librustc: Forbid `..` in range patterns.

This breaks code that looks like:

    match foo {
        1..3 => { ... }
    }

Instead, write:

    match foo {
        1...3 => { ... }
    }

Closes #17295.

[breaking-change]

2 files changed, 5 insertions, 5 deletions

diff --git a/src/doc/guide.md b/src/doc/guide.md
index 0474e5a31ce..074dfc17b0d 100644
--- a/src/doc/guide.md
+++ b/src/doc/guide.md
@@ -3757,27 +3757,27 @@ match x {
 }
 ```
 
-You can match a range of values with `..`:
+You can match a range of values with `...`:
 
 ```{rust}
 let x = 1i;
 
 match x {
-    1 .. 5 => println!("one through five"),
+    1 ... 5 => println!("one through five"),
     _ => println!("anything"),
 }
 ```
 
 Ranges are mostly used with integers and single characters.
 
-If you're matching multiple things, via a `|` or a `..`, you can bind
+If you're matching multiple things, via a `|` or a `...`, you can bind
 the value to a name with `@`:
 
 ```{rust}
 let x = 1i;
 
 match x {
-    x @ 1 .. 5 => println!("got {}", x),
+    x @ 1 ... 5 => println!("got {}", x),
     _ => println!("anything"),
 }
 ```
diff --git a/src/doc/reference.md b/src/doc/reference.md
index 21da810a300..8fa282c2a39 100644
--- a/src/doc/reference.md
+++ b/src/doc/reference.md
@@ -3408,7 +3408,7 @@ may be specified with `..`. For example:
 
 let message = match x {
   0 | 1  => "not many",
-  2 .. 9 => "a few",
+  2 ... 9 => "a few",
   _      => "lots"
 };
 ```