DLF September 2023 Monthly Meeting Summary

[Tim]

On Sunday, 12 November 2023 at 21:55:31 UTC, Paul Backus wrote:
> Personally, my number-one complaint with dmd-as-a-library is 
> that I am forced to use `extern(C++)` when creating my own 
> `Visitor` classes.
>
> In [`dmdtags`][1], this requirement has made it necessary for 
> me to implement my own C++-compatible [`Span`][2] and 
> [`Appender`][3] types, just to avoid the C++ mangling errors 
> caused by D's built-in `T[]` slices.
>
> I have no use for overriding AST nodes, but the ability to use 
> `extern(D)` visitors with dmd-as-a-library would be a welcome 
> improvement.

The visitor can already be `extern(D)`. Only member functions 
overriding those in the base class need to be `extern(C++)`. 
Other member functions can then use paratemers, which would be 
incompatible with `extern(C++)`.