Auto merge of rust-lang#175 - jeanphilippeD:issue136, r=fitzgen,emilio

clang::Type::template_args return Option<TypeTemplateArgIterator>

Fix rust-lang#136 by providing a bound checked iterator replacing the interface.

Author: bors-servo

src/clang.rs

@@ -644,25 +644,22 @@ impl Type {
         Ok(Layout::new(size, align))
     }
 
-    /// If this type is a class template specialization, return its number of
+    /// If this type is a class template specialization, return its
     /// template arguments. Otherwise, return None.
-    pub fn num_template_args(&self) -> Option<u32> {
+    pub fn template_args(&self) -> Option<TypeTemplateArgIterator> {
         let n = unsafe { clang_Type_getNumTemplateArguments(self.x) };
         if n >= 0 {
-            Some(n as u32)
+            Some(TypeTemplateArgIterator {
+                x: self.x,
+                length: n as u32,
+                index: 0
+            })
         } else {
             debug_assert_eq!(n, -1);
             None
         }
     }
 
-    /// Get the type of the `i`th template argument for this template
-    /// specialization.
-    pub fn template_arg_type(&self, i: u32) -> Type {
-        let n = i as c_int;
-        Type { x: unsafe { clang_Type_getTemplateArgumentAsType(self.x, n) } }
-    }
-
     /// Given that this type is a pointer type, return the type that it points
     /// to.
     pub fn pointee_type(&self) -> Type {
@@ -750,6 +747,33 @@ impl Type {
     }
 }
 
+/// An iterator for a type's template arguments.
+pub struct TypeTemplateArgIterator {
+    x: CXType,
+    length: u32,
+    index: u32
+}
+
+impl Iterator for TypeTemplateArgIterator {
+    type Item = Type;
+    fn next(&mut self) -> Option<Type> {
+        if self.index < self.length {
+            let idx = self.index as c_int;
+            self.index += 1;
+            Some(Type { x: unsafe { clang_Type_getTemplateArgumentAsType(self.x, idx) } })
+        } else {
+            None
+        }
+    }
+}
+
+impl ExactSizeIterator for TypeTemplateArgIterator {
+    fn len(&self) -> usize {
+        assert!(self.index <= self.length);
+        (self.length - self.index) as usize
+    }
+}
+
 /// A `SourceLocation` is a file, line, column, and byte offset location for
 /// some source text.
 pub struct SourceLocation {

src/ir/comp.rs

@@ -490,26 +490,24 @@ impl CompInfo {
 
         let mut ci = CompInfo::new(kind);
         ci.is_anonymous = cursor.is_anonymous();
-        ci.template_args = match ty.num_template_args() {
+        ci.template_args = match ty.template_args() {
             // In forward declarations and not specializations, etc, they are in
             // the ast, we'll meet them in CXCursor_TemplateTypeParameter
             None => vec![],
-            Some(len) => {
-                let mut list = Vec::with_capacity(len as usize);
-                for i in 0..len {
-                    let arg_type = ty.template_arg_type(i);
-                    if arg_type.kind() != CXType_Invalid {
-                        let type_id =
-                            Item::from_ty_or_ref(arg_type, None, None, ctx);
-
-                        list.push(type_id);
-                    } else {
-                        ci.has_non_type_template_params = true;
-                        warn!("warning: Template parameter is not a type");
-                    }
+            Some(arg_types) => {
+                let num_arg_types = arg_types.len();
+
+                let args = arg_types
+                    .filter(|t| t.kind() != CXType_Invalid)
+                    .map(|t| Item::from_ty_or_ref(t, None, None, ctx))
+                    .collect::<Vec<_>>();
+
+                if args.len() != num_arg_types {
+                    ci.has_non_type_template_params = true;
+                    warn!("warning: Template parameter is not a type");
                 }
 
-                list
+                args
             }
         };
 

src/ir/ty.rs

@@ -507,7 +507,7 @@ impl Type {
                     TypeKind::Function(signature)
                 // Same here, with template specialisations we can safely assume
                 // this is a Comp(..)
-                } else if ty.num_template_args().unwrap_or(0) > 0 {
+                } else if ty.template_args().map_or(false, |x| x.len() > 0) {
                     debug!("Template specialization: {:?}", ty);
                     let complex =
                         CompInfo::from_ty(potential_id, ty, location, ctx)