On Saturday, August 17, 2024 10:43:34 PM MDT Manu via Digitalmars-d wrote:
> I just tried using ImportC for the first time ever, but I was surprised
> when I immediately received a sea of errors calling the C symbols from
> `nothrow @nogc` functions.
> My entire program is `nothrow @nogc`... I assumed ImportC would be
> supremely suitable in this context, but apparently not...
>
> Is there something I've missed? Is there a plan for this?
> I found just one single very short forum thread...
>
> This is classic D experience; so much work has been done on this, and then the moment I try and use something I encounter a showstopping oversight >_<

As I understand it, the core problem is that the linkage of the function does not necessarily match how the function is implemented. So, for instance, you could have an extern(C) function written in D which happily uses the GC and/or exceptions. Obviously, in most cases, this is not true - particularly when you're using importC, since the only way that such C code would use D features is if it calls D code somewhere, which is only going to happen under pretty specialized circumstances - so in most cases, you probably would prefer that extern(C) functions be treated as nothrow and @nogc. This is far less of an issue when not using importC, because then you can just slap @nogc and nothrow on the bindings that you write (druntime routinely does this to entire files with the OS bindings), but for importC, you're not writing the bindings.

I don't know if there's any plan on how to deal with this. However, importC is fairly new and is a feature that has grown quite organically (and weirdly, Walter considers it to be a compiler feature and not a language feature), so it wouldn't be surprising if this behavior were changed upon request or that some way were provided to force it (though since Walter wants imports for importC to look identical to normal D imports, I don't know how we'd force it without forcing it globally). On the whole, importC has grown features in response to issues that have come up rather than having be fully planned out from the get-go (and a number of the issues that have come up seem to be ones that Walter didn't foresee).

So, I'd suggest that you open an enhancement request and tag it as being importC, since Walter tends to give those kinds of issue priority (and having brought up the issue here like you have may bring it to his attention). I don't know what his response to the issue will be, but the current state of things is obviously less than ideal.

- Jonathan M Davis