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Rollup merge of #22295 - steveklabnik:gh9980, r=alexcrichton

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Fixes #9980
This commit is contained in:
Manish Goregaokar 2015-02-15 18:30:35 +05:30
commit 0f66e314db
1 changed files with 11 additions and 4 deletions
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15
src/doc/trpl/ffi.md
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@ -420,7 +420,7 @@ fn main() {
```
Alternatively, you may need to alter global state provided by a foreign
interface. To do this, statics can be declared with `mut` so rust can mutate
interface. To do this, statics can be declared with `mut` so we can mutate
them.
```no_run
@ -436,12 +436,19 @@ extern {
fn main() {
let prompt = CString::from_slice(b"[my-awesome-shell] $");
unsafe { rl_prompt = prompt.as_ptr(); }
// get a line, process it
unsafe { rl_prompt = ptr::null(); }
unsafe {
rl_prompt = prompt.as_ptr();
println!("{}", rl_prompt);
rl_prompt = ptr::null();
}
}
```
Note that all interaction with a `static mut` is unsafe, both reading and
writing. Dealing with global mutable state requires a great deal of care.
# Foreign calling conventions
Most foreign code exposes a C ABI, and Rust uses the platform's C calling convention by default when