incr.comp.: Do some various cleanup.

src/librustc/hir/def_id.rs

@@ -97,6 +97,17 @@ impl serialize::UseSpecializedDecodable for CrateNum {
            RustcDecodable, Hash, Copy)]
 pub struct DefIndex(u32);
 
+impl Idx for DefIndex {
+    fn new(value: usize) -> Self {
+        assert!(value < (u32::MAX) as usize);
+        DefIndex(value as u32)
+    }
+
+    fn index(self) -> usize {
+        self.0 as usize
+    }
+}
+
 impl fmt::Debug for DefIndex {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f,

src/librustc/hir/map/mod.rs

@@ -876,20 +876,10 @@ impl<'hir> Map<'hir> {
 
             Some(RootCrate(_)) => self.forest.krate.span,
             Some(NotPresent) | None => {
-                // Some nodes, notably macro definitions, are not
-                // present in the map for whatever reason, but
-                // they *do* have def-ids. So if we encounter an
-                // empty hole, check for that case.
-                if let Some(def_index) = self.definitions.opt_def_index(id) {
-                    let def_path_hash = self.definitions.def_path_hash(def_index);
-                    self.dep_graph.read(def_path_hash.to_dep_node(DepKind::Hir));
-                    DUMMY_SP
-                } else {
                 bug!("hir::map::Map::span: id not in map: {:?}", id)
             }
         }
     }
-    }
 
     pub fn span_if_local(&self, id: DefId) -> Option<Span> {
         self.as_local_node_id(id).map(|id| self.span(id))

src/librustc_driver/pretty.rs

@@ -20,7 +20,6 @@ use {abort_on_err, driver};
 use rustc::ty::{self, TyCtxt, GlobalArenas, Resolutions};
 use rustc::cfg;
 use rustc::cfg::graphviz::LabelledCFG;
-use rustc::dep_graph::DepGraph;
 use rustc::middle::cstore::CrateStore;
 use rustc::session::Session;
 use rustc::session::config::{Input, OutputFilenames};
@@ -848,9 +847,6 @@ pub fn print_after_parsing(sess: &Session,
                            krate: &ast::Crate,
                            ppm: PpMode,
                            ofile: Option<&Path>) {
-    let dep_graph = DepGraph::new(false);
-    let _ignore = dep_graph.in_ignore();
-
     let (src, src_name) = get_source(input, sess);
 
     let mut rdr = &*src;
@@ -893,9 +889,6 @@ pub fn print_after_hir_lowering<'tcx, 'a: 'tcx>(sess: &'a Session,
                                                 output_filenames: &OutputFilenames,
                                                 opt_uii: Option<UserIdentifiedItem>,
                                                 ofile: Option<&Path>) {
-    let dep_graph = DepGraph::new(false);
-    let _ignore = dep_graph.in_ignore();
-
     if ppm.needs_analysis() {
         print_with_analysis(sess,
                             cstore,