Use class templates for Null objects
This allows partial-instantiating custom Null object for template Lookup<T>.
Before, this had to be handcoded per instantiation. Apparently I missed
adding one for AAT::ankr.lookupTable, so it was getting the wrong (generic)
null for Lookup object, which is wrong and unsafe.
Fixes https://bugs.chromium.org/p/chromium/issues/detail?id=944346
diff --git a/src/hb-null.hh b/src/hb-null.hh
index 204c2fe..baddd99 100644
--- a/src/hb-null.hh
+++ b/src/hb-null.hh
@@ -105,15 +105,18 @@
/* Generic nul-content Null objects. */
template <typename Type>
-static inline Type const & Null () {
- static_assert (hb_null_size (Type) <= HB_NULL_POOL_SIZE, "Increase HB_NULL_POOL_SIZE.");
- return *reinterpret_cast<Type const *> (_hb_NullPool);
-}
+struct Null {
+ static Type const & get_null ()
+ {
+ static_assert (hb_null_size (Type) <= HB_NULL_POOL_SIZE, "Increase HB_NULL_POOL_SIZE.");
+ return *reinterpret_cast<Type const *> (_hb_NullPool);
+ }
+};
template <typename QType>
struct NullHelper
{
typedef typename hb_remove_const (typename hb_remove_reference (QType)) Type;
- static const Type & get_null () { return Null<Type> (); }
+ static const Type & get_null () { return Null<Type>::get_null (); }
};
#define Null(Type) NullHelper<Type>::get_null ()
@@ -122,9 +125,11 @@
} /* Close namespace. */ \
extern HB_INTERNAL const unsigned char _hb_Null_##Namespace##_##Type[Namespace::Type::null_size]; \
template <> \
- /*static*/ inline const Namespace::Type& Null<Namespace::Type> () { \
- return *reinterpret_cast<const Namespace::Type *> (_hb_Null_##Namespace##_##Type); \
- } \
+ struct Null<Namespace::Type> { \
+ static Namespace::Type const & get_null () { \
+ return *reinterpret_cast<const Namespace::Type *> (_hb_Null_##Namespace##_##Type); \
+ } \
+ }; \
namespace Namespace { \
static_assert (true, "Just so we take semicolon after.")
#define DEFINE_NULL_NAMESPACE_BYTES(Namespace, Type) \
@@ -134,10 +139,12 @@
#define DECLARE_NULL_INSTANCE(Type) \
extern HB_INTERNAL const Type _hb_Null_##Type; \
template <> \
- /*static*/ inline const Type& Null<Type> () { \
- return _hb_Null_##Type; \
- } \
-static_assert (true, "Just so we take semicolon after.")
+ struct Null<Type> { \
+ static Type const & get_null () { \
+ return _hb_Null_##Type; \
+ } \
+ }; \
+ static_assert (true, "Just so we take semicolon after.")
#define DEFINE_NULL_INSTANCE(Type) \
const Type _hb_Null_##Type
