Remove LoopIdResult

It's redundant as Result already implements Encodable
as well as Decodable.

src/librustc/cfg/construct.rs

@@ -582,7 +582,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                   scope_cf_kind: ScopeCfKind) -> (region::Scope, CFGIndex) {
 
         match destination.target_id {
-            hir::LoopIdResult::Ok(loop_id) => {
+            Ok(loop_id) => {
                 for b in &self.breakable_block_scopes {
                     if b.block_expr_id == self.tcx.hir.node_to_hir_id(loop_id).local_id {
                         let scope_id = self.tcx.hir.node_to_hir_id(loop_id).local_id;
@@ -603,7 +603,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                 }
                 span_bug!(expr.span, "no scope for id {}", loop_id);
             }
-            hir::LoopIdResult::Err(err) => span_bug!(expr.span, "scope error: {}",  err),
+            Err(err) => span_bug!(expr.span, "scope error: {}",  err),
         }
     }
 }

src/librustc/hir/intravisit.rs

@@ -1039,9 +1039,8 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
             if let Some(ref label) = destination.label {
                 visitor.visit_label(label);
                 match destination.target_id {
-                    LoopIdResult::Ok(node_id) =>
+                    Ok(node_id) => visitor.visit_def_mention(Def::Label(node_id)),
-                        visitor.visit_def_mention(Def::Label(node_id)),
+                    Err(_) => {},
-                    LoopIdResult::Err(_) => {},
                 };
             }
             walk_list!(visitor, visit_expr, opt_expr);
@@ -1050,9 +1049,8 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
             if let Some(ref label) = destination.label {
                 visitor.visit_label(label);
                 match destination.target_id {
-                    LoopIdResult::Ok(node_id) =>
+                    Ok(node_id) => visitor.visit_def_mention(Def::Label(node_id)),
-                        visitor.visit_def_mention(Def::Label(node_id)),
+                    Err(_) => {},
-                    LoopIdResult::Err(_) => {},
                 };
             }
         }

src/librustc/hir/lowering.rs

@@ -929,9 +929,9 @@ impl<'a> LoweringContext<'a> {
         match destination {
             Some((id, label)) => {
                 let target_id = if let Def::Label(loop_id) = self.expect_full_def(id) {
-                    hir::LoopIdResult::Ok(self.lower_node_id(loop_id).node_id)
+                    Ok(self.lower_node_id(loop_id).node_id)
                 } else {
-                    hir::LoopIdResult::Err(hir::LoopIdError::UnresolvedLabel)
+                    Err(hir::LoopIdError::UnresolvedLabel)
                 };
                 hir::Destination {
                     label: self.lower_label(Some(label)),
@@ -3598,7 +3598,7 @@ impl<'a> LoweringContext<'a> {
                             hir::ExprBreak(
                                 hir::Destination {
                                     label: None,
-                                    target_id: hir::LoopIdResult::Ok(catch_node),
+                                    target_id: Ok(catch_node),
                                 },
                                 Some(from_err_expr),
                             ),

src/librustc/hir/mod.rs

@@ -1502,39 +1502,6 @@ impl fmt::Display for LoopIdError {
     }
 }
 
-// FIXME(cramertj) this should use `Result` once master compiles w/ a vesion of Rust where
-// `Result` implements `Encodable`/`Decodable`
-#[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
-pub enum LoopIdResult {
-    Ok(NodeId),
-    Err(LoopIdError),
-}
-impl Into<Result<NodeId, LoopIdError>> for LoopIdResult {
-    fn into(self) -> Result<NodeId, LoopIdError> {
-        match self {
-            LoopIdResult::Ok(ok) => Ok(ok),
-            LoopIdResult::Err(err) => Err(err),
-        }
-    }
-}
-impl From<Result<NodeId, LoopIdError>> for LoopIdResult {
-    fn from(res: Result<NodeId, LoopIdError>) -> Self {
-        match res {
-            Ok(ok) => LoopIdResult::Ok(ok),
-            Err(err) => LoopIdResult::Err(err),
-        }
-    }
-}
-
-impl LoopIdResult {
-    pub fn ok(self) -> Option<NodeId> {
-        match self {
-            LoopIdResult::Ok(node_id) => Some(node_id),
-            LoopIdResult::Err(_) => None,
-        }
-    }
-}
-
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]
 pub struct Destination {
     // This is `Some(_)` iff there is an explicit user-specified `label
@@ -1542,7 +1509,7 @@ pub struct Destination {
 
