Auto merge of #640 - fitzgen:stylo-stuff, r=emilio

More fixes for Stylo

See each commit message for details. bce1330 is the big correctness fix for a bug we were hitting in stylo.

r? @emilio

Author: bors-servo

src/codegen/mod.rs

@@ -21,8 +21,8 @@ use ir::item_kind::ItemKind;
 use ir::layout::Layout;
 use ir::module::Module;
 use ir::objc::{ObjCInterface, ObjCMethod};
-use ir::template::{AsNamed, TemplateInstantiation};
-use ir::ty::{TemplateDeclaration, Type, TypeKind};
+use ir::template::{AsNamed, TemplateInstantiation, TemplateParameters};
+use ir::ty::{Type, TypeKind};
 use ir::var::Var;
 
 use std::borrow::Cow;
@@ -2647,8 +2647,10 @@ impl TryToRustTy for TemplateInstantiation {
                 // This can happen if we generated an opaque type for a partial
                 // template specialization, and we've hit an instantiation of
                 // that partial specialization.
-                extra_assert!(ctx.resolve_type_through_type_refs(decl)
-                                  .is_opaque());
+                extra_assert!(decl.into_resolver()
+                                  .through_type_refs()
+                                  .resolve(ctx)
+                                  .is_opaque(ctx));
                 return Err(error::Error::InstantiationOfOpaqueType);
             }
         };

src/ir/comp.rs

@@ -6,7 +6,7 @@ use super::derive::{CanDeriveCopy, CanDeriveDebug, CanDeriveDefault};
 use super::item::Item;
 use super::layout::Layout;
 use super::traversal::{EdgeKind, Trace, Tracer};
-use super::ty::TemplateDeclaration;
+use super::template::TemplateParameters;
 use clang;
 use parse::{ClangItemParser, ParseError};
 use std::cell::Cell;
@@ -812,7 +812,7 @@ impl CompInfo {
     }
 }
 
-impl TemplateDeclaration for CompInfo {
+impl TemplateParameters for CompInfo {
     fn self_template_params(&self,
                             _ctx: &BindgenContext)
                             -> Option<Vec<ItemId>> {

src/ir/context.rs

@@ -6,9 +6,9 @@ use super::item::{Item, ItemCanonicalPath, ItemSet};
 use super::item_kind::ItemKind;
 use super::module::{Module, ModuleKind};
 use super::named::{UsedTemplateParameters, analyze};
-use super::template::TemplateInstantiation;
+use super::template::{TemplateInstantiation, TemplateParameters};
 use super::traversal::{self, Edge, ItemTraversal};
-use super::ty::{FloatKind, TemplateDeclaration, Type, TypeKind};
+use super::ty::{FloatKind, Type, TypeKind};
 use BindgenOptions;
 use cexpr;
 use callbacks::ParseCallbacks;
@@ -712,21 +712,6 @@ impl<'ctx> BindgenContext<'ctx> {
         }
     }
 
-    /// Resolve the given `ItemId` into a `Type`, and keep doing so while we see
-    /// `ResolvedTypeRef`s to other items until we get to the final `Type`.
-    pub fn resolve_type_through_type_refs(&self, item_id: ItemId) -> &Type {
-        assert!(self.collected_typerefs());
-
-        let mut id = item_id;
-        loop {
-            let ty = self.resolve_type(id);
-            match *ty.kind() {
-                TypeKind::ResolvedTypeRef(next_id) => id = next_id,
-                _ => return ty,
-            }
-        }
-    }
-
     /// Get the current module.
     pub fn current_module(&self) -> ItemId {
         self.current_module
@@ -1420,6 +1405,73 @@ impl<'ctx> BindgenContext<'ctx> {
     }
 }
 
+/// A builder struct for configuring item resolution options.
+#[derive(Debug, Copy, Clone)]
+pub struct ItemResolver {
+    id: ItemId,
+    through_type_refs: bool,
+    through_type_aliases: bool,
+}
+
+impl ItemId {
+    /// Create an `ItemResolver` from this item id.
+    pub fn into_resolver(self) -> ItemResolver {
+        self.into()
+    }
+}
+
+impl From<ItemId> for ItemResolver {
+    fn from(id: ItemId) -> ItemResolver {
+        ItemResolver::new(id)
+    }
+}
+
+impl ItemResolver {
+    /// Construct a new `ItemResolver` from the given id.
+    pub fn new(id: ItemId) -> ItemResolver {
+        ItemResolver {
+            id: id,
+            through_type_refs: false,
+            through_type_aliases: false,
+        }
+    }
+
+    /// Keep resolving through `Type::TypeRef` items.
+    pub fn through_type_refs(mut self) -> ItemResolver {
+        self.through_type_refs = true;
+        self
+    }
+
+    /// Keep resolving through `Type::Alias` items.
+    pub fn through_type_aliases(mut self) -> ItemResolver {
+        self.through_type_aliases = true;
+        self
+    }
+
+    /// Finish configuring and perform the actual item resolution.
+    pub fn resolve<'a, 'b>(self, ctx: &'a BindgenContext<'b>) -> &'a Item {
+        assert!(ctx.collected_typerefs());
+
+        let mut id = self.id;
+        loop {
+            let item = ctx.resolve_item(id);
+            let ty_kind = item.as_type().map(|t| t.kind());
+            match ty_kind {
+                Some(&TypeKind::ResolvedTypeRef(next_id)) if self.through_type_refs => {
+                    id = next_id;
+                }
+                // We intentionally ignore template aliases here, as they are
+                // more complicated, and don't represent a simple renaming of
+                // some type.
+                Some(&TypeKind::Alias(next_id)) if self.through_type_aliases => {
+                    id = next_id;
+                }
+                _ => return item,
+            }
+        }
+    }
+}
+
 /// A type that we are in the middle of parsing.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub struct PartialType {
@@ -1449,7 +1501,7 @@ impl PartialType {
     }
 }
 
-impl TemplateDeclaration for PartialType {
+impl TemplateParameters for PartialType {
     fn self_template_params(&self,
                             _ctx: &BindgenContext)
                             -> Option<Vec<ItemId>> {

src/ir/item.rs

@@ -8,9 +8,9 @@ use super::function::Function;
 use super::item_kind::ItemKind;
 use super::layout::Opaque;
 use super::module::Module;
-use super::template::AsNamed;
+use super::template::{AsNamed, TemplateParameters};
 use super::traversal::{EdgeKind, Trace, Tracer};
-use super::ty::{TemplateDeclaration, Type, TypeKind};
+use super::ty::{Type, TypeKind};
 use clang;
 use clang_sys;
 use parse::{ClangItemParser, ClangSubItemParser, ParseError, ParseResult};
@@ -830,7 +830,7 @@ impl DotAttributes for Item {
     }
 }
 
-impl TemplateDeclaration for ItemId {
+impl TemplateParameters for ItemId {
     fn self_template_params(&self,
                             ctx: &BindgenContext)
                             -> Option<Vec<ItemId>> {
@@ -839,15 +839,15 @@ impl TemplateDeclaration for ItemId {
     }
 }
 
-impl TemplateDeclaration for Item {
+impl TemplateParameters for Item {
     fn self_template_params(&self,
                             ctx: &BindgenContext)
                             -> Option<Vec<ItemId>> {
         self.kind.self_template_params(ctx)
     }
 }
 
-impl TemplateDeclaration for ItemKind {
+impl TemplateParameters for ItemKind {
     fn self_template_params(&self,
                             ctx: &BindgenContext)
                             -> Option<Vec<ItemId>> {