Implicit nothrow with -betterC

[Manuel Maier]

I've been experimenting with the -betterC switch and stumbled 
upon something that didn't quite make sense to me.

I've put together a small example [1] of Win32 code with a window 
callback that has to be nothrow as per the definition of WNDPROC 
somewhere in core.sys.windows. However, calling anything from 
within the window callback not marked as nothrow will result in a 
compile error. This behavior is expected for regular D code and 
there are many ways to fix the code so the compiler no longer 
emits the error. What bugs me is the following.

According to the docs, exceptions "won't work":

 From https://dlang.org/spec/betterc.html#consequences
> As no Druntime is available, many D features won't work. For 
> example:
> [...]
>     7. Exceptions
> [...]

To me, this means it should be impossible to write -betterC code 
that throws exceptions. So shouldn't -betterC imply nothrow on 
all functions by default? Is this a compiler bug? If not, in what 
way is the explicit nothrow attribute still useful for -betterC?


[1] 
https://gist.github.com/Manuzor/81cc01d57543202d68eab5a84d944027