     // These errors are caught and then reported during the diagnostics pass in
     // librustc_passes/loops.rs
-    pub target_id: LoopIdResult,
+    pub target_id: Result<NodeId, LoopIdError>,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug, Copy)]

src/librustc/ich/impls_hir.rs

@@ -656,11 +656,6 @@ impl_stable_hash_for!(struct hir::Destination {
 
 impl_stable_hash_for_spanned!(ast::Ident);
 
-impl_stable_hash_for!(enum hir::LoopIdResult {
-    Ok(node_id),
-    Err(loop_id_error)
-});
-
 impl_stable_hash_for!(enum hir::LoopIdError {
     OutsideLoopScope,
     UnlabeledCfInWhileCondition,

src/librustc/middle/liveness.rs

@@ -1051,9 +1051,8 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
           hir::ExprBreak(label, ref opt_expr) => {
               // Find which label this break jumps to
               let target = match label.target_id {
-                    hir::LoopIdResult::Ok(node_id) => self.break_ln.get(&node_id),
+                    Ok(node_id) => self.break_ln.get(&node_id),
-                    hir::LoopIdResult::Err(err) =>
+                    Err(err) => span_bug!(expr.span, "loop scope error: {}", err),
-                        span_bug!(expr.span, "loop scope error: {}", err),
               }.map(|x| *x);
 
               // Now that we know the label we're going to,
@@ -1068,9 +1067,8 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
           hir::ExprAgain(label) => {
               // Find which label this expr continues to
               let sc = match label.target_id {
-                    hir::LoopIdResult::Ok(node_id) => node_id,
+                    Ok(node_id) => node_id,
-                    hir::LoopIdResult::Err(err) =>
+                    Err(err) => span_bug!(expr.span, "loop scope error: {}", err),
-                        span_bug!(expr.span, "loop scope error: {}", err),
               };
 
               // Now that we know the label we're going to,

src/librustc_mir/hair/cx/expr.rs

@@ -536,21 +536,19 @@ fn make_mirror_unadjusted<'a, 'gcx, 'tcx>(cx: &mut Cx<'a, 'gcx, 'tcx>,
         hir::ExprRet(ref v) => ExprKind::Return { value: v.to_ref() },
         hir::ExprBreak(dest, ref value) => {
             match dest.target_id {
-                hir::LoopIdResult::Ok(target_id) => ExprKind::Break {
+                Ok(target_id) => ExprKind::Break {
                     label: region::Scope::Node(cx.tcx.hir.node_to_hir_id(target_id).local_id),
                     value: value.to_ref(),
                 },
-                hir::LoopIdResult::Err(err) =>
+                Err(err) => bug!("invalid loop id for break: {}", err)
-                    bug!("invalid loop id for break: {}", err)
             }
         }
         hir::ExprAgain(dest) => {
             match dest.target_id {
-                hir::LoopIdResult::Ok(loop_id) => ExprKind::Continue {
+                Ok(loop_id) => ExprKind::Continue {
                     label: region::Scope::Node(cx.tcx.hir.node_to_hir_id(loop_id).local_id),
                 },
-                hir::LoopIdResult::Err(err) =>
+                Err(err) => bug!("invalid loop id for continue: {}", err)
-                    bug!("invalid loop id for continue: {}", err)
             }
         }
         hir::ExprMatch(ref discr, ref arms, _) => {

src/librustc_passes/loops.rs

@@ -133,8 +133,7 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
                 self.require_loop("break", e.span);
             }
             hir::ExprAgain(label) => {
-                if let hir::LoopIdResult::Err(
+                if let Err(hir::LoopIdError::UnlabeledCfInWhileCondition) = label.target_id {
-                        hir::LoopIdError::UnlabeledCfInWhileCondition) = label.target_id {
                     self.emit_unlabled_cf_in_while_condition(e.span, "continue");
                 }
                 self.require_loop("continue", e.span)