remove error code description

src/librustc/diagnostics.rs

@@ -1351,74 +1351,6 @@ struct Foo<T: 'static> {
 ```
 "##,
 
-E0312: r##"
-A lifetime of reference outlives lifetime of borrowed content.
-
-Erroneous code example:
-
-```compile_fail,E0312
-fn make_child<'tree, 'human>(
-  x: &'human i32,
-  y: &'tree i32
-) -> &'human i32 {
-    if x > y
-       { x }
-    else
-       { y }
-       // error: lifetime of reference outlives lifetime of borrowed content
-}
-```
-
-The function declares that it returns a reference with the `'human`
-lifetime, but it may return data with the `'tree` lifetime. As neither
-lifetime is declared longer than the other, this results in an
-error. Sometimes, this error is because the function *body* is
-incorrect -- that is, maybe you did not *mean* to return data from
-`y`. In that case, you should fix the function body.
-
-Often, however, the body is correct. In that case, the function
-signature needs to be altered to match the body, so that the caller
-understands that data from either `x` or `y` may be returned. The
-simplest way to do this is to give both function parameters the *same*
-named lifetime:
-
-```
-fn make_child<'human>(
-  x: &'human i32,
-  y: &'human i32
-) -> &'human i32 {
-    if x > y
-       { x }
-    else
-       { y } // ok!
-}
-```
-
-However, in some cases, you may prefer to explicitly declare that one lifetime
-outlives another using a `where` clause:
-
-```
-fn make_child<'tree, 'human>(
-  x: &'human i32,
-  y: &'tree i32
-) -> &'human i32
-where
-  'tree: 'human
-{
-    if x > y
-       { x }
-    else
-       { y } // ok!
-}
-```
-
-Here, the where clause `'tree: 'human` can be read as "the lifetime
-'tree outlives the lifetime 'human" -- meaning, references with the
-`'tree` lifetime live *at least as long as* references with the
-`'human` lifetime. Therefore, it is safe to return data with lifetime
-`'tree` when data with the lifetime `'human` is needed.
-"##,
-
 E0317: r##"
 This error occurs when an `if` expression without an `else` block is used in a
 context where a type other than `()` is expected, for example a `let`
@@ -2028,6 +1960,7 @@ register_diagnostics! {
 //  E0304, // expected signed integer constant
 //  E0305, // expected constant
     E0311, // thing may not live long enough
+    E0312, // lifetime of reference outlives lifetime of borrowed content
     E0313, // lifetime of borrowed pointer outlives lifetime of captured variable
     E0314, // closure outlives stack frame
     E0315, // cannot invoke closure outside of its lifetime