From a1a03d6555892e12d4d9f789e4390793d16601b4 Mon Sep 17 00:00:00 2001
From: proberts <proberts@cinesite.com>
Date: Thu, 16 Feb 2023 19:21:16 +0000
Subject: [PATCH] RunTimeTyped : IECore::assertedStaticCast allow null source
 pointer

* use approach taken by boost polymorphic_downcast and compare source
  pointer to casted pointer, this has added benefit of not compiling
  if Target type cannot be converted to Source type so should detect
  programming errors at compile time.
---
 include/IECore/RunTimeTyped.inl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/IECore/RunTimeTyped.inl b/include/IECore/RunTimeTyped.inl
index 584942bbd4..4a01bf8f37 100644
--- a/include/IECore/RunTimeTyped.inl
+++ b/include/IECore/RunTimeTyped.inl
@@ -71,14 +71,14 @@ T *runTimeCast( S *src )
 template<typename T, typename S>
 boost::intrusive_ptr<T> assertedStaticCast( const boost::intrusive_ptr<S> &src )
 {
-	assert( runTimeCast<T>( src ) );
+	assert( runTimeCast<T>( src ) == src ); // NOTE : see boost polymorphic_downcast
 	return boost::static_pointer_cast<T>( src );
 }
 
 template<typename T, typename S>
 T* assertedStaticCast( S* src )
 {
-	assert( runTimeCast<T>( src ) );
+	assert( runTimeCast<T>( src ) == src ); // NOTE : see boost polymorphic_downcast
 	return static_cast<T *>( src );
 }