review comment

Author: estebank

src/libsyntax/parse/diagnostics.rs

@@ -800,7 +800,7 @@ impl<'a> Parser<'a> {
                         .span_label(
                             extern_sp,
                             "`extern` blocks define existing foreign functions and `fn`s \
-                             inside of them can't have a body")
+                             inside of them cannot have a body")
                         .help("you might have meant to write a function accessible through ffi, \
                                which can be done by writing `extern fn` outside of the \
                                `extern` block")

src/test/ui/extern/extern-ffi-fn-with-body.stderr

@@ -2,7 +2,7 @@ error: incorrect `fn` inside `extern` block
   --> $DIR/extern-ffi-fn-with-body.rs:2:8
    |
 LL |   extern "C" {
-   |   ------ `extern` blocks define existing foreign functions and `fn`s inside of them can't have a body
+   |   ------ `extern` blocks define existing foreign functions and `fn`s inside of them cannot have a body
 LL |       fn foo() -> i32 {
    |  ________^^^__________-
    | |        |