Temporary bootstrapping hack: introduce syntax for r egion bounds like 'b:'a,

meaning `'b outlives 'a`. Syntax currently does nothing but is needed for full
fix to #5763. To use this syntax, the issue_5763_bootstrap feature guard is
required.

src/libsyntax/ast.rs

@@ -160,6 +160,12 @@ pub struct Lifetime {
     pub name: Name
 }
 
+#[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash, Show)]
+pub struct LifetimeDef {
+    pub lifetime: Lifetime,
+    pub bounds: Vec<Lifetime>
+}
+
 /// A "Path" is essentially Rust's notion of a name; for instance:
 /// std::cmp::PartialEq  .  It's represented as a sequence of identifiers,
 /// along with a bunch of supporting information.
@@ -231,7 +237,7 @@ pub struct TyParam {
 /// of a function, enum, trait, etc.
 #[deriving(Clone, PartialEq, Eq, Encodable, Decodable, Hash, Show)]
 pub struct Generics {
-    pub lifetimes: Vec<Lifetime>,
+    pub lifetimes: Vec<LifetimeDef>,
     pub ty_params: OwnedSlice<TyParam>,
 }
 
@@ -861,7 +867,7 @@ impl fmt::Show for Onceness {
 /// Represents the type of a closure
 #[deriving(PartialEq, Eq, Encodable, Decodable, Hash, Show)]
 pub struct ClosureTy {
-    pub lifetimes: Vec<Lifetime>,
+    pub lifetimes: Vec<LifetimeDef>,
     pub fn_style: FnStyle,
     pub onceness: Onceness,
     pub decl: P<FnDecl>,
@@ -876,7 +882,7 @@ pub struct ClosureTy {
 pub struct BareFnTy {
     pub fn_style: FnStyle,
     pub abi: Abi,
-    pub lifetimes: Vec<Lifetime>,
+    pub lifetimes: Vec<LifetimeDef>,
     pub decl: P<FnDecl>
 }