Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/src/doc/book/redirects/ffi.md b/src/doc/book/redirects/ffi.md
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+% FFI
+
+<small>There is a new edition of the book and this is an old link.</small>
+
+> Sometimes, your Rust code may need to interact with code written in another language.
+> To do this, Rust has a keyword, `extern`, that facilitates creating and using a _Foreign Function Interface_ (FFI).
+
+```rust
+extern "C" {
+    fn abs(input: i32) -> i32;
+}
+
+fn main() {
+    unsafe {
+        println!("Absolute value of -3 according to C: {}", abs(-3));
+    }
+}
+```
+
+---
+
+You can find the latest version of this information
+[here](ch19-01-unsafe-rust.html#using-extern-functions-to-call-external-code)
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