Auto merge of #200 - fitzgen:replace-template-alias, r=emilio

Allow aliases and template aliases to be considered for replacement

Fixes #89.

I'm not exactly *happy* with the way this is implemented (making `real_canonical_name` public so that we can use it in replacement lookups) but I'm not sure of a better way without refactoring most of how naming works right now.

r? @emilio

Author: bors-servo

src/ir/context.rs

@@ -320,23 +320,27 @@ impl<'ctx> BindgenContext<'ctx> {
         let mut replacements = vec![];
 
         for (id, item) in self.items.iter() {
+            // Calls to `canonical_name` are expensive, so eagerly filter out
+            // items that cannot be replaced.
             let ty = match item.kind().as_type() {
                 Some(ty) => ty,
                 None => continue,
             };
 
-            // canonical_name calls are expensive.
-            let ci = match ty.as_comp() {
-                Some(ci) => ci,
-                None => continue,
-            };
-
-            if ci.is_template_specialization() {
-                continue;
+            match *ty.kind() {
+                TypeKind::Comp(ref ci) if !ci.is_template_specialization() => {}
+                TypeKind::TemplateAlias(_, _) |
+                TypeKind::Alias(_, _) => {}
+                _ => continue,
             }
 
-            if let Some(replacement) = self.replacements
-                .get(&item.canonical_name(self)) {
+            let name = item.real_canonical_name(self,
+                                                self.options()
+                                                    .enable_cxx_namespaces,
+                                                true);
+            let replacement = self.replacements.get(&name);
+
+            if let Some(replacement) = replacement {
                 if replacement != id {
                     // We set this just after parsing the annotation. It's
                     // very unlikely, but this can happen.

src/ir/item.rs

@@ -539,11 +539,11 @@ impl Item {
     ///
     /// This name should be derived from the immutable state contained in the
     /// type and the parent chain, since it should be consistent.
-    fn real_canonical_name(&self,
-                           ctx: &BindgenContext,
-                           count_namespaces: bool,
-                           for_name_checking: bool)
-                           -> String {
+    pub fn real_canonical_name(&self,
+                               ctx: &BindgenContext,
+                               count_namespaces: bool,
+                               for_name_checking: bool)
+                               -> String {
         let base_name = match *self.kind() {
             ItemKind::Type(ref ty) => {
                 match *ty.kind() {

tests/expectations/replace_template_alias.rs

@@ -0,0 +1,15 @@
+/* automatically generated by rust-bindgen */
+
+
+#![allow(non_snake_case)]
+
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct Rooted<T> {
+    pub ptr: MaybeWrapped<T>,
+}
+/// But the replacement type does use T!
+///
+/// <div rustbindgen replaces="MaybeWrapped" />
+pub type MaybeWrapped<T> = T;

tests/headers/replace_template_alias.hpp

@@ -0,0 +1,23 @@
+// bindgen-flags: -- --std=c++14
+
+namespace JS {
+namespace detail {
+
+/// Notice how this doesn't use T.
+template <typename T>
+using MaybeWrapped = int;
+
+}
+
+template <typename T>
+class Rooted {
+    detail::MaybeWrapped<T> ptr;
+};
+
+}
+
+/// But the replacement type does use T!
+///
+/// <div rustbindgen replaces="MaybeWrapped" />
+template <typename T>
+using replaces_MaybeWrapped = T;