codegen: Properly handle virtual bases.

Author: emilio

libbindgen/src/codegen/mod.rs

@@ -835,14 +835,18 @@ impl CodeGenerator for CompInfo {
         }
 
         for (i, base) in self.base_members().iter().enumerate() {
+            // Virtual bases are already taken into account by the vtable
+            // pointer.
+            //
+            // FIXME(emilio): Is this always right?
+            if base.is_virtual() {
+                continue;
+            }
+
             let base_ty = ctx.resolve_type(base.ty);
             // NB: We won't include unsized types in our base chain because they
             // would contribute to our size given the dummy field we insert for
             // unsized types.
-            //
-            // NB: Canonical type is here because it could be inheriting from a
-            // typedef, for example, and the lack of `unwrap()` is because we
-            // can inherit from a template parameter, yes.
             if base_ty.is_unsized(ctx) {
                 continue;
             }

libbindgen/src/ir/comp.rs

@@ -176,7 +176,7 @@ impl<'a> CanDeriveCopy<'a> for Field {
 
 
 /// The kind of inheritance a base class is using.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub enum BaseKind {
     /// Normal inheritance, like:
     ///
@@ -201,6 +201,13 @@ pub struct Base {
     pub kind: BaseKind,
 }
 
+impl Base {
+    /// Whether this base class is inheriting virtually.
+    pub fn is_virtual(&self) -> bool {
+        self.kind == BaseKind::Virtual
+    }
+}
+
 /// A compound type.
 ///
 /// Either a struct or union, a compound type is built up from the combination