Document "prevent unwinding into FFI"

diwic · web-flow · commit 512d377f32fc · 2018-01-12T13:41:51.000+01:00
As suggested in rust-lang/rust#46833
diff --git a/src/items/functions.md b/src/items/functions.md
@@ -165,3 +165,4 @@ same type as the functions declared in an extern block.
 let fptr: extern "C" fn() -> i32 = new_i32;
 ```
 
+As non-Rust calling conventions do not support unwinding, unwinding past the end of an extern function will cause the process to abort (in LLVM, this is implemented by executing an illegal instruction).

Original file line number	Diff line number	Diff line change
`@@ -165,3 +165,4 @@ same type as the functions declared in an extern block.`
`165`	`165`	`let fptr: extern "C" fn() -> i32 = new_i32;`
`166`	`166`	```
`167`	`167`
	`168`	`+As non-Rust calling conventions do not support unwinding, unwinding past the end of an extern function will cause the process to abort (in LLVM, this is implemented by executing an illegal instruction).`