Rollup merge of rust-lang#37430 - robinst:missing-crate-message-add-semicolon, r=eddyb

Add semicolon to "Maybe a missing `extern crate foo`" message I had it a couple of times that I was missing the "extern crate" line after I introduced a new dependency. So I copied the text from the message and inserted it into the beginning of my code, only to find the compiler complaining that I was missing the semicolon. (I forgot to add it after the text that I had pasted.) There's a similar message which does include the semicolon, namely "help: you can import it into scope: `use foo::Bar;`". I think the two messages should be consistent, so this change adds it for "extern crate".

Author: GuillaumeGomez

src/librustc_resolve/lib.rs

@@ -1401,7 +1401,7 @@ impl<'a> Resolver<'a> {
 
  format!("Did you mean `{}{}`?", prefix, path_str)
  }
- None => format!("Maybe a missing `extern crate {}`?", segment_name),
+ None => format!("Maybe a missing `extern crate {};`?", segment_name),
  }
  } else {
  format!("Could not find `{}` in `{}`", segment_name, module_name)

src/test/compile-fail/issue-12612.rs

@@ -16,7 +16,7 @@ use foo::bar;
 
 mod test {
  use bar::foo; //~ ERROR unresolved import `bar::foo` [E0432]
- //~^ Maybe a missing `extern crate bar`?
+ //~^ Maybe a missing `extern crate bar;`?
 }
 
 fn main() {}

src/test/compile-fail/issue-1697.rs

@@ -11,6 +11,6 @@
 // Testing that we don't fail abnormally after hitting the errors
 
 use unresolved::*; //~ ERROR unresolved import `unresolved::*` [E0432]
- //~^ Maybe a missing `extern crate unresolved`?
+ //~^ Maybe a missing `extern crate unresolved;`?
 
 fn main() {}

src/test/compile-fail/unresolved-import.rs

@@ -11,7 +11,7 @@
 // ignore-tidy-linelength
 
 use foo::bar; //~ ERROR unresolved import `foo::bar` [E0432]
- //~^ Maybe a missing `extern crate foo`?
+ //~^ Maybe a missing `extern crate foo;`?
 
 use bar::Baz as x; //~ ERROR unresolved import `bar::Baz` [E0432]
  //~^ no `Baz` in `bar`. Did you mean to use `Bar`?