Remove hir::Label.

It's identical to `ast::Label`.

src/librustc/hir/mod.rs

@@ -19,7 +19,7 @@ use syntax_pos::{Span, DUMMY_SP, symbol::InternedString};
 use syntax::source_map::{self, Spanned};
 use rustc_target::spec::abi::Abi;
 use syntax::ast::{self, CrateSugar, Ident, Name, NodeId, DUMMY_NODE_ID, AsmDialect};
-use syntax::ast::{Attribute, Lit, StrStyle, FloatTy, IntTy, UintTy};
+use syntax::ast::{Attribute, Label, Lit, StrStyle, FloatTy, IntTy, UintTy};
 use syntax::attr::InlineAttr;
 use syntax::ext::hygiene::SyntaxContext;
 use syntax::ptr::P;
@@ -142,17 +142,6 @@ pub const DUMMY_HIR_ID: HirId = HirId {
 
 pub const DUMMY_ITEM_LOCAL_ID: ItemLocalId = ItemLocalId::MAX;
 
-#[derive(Clone, RustcEncodable, RustcDecodable, Copy)]
-pub struct Label {
-    pub ident: Ident,
-}
-
-impl fmt::Debug for Label {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "label({:?})", self.ident)
-    }
-}
-
 #[derive(Clone, RustcEncodable, RustcDecodable, Copy)]
 pub struct Lifetime {
     pub id: NodeId,

src/librustc/ich/impls_hir.rs

@@ -153,7 +153,7 @@ impl_stable_hash_for!(enum hir::LifetimeName {
     Error,
 });
 
-impl_stable_hash_for!(struct hir::Label {
+impl_stable_hash_for!(struct ast::Label {
     ident
 });