From fed58f315a0175f3bc4f8f84a23c5062fd69ced6 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Tue, 21 Feb 2017 12:23:47 -0500
Subject: [PATCH] store the visit order in the Crate

---
 src/librustc/dep_graph/visit.rs               | 28 ++-----------------
 src/librustc/hir/lowering.rs                  | 10 +++++++
 src/librustc/hir/mod.rs                       |  6 ++++
 .../calculate_svh/svh_visitor.rs              |  1 +
 4 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/src/librustc/dep_graph/visit.rs b/src/librustc/dep_graph/visit.rs
index 0d10049bc1e4e..a34a3591c151d 100644
--- a/src/librustc/dep_graph/visit.rs
+++ b/src/librustc/dep_graph/visit.rs
@@ -11,7 +11,6 @@
 use hir;
 use hir::def_id::DefId;
 use hir::itemlikevisit::ItemLikeVisitor;
-use hir::intravisit::{self, NestedVisitorMap, Visitor};
 use ty::TyCtxt;
 
 use super::dep_node::DepNode;
@@ -79,30 +78,9 @@ pub fn visit_all_item_likes_in_krate<'a, 'tcx, V, F>(tcx: TyCtxt<'a, 'tcx, 'tcx>
 pub fn visit_all_bodies_in_krate<'a, 'tcx, C>(tcx: TyCtxt<'a, 'tcx, 'tcx>, callback: C)
     where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
 {
-    // NB: we use a visitor here rather than walking the keys of the
-    // hashmap so as to ensure we visit the bodies "in order".
-
     let krate = tcx.hir.krate();
-    intravisit::walk_crate(&mut V { tcx, callback }, krate);
-
-    struct V<'a, 'tcx: 'a, C> {
-        tcx: TyCtxt<'a, 'tcx, 'tcx>,
-        callback: C
-    }
-
-    impl<'a, 'tcx, C> Visitor<'tcx> for V<'a, 'tcx, C>
-        where C: Fn(/* body_owner */ DefId, /* body id */ hir::BodyId),
-    {
-        fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
-            NestedVisitorMap::All(&self.tcx.hir)
-        }
-
-        fn visit_body(&mut self, body: &'tcx hir::Body) {
-            let body_id = body.id();
-            let body_owner_def_id = self.tcx.hir.body_owner_def_id(body_id);
-            (self.callback)(body_owner_def_id, body_id);
-
-            intravisit::walk_body(self, body);
-        }
+    for &body_id in &krate.body_ids {
+        let body_owner_def_id = tcx.hir.body_owner_def_id(body_id);
+        callback(body_owner_def_id, body_id);
     }
 }
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index c12de6807b103..77f11c94c2128 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -185,6 +185,7 @@ impl<'a> LoweringContext<'a> {
         let module = self.lower_mod(&c.module);
         let attrs = self.lower_attrs(&c.attrs);
         let exported_macros = c.exported_macros.iter().map(|m| self.lower_macro_def(m)).collect();
+        let body_ids = body_ids(&self.bodies);
 
         hir::Crate {
             module: module,
@@ -195,6 +196,7 @@ impl<'a> LoweringContext<'a> {
             trait_items: self.trait_items,
             impl_items: self.impl_items,
             bodies: self.bodies,
+            body_ids: body_ids,
         }
     }
 
@@ -2408,3 +2410,11 @@ impl<'a> LoweringContext<'a> {
         }
     }
 }
+
+fn body_ids(bodies: &BTreeMap<hir::BodyId, hir::Body>) -> Vec<hir::BodyId> {
+    // Sorting by span ensures that we get things in order within a
+    // file, and also puts the files in a sensible order.
+    let mut body_ids: Vec<_> = bodies.keys().cloned().collect();
+    body_ids.sort_by_key(|b| bodies[b].value.span);
+    body_ids
+}
diff --git a/src/librustc/hir/mod.rs b/src/librustc/hir/mod.rs
index 6f03073c803c6..8715c89c6540d 100644
--- a/src/librustc/hir/mod.rs
+++ b/src/librustc/hir/mod.rs
@@ -410,6 +410,12 @@ pub struct Crate {
     pub trait_items: BTreeMap<TraitItemId, TraitItem>,
     pub impl_items: BTreeMap<ImplItemId, ImplItem>,
     pub bodies: BTreeMap<BodyId, Body>,
+
+    /// A list of the body ids written out in the order in which they
+    /// appear in the crate. If you're going to process all the bodies
+    /// in the crate, you should iterate over this list rather than the keys
+    /// of bodies.
+    pub body_ids: Vec<BodyId>,
 }
 
 impl Crate {
diff --git a/src/librustc_incremental/calculate_svh/svh_visitor.rs b/src/librustc_incremental/calculate_svh/svh_visitor.rs
index c7512f2971b33..40e534e25e998 100644
--- a/src/librustc_incremental/calculate_svh/svh_visitor.rs
+++ b/src/librustc_incremental/calculate_svh/svh_visitor.rs
@@ -1166,6 +1166,7 @@ impl<'a, 'hash, 'tcx> StrictVersionHashVisitor<'a, 'hash, 'tcx> {
             trait_items: _,
             impl_items: _,
             bodies: _,
+            body_ids: _,
         } = *krate;
 
         visit::Visitor::visit_mod(self, module, span, ast::CRATE_NODE_ID);