Update diagnostics.rs

Author: GuillaumeGomez

src/librustc/diagnostics.rs

@@ -278,10 +278,12 @@ enum Method {
 
 you would match it using:
 
+```
 match m {
     Method::GET => ...
     Method::POST => ...
 }
+```
 
 If you don't qualify the names, the code will bind new variables named "GET" and
 "POST" instead. This behavior is likely not what you want, so rustc warns when
@@ -290,8 +292,10 @@ that happens.
 Qualified names are good practice, and most code works well with them. But if
 you prefer them unqualified, you can import the variants into scope:
 
-    use Method::*;
-    enum Method { GET, POST }
+```
+use Method::*;
+enum Method { GET, POST }
+```
 "##,
 
 E0267: r##"
@@ -311,7 +315,9 @@ E0296: r##"
 This error indicates that the given recursion limit could not be parsed. Ensure
 that the value provided is a positive integer between quotes, like so:
 
-    #![recursion_limit="1000"]
+```
+#![recursion_limit="1000"]
+```
 "##,
 
 E0297: r##"
@@ -320,25 +326,27 @@ that a name will be extracted in all cases. Instead of pattern matching the
 loop variable, consider using a `match` or `if let` inside the loop body. For
 instance:
 
-    // This fails because `None` is not covered.
-    for Some(x) in xs {
-        ...
-    }
-    
-    // Match inside the loop instead:
-    for item in xs {
-        match item {
-            Some(x) => ...
-            None => ...
-        }
+```
+// This fails because `None` is not covered.
+for Some(x) in xs {
+    ...
+}
+
+// Match inside the loop instead:
+for item in xs {
+    match item {
+        Some(x) => ...
+        None => ...
     }
-    
-    // Or use `if let`:
-    for item in xs {
-        if let Some(x) = item {
-            ...
-        }
+}
+
+// Or use `if let`:
+for item in xs {
+    if let Some(x) = item {
+        ...
     }
+}
+```
 "##,
 
 E0301: r##"
@@ -348,11 +356,13 @@ on which the match depends in such a way, that the match would not be
 exhaustive. For instance, the following would not match any arm if mutable
 borrows were allowed:
 
-    match Some(()) {
-        None => { },
-        option if option.take().is_none() => { /* impossible, option is `Some` */ },
-        Some(_) => { } // When the previous match failed, the option became `None`.
-    }
+```
+match Some(()) {
+    None => { },
+    option if option.take().is_none() => { /* impossible, option is `Some` */ },
+    Some(_) => { } // When the previous match failed, the option became `None`.
+}
+```
 "##,
 
 E0302: r##"
@@ -362,32 +372,36 @@ on which the match depends in such a way, that the match would not be
 exhaustive. For instance, the following would not match any arm if assignments
 were allowed:
 
-    match Some(()) {
-        None => { },
-        option if { option = None; false } { },
-        Some(_) => { } // When the previous match failed, the option became `None`.
-    }
+```
+match Some(()) {
+    None => { },
+    option if { option = None; false } { },
+    Some(_) => { } // When the previous match failed, the option became `None`.
+}
+```
 "##,
 
 E0303: r##"
 In certain cases it is possible for sub-bindings to violate memory safety.
 Updates to the borrow checker in a future version of Rust may remove this
 restriction, but for now patterns must be rewritten without sub-bindings.
 
-    // Code like this...
-    match Some(5) {
-        ref op_num @ Some(num) => ...
-        None => ...
-    }
-    
-    // After.
-    match Some("hi".to_string()) {
-        Some(ref s) => {
-            let op_string_ref = &Some(&s);
-            ...
-        }
-        None => ...
+```
+// Code like this...
+match Some(5) {
+    ref op_num @ Some(num) => ...
+    None => ...
+}
+
+// After.
+match Some("hi".to_string()) {
+    Some(ref s) => {
+        let op_string_ref = &Some(&s);
+        ...
     }
+    None => ...
+}
+```
 
 The `op_string_ref` binding has type &Option<&String> in both cases.