Sometimes, a C library wants to provide a pointer to something, but not let you
know the internal details of the thing it wants. The simplest way is to use a
`void *` argument:
Sometimes, a C library wants to provide a pointer to something, but not let you know the internal details of the thing it wants.
A stable and simple way is to use a `void *` argument:
```c
void foo(void *arg);
@ -774,3 +773,9 @@ Notice that it is a really bad idea to use an empty enum as FFI type.
The compiler relies on empty enums being uninhabited, so handling values of type
`&Empty` is a huge footgun and can lead to buggy program behavior (by triggering
undefined behavior).
> **NOTE:** The simplest way would use "extern types".
But it's currently (as of June 2021) unstable and has some unresolved questions, see the [RFC page][extern-type-rfc] and the [tracking issue][extern-type-issue] for more details.
Eric Huss
3 years ago
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GitHub