Auto merge of #510 - fitzgen:cleanup-ir-graph-traversal, r=emilio

Cleanup IR graph traversal

This is a bunch of pre-cursor work to properly determining which template type parameters are actually used or not.

First three commits are mechanical / code motion / renaming.

Fourth is the meat of this PR, making a bunch of things more generic and introducing the concept of an `EdgeKind` in the IR graph.

Last commit is just `cargo fmt`.

r? @emilio

1 files changed, 3 insertions, 3 deletions

diff --git a/src/codegen/mod.rs b/src/codegen/mod.rs
index 99400f7a..b626fe34 100644
--- a/src/codegen/mod.rs
+++ b/src/codegen/mod.rs
@@ -12,13 +12,13 @@ use ir::derive::{CanDeriveCopy, CanDeriveDebug, CanDeriveDefault};
 use ir::enum_ty::{Enum, EnumVariant, EnumVariantValue};
 use ir::function::{Function, FunctionSig};
 use ir::int::IntKind;
-use ir::item::{Item, ItemAncestors, ItemCanonicalName, ItemCanonicalPath};
+use ir::item::{Item, ItemAncestors, ItemCanonicalName, ItemCanonicalPath,
+               ItemSet};
 use ir::item_kind::ItemKind;
 use ir::layout::Layout;
 use ir::module::Module;
 use ir::objc::ObjCInterface;
 use ir::ty::{Type, TypeKind};
-use ir::type_collector::ItemSet;
 use ir::var::Var;
 
 use std::borrow::Cow;
@@ -2190,7 +2190,7 @@ impl ToRustTy for Type {
                         .map(|arg| arg.to_rust_ty(ctx))
                         .collect::<Vec<_>>();
 
-                    path.segments.last_mut().unwrap().parameters = if
+                    path.segments.last_mut().unwrap().parameters = if 
                         template_args.is_empty() {
                         None
                     } else {