation of the function. Is 
there some kind of attribute(@ctfe for ex) that forces the 
compiler to check if the function is @ctfe without using it 
anywhere.

I would really like to see the std documented in a more pleasant 
visual way. By using icons that replace the long declarations of 
the functions(something like MSDN maybe).

If such documenting tool exists please tell. I know for DDoc, 
bootDoc and others, but none of them(not sure) can replace 
attributes like @property, pure, static and others with icons.