Improving version(...)

[Jonathan M Davis]

On Monday, October 18, 2010 12:24:48 Don wrote:
> And currently, you can make a typo like:
> version(Linix) {}
> and it compiles happily. I don't like that. Especially when we have
> builtin names like D_Inline_Asm_X86_64!

The real question is how to cleanly fix that. A version is defined only if it's in 
use, so it can't do like variable declarations do and complain that the version 
wasn't declared. You could even be stupid enough to declare your own version 
D_Inline_Asm_X86_65, so it's not even like the compiler can necessarily complain 
when a version declaration uses a version which is almost the same as a correct 
one but not quite (since you could just not be compiling with that version 
declared at the moment).

So, while I agree that the current situation with versions and mispelling them 
is problematic, I haven't a clue how you'd fix it right now. If _all_ versions 
had to be declared and then only the enabled ones were compiled in, _then_ we 
could make it work, since the entire list of versions would be known, but that 
would be a definite departure from how things work now and would likely make it 
very hard to do version = otherVersion; in your code like you can do now.

- Jonathan M Davis