Bug 23812 – ImportC: allow adding function attributes to imported C functions

C functions imported with ImportC currently don't get any function attributes, so they're currently not callable in `nothrow` `@nogc` `pure` `@safe` contexts. nothrow and @nogc could be given by default, the only exceptions would be if the imported function has a callback, or if it is actually implemented in D but imported through a C file for some reason. @safe is rarer for C functions since they often receive raw pointers, so we might just require use of `@trusted` when calling them from a `@safe` context. pure is also rarer for C, since C libraries often use global variables / stderr for error reporting, but ImportC could recognize the `__attribute__((pure))` extension some compilers have. In any case, new syntax could be created along the lines of: ```C #pragma nogc nothrow #include <somelibrary.h> ```

Yes, I had to remove the nogc and nothrow attributes from my project to get it compiling with importc usage. I think the defaults have to be as is since we don’t have negation of pure nogc nothrow. But I agree that a pragma would suffice.

I've translated a fair share of C and AFAIK they all could be `nothrow @nogc`.

@tim-dlang created dlang/dmd pull request #16820 "Fix bugzilla 23812 - ImportC: allow adding function attributes to imp…" fixing this issue: - Fix bugzilla 23812 - ImportC: allow adding function attributes to imported C functions This adds a new pragma for ImportC, which allows to set default storage classes. Only `nothrow`, `@nogc` and `pure` are supported for now. They can be disabled later with the same pragma using a minus. Unknown pragmas are ignored. The pragma starts with identifier `D` to avoid conflicts. https://github.com/dlang/dmd/pull/16820

dlang/dmd pull request #16820 "Fix bugzilla 23812 - ImportC: allow adding function attributes to imp…" was merged into master: - d956dc0ccc458a8506a2776ebc1eb00ef5127685 by Tim Schendekehl: Fix bugzilla 23812 - ImportC: allow adding function attributes to imported C functions This adds a new pragma for ImportC, which allows to set default storage classes. Only `nothrow`, `@nogc` and `pure` are supported for now. They can be disabled later using `#pragma attribute(pop)`. Unknown storage classes are ignored. https://github.com/dlang/dmd/pull/16820