diff options
Diffstat (limited to 'library/std/src/keyword_docs.rs')
| -rw-r--r-- | library/std/src/keyword_docs.rs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/library/std/src/keyword_docs.rs b/library/std/src/keyword_docs.rs index 91701576130..c9595b051e2 100644 --- a/library/std/src/keyword_docs.rs +++ b/library/std/src/keyword_docs.rs @@ -388,11 +388,15 @@ mod enum_keyword {} /// lazy_static;`. The other use is in foreign function interfaces (FFI). /// /// `extern` is used in two different contexts within FFI. The first is in the form of external -/// blocks, for declaring function interfaces that Rust code can call foreign code by. +/// blocks, for declaring function interfaces that Rust code can call foreign code by. This use +/// of `extern` is unsafe, since we are asserting to the compiler that all function declarations +/// are correct. If they are not, using these items may lead to undefined behavior. /// /// ```rust ignore +/// // SAFETY: The function declarations given below are in +/// // line with the header files of `my_c_library`. /// #[link(name = "my_c_library")] -/// extern "C" { +/// unsafe extern "C" { /// fn my_c_function(x: i32) -> bool; /// } /// ``` |