rustc: always keep hir::Path behind a P<...>.

Author: eddyb

src/librustc/hir/lowering.rs

@@ -2725,7 +2725,7 @@ impl<'a> LoweringContext<'a> {
 
         // ::std::future::Future<future_params>
         let future_path =
-            self.std_path(span, &[sym::future, sym::Future], Some(future_params), false);
+            P(self.std_path(span, &[sym::future, sym::Future], Some(future_params), false));
 
         hir::GenericBound::Trait(
             hir::PolyTraitRef {
@@ -3094,7 +3094,7 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_trait_ref(&mut self, p: &TraitRef, itctx: ImplTraitContext<'_>) -> hir::TraitRef {
         let path = match self.lower_qpath(p.ref_id, &None, &p.path, ParamMode::Explicit, itctx) {
-            hir::QPath::Resolved(None, path) => path.and_then(|path| path),
+            hir::QPath::Resolved(None, path) => path,
             qpath => bug!("lower_trait_ref: unexpected QPath `{:?}`", qpath),
         };
         hir::TraitRef {
@@ -5577,7 +5577,7 @@ impl<'a> LoweringContext<'a> {
                         let principal = hir::PolyTraitRef {
                             bound_generic_params: hir::HirVec::new(),
                             trait_ref: hir::TraitRef {
-                                path: path.and_then(|path| path),
+                                path,
                                 hir_ref_id: hir_id,
                             },
                             span,

src/librustc/hir/mod.rs

@@ -2217,7 +2217,7 @@ pub enum UseKind {
 /// within the resolution map.
 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 pub struct TraitRef {
-    pub path: Path,
+    pub path: P<Path>,
     // Don't hash the ref_id. It is tracked via the thing it is used to access
     #[stable_hasher(ignore)]
     pub hir_ref_id: HirId,

src/librustc_typeck/collect.rs

@@ -1353,7 +1353,7 @@ pub fn checked_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, fail: bool) -> Op
                                 None
                             }
                         }
-                        Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(path),
+                        Node::TraitRef(&hir::TraitRef { ref path, .. }) => Some(&**path),
                         _ => None,
                     };