ir: Handle properly template instantiation specializations in clang >3.9.

This fixes tests/expectations/tests/type_alias_template_specialized.rs in those
clang versions (without regressions, hopefully), and makes the behavior the
proper one, without needing replacements.

Author: emilio

src/ir/context.rs

@@ -299,6 +299,8 @@ impl<'ctx> BindgenContext<'ctx> {
         let id = item.id();
         let is_type = item.kind().is_type();
         let is_unnamed = is_type && item.expect_type().name().is_none();
+        let is_template_instantiation =
+            is_type && item.expect_type().is_template_instantiation();
 
         // Be sure to track all the generated children under namespace, even
         // those generated after resolving typerefs, etc.
@@ -317,7 +319,7 @@ impl<'ctx> BindgenContext<'ctx> {
         // Unnamed items can have an USR, but they can't be referenced from
         // other sites explicitly and the USR can match if the unnamed items are
         // nested, so don't bother tracking them.
-        if is_type && declaration.is_some() {
+        if is_type && !is_template_instantiation && declaration.is_some() {
             let mut declaration = declaration.unwrap();
             if !declaration.is_valid() {
                 if let Some(location) = location {

src/ir/template.rs

@@ -251,25 +251,30 @@ impl TemplateInstantiation {
                 }
             });
 
-        let definition = ty.declaration()
-            .specialized()
-            .or_else(|| {
-                let mut template_ref = None;
-                ty.declaration().visit(|child| {
-                    if child.kind() == CXCursor_TemplateRef {
-                        template_ref = Some(child);
-                        return CXVisit_Break;
-                    }
+        let declaration = ty.declaration();
+        let definition = if declaration.kind() == CXCursor_TypeAliasTemplateDecl {
+            Some(declaration)
+        } else {
+            declaration
+                .specialized()
+                .or_else(|| {
+                    let mut template_ref = None;
+                    ty.declaration().visit(|child| {
+                        if child.kind() == CXCursor_TemplateRef {
+                            template_ref = Some(child);
+                            return CXVisit_Break;
+                        }
 
-                    // Instantiations of template aliases might have the
-                    // TemplateRef to the template alias definition arbitrarily
-                    // deep, so we need to recurse here and not only visit
-                    // direct children.
-                    CXChildVisit_Recurse
-                });
+                        // Instantiations of template aliases might have the
+                        // TemplateRef to the template alias definition arbitrarily
+                        // deep, so we need to recurse here and not only visit
+                        // direct children.
+                        CXChildVisit_Recurse
+                    });
 
-                template_ref.and_then(|cur| cur.referenced())
-            });
+                    template_ref.and_then(|cur| cur.referenced())
+                })
+        };
 
         let definition = match definition {
             Some(def) => def,

src/ir/ty.rs

@@ -109,6 +109,14 @@ impl Type {
         }
     }
 
+    /// Is this a template instantiation type?
+    pub fn is_template_instantiation(&self) -> bool {
+        match self.kind {
+            TypeKind::TemplateInstantiation(..) => true,
+            _ => false,
+        }
+    }
+
     /// Is this a template alias type?
     pub fn is_template_alias(&self) -> bool {
         match self.kind {