Type safety could prevent nuclear war

[tsbockman via Digitalmars-d]

On Thursday, 4 February 2016 at 23:59:06 UTC, H. S. Teoh wrote:
> On Thu, Feb 04, 2016 at 11:47:53PM +0000, tsbockman via 
> Digitalmars-d wrote: [...]
>> Even so, I think that qualifies as a compiler bug or a hole in 
>> the D spec.
>
> Nah... while D, by default, tries to be type-safe and prevent 
> guffaws like the above, it *is* also a systems programming 
> language (or at least, that's one of the stated goals), so it 
> does allow you to go under the hood to do things that you 
> normally aren't allowed to do.
>
> Linking to foreign languages is a use case for allowing 
> extern(C) function names: if you know the mangling scheme of 
> the target language, you can declare the mangled name under 
> extern(C) and that will allow D code to call functions written 
> in the target language directly. Otherwise you'd have to change 
> the compiler (and wait for the next release, etc.) before you 
> could do that.
>
>
> T

I'm not saying that `extern(C)` is bad in general; I understand 
why it's necessary.

I'm saying that anonymous' example 
(http://forum.dlang.org/post/n90ngu$1r6v$1@digitalmars.com) 
showcases a hole in the spec, because in it the D compiler has 
access to the full source code of the function being linked to, 
and doesn't bother to verify that its signature in main.d is 
compatible with the definition in deref.d.

If the D compiler does *not* have access to the function's 
definition, then obviously it cannot perform this verification.