Add GenericParam, refactor Generics in ast, hir, rustdoc

The Generics now contain one Vec of an enum for the generic parameters,
rather than two separate Vec's for lifetime and type parameters.

Additionally, places that previously used Vec<LifetimeDef> now use
Vec<GenericParam> instead.

src/librustc/hir/intravisit.rs

@@ -279,6 +279,9 @@ pub trait Visitor<'v> : Sized {
     fn visit_ty(&mut self, t: &'v Ty) {
         walk_ty(self, t)
     }
+    fn visit_generic_param(&mut self, p: &'v GenericParam) {
+        walk_generic_param(self, p)
+    }
     fn visit_generics(&mut self, g: &'v Generics) {
         walk_generics(self, g)
     }
@@ -336,9 +339,6 @@ pub trait Visitor<'v> : Sized {
     fn visit_lifetime(&mut self, lifetime: &'v Lifetime) {
         walk_lifetime(self, lifetime)
     }
-    fn visit_lifetime_def(&mut self, lifetime: &'v LifetimeDef) {
-        walk_lifetime_def(self, lifetime)
-    }
     fn visit_qpath(&mut self, qpath: &'v QPath, id: NodeId, span: Span) {
         walk_qpath(self, qpath, id, span)
     }
@@ -430,17 +430,12 @@ pub fn walk_lifetime<'v, V: Visitor<'v>>(visitor: &mut V, lifetime: &'v Lifetime
     }
 }
 
-pub fn walk_lifetime_def<'v, V: Visitor<'v>>(visitor: &mut V, lifetime_def: &'v LifetimeDef) {
-    visitor.visit_lifetime(&lifetime_def.lifetime);
-    walk_list!(visitor, visit_lifetime, &lifetime_def.bounds);
-}
-
 pub fn walk_poly_trait_ref<'v, V>(visitor: &mut V,
                                   trait_ref: &'v PolyTraitRef,
                                   _modifier: TraitBoundModifier)
     where V: Visitor<'v>
 {
-    walk_list!(visitor, visit_lifetime_def, &trait_ref.bound_lifetimes);
+    walk_list!(visitor, visit_generic_param, &trait_ref.bound_generic_params);
     visitor.visit_trait_ref(&trait_ref.trait_ref);
 }
 
@@ -581,7 +576,7 @@ pub fn walk_ty<'v, V: Visitor<'v>>(visitor: &mut V, typ: &'v Ty) {
         }
         TyBareFn(ref function_declaration) => {
             visitor.visit_fn_decl(&function_declaration.decl);
-            walk_list!(visitor, visit_lifetime_def, &function_declaration.lifetimes);
+            walk_list!(visitor, visit_generic_param, &function_declaration.generic_params);
         }
         TyPath(ref qpath) => {
             visitor.visit_qpath(qpath, typ.id, typ.span);
@@ -729,14 +724,23 @@ pub fn walk_ty_param_bound<'v, V: Visitor<'v>>(visitor: &mut V, bound: &'v TyPar
     }
 }
 
-pub fn walk_generics<'v, V: Visitor<'v>>(visitor: &mut V, generics: &'v Generics) {
-    for param in &generics.ty_params {
-        visitor.visit_id(param.id);
-        visitor.visit_name(param.span, param.name);
-        walk_list!(visitor, visit_ty_param_bound, &param.bounds);
-        walk_list!(visitor, visit_ty, &param.default);
+pub fn walk_generic_param<'v, V: Visitor<'v>>(visitor: &mut V, param: &'v GenericParam) {
+    match *param {
+        GenericParam::Lifetime(ref ld) => {
+            visitor.visit_lifetime(&ld.lifetime);
+            walk_list!(visitor, visit_lifetime, &ld.bounds);
+        }
+        GenericParam::Type(ref ty_param) => {
+            visitor.visit_id(ty_param.id);
+            visitor.visit_name(ty_param.span, ty_param.name);
+            walk_list!(visitor, visit_ty_param_bound, &ty_param.bounds);
+            walk_list!(visitor, visit_ty, &ty_param.default);
+        }
     }
-    walk_list!(visitor, visit_lifetime_def, &generics.lifetimes);
+}
+
+pub fn walk_generics<'v, V: Visitor<'v>>(visitor: &mut V, generics: &'v Generics) {
+    walk_list!(visitor, visit_generic_param, &generics.params);
     visitor.visit_id(generics.where_clause.id);
     walk_list!(visitor, visit_where_predicate, &generics.where_clause.predicates);
 }
@@ -748,11 +752,11 @@ pub fn walk_where_predicate<'v, V: Visitor<'v>>(
     match predicate {
         &WherePredicate::BoundPredicate(WhereBoundPredicate{ref bounded_ty,
                                                             ref bounds,
-                                                            ref bound_lifetimes,
+                                                            ref bound_generic_params,
                                                             ..}) => {
             visitor.visit_ty(bounded_ty);
             walk_list!(visitor, visit_ty_param_bound, bounds);
-            walk_list!(visitor, visit_lifetime_def, bound_lifetimes);
+            walk_list!(visitor, visit_generic_param, bound_generic_params);
         }
         &WherePredicate::RegionPredicate(WhereRegionPredicate{ref lifetime,
                                                               ref bounds,