ImportC + metaprogramming?

[max haughton]

On Monday, 17 January 2022 at 07:11:08 UTC, bauss wrote:
> On Sunday, 16 January 2022 at 08:13:37 UTC, Walter Bright wrote:
>> In this PR,
>>
>> https://github.com/dlang/druntime/pull/3670
>>
>> I added the ability for an ImportC file to import a D file. 
>> The initial purpose was so that core.stdc.stdarg could be 
>> imported to support variadics in C, without reimplementing 
>> them.
>>
>> I realized that this actually works - ImportC code can call D 
>> code! even use D templates!
>>
>> So then I got to thinking "what the hell have I unleashed?"
>>
>> I think I just destroyed dtoh.
>
> Unleashed the dragon

The dragon has no flame. If you use this how do you use (say) a 
slice? dtoh does this automatically by providing a templates 
struct, what does this do on the C side?