Feature/as refactor (shader-slang#817)

* Made dynamicCast a free function.

* Replace As with as or dynamicCast depending on if it is a type.

* Fix problem with using non smart pointer cast.

* Removed legacy asXXXX methods.

* Remove As from Type.

* Removed As from Qual type -> made coercable into Type*, such that can just use free 'as'.

* Remove left over QualType::As() impl.

* Remove As from SyntaxNodeBase.

* Made as for instructions implemented by dynamicCast.

* Replace As on DeclRef. Use the global as<> to do the cast.

* Add const safe versions of dynamicCast and as for IRInst

Author: jsmall-zzz

source/core/smart-pointer.h

@@ -63,30 +63,31 @@ namespace Slang
         {
             return referenceCount;
         }
-
-        // Use instead of dynamic_cast as it allows for replacement without using Rtti in the future
-        template<typename T>
-        SLANG_FORCE_INLINE const T* dynamicCast() const
-        {
-            return dynamic_cast<const T*>(this);
-        }
-        template<typename T>
-        SLANG_FORCE_INLINE T* dynamicCast()
-        {
-            return dynamic_cast<T*>(this);
-        }
     };
 
-    inline void addReference(RefObject* obj)
+    SLANG_FORCE_INLINE void addReference(RefObject* obj)
     {
         if(obj) obj->addReference();
     }
 
-    inline void releaseReference(RefObject* obj)
+    SLANG_FORCE_INLINE void releaseReference(RefObject* obj)
     {
         if(obj) obj->releaseReference();
     }
 
+    // For straight dynamic cast.
+    // Use instead of dynamic_cast as it allows for replacement without using Rtti in the future
+    template <typename T>
+    SLANG_FORCE_INLINE T* dynamicCast(RefObject* obj) { return dynamic_cast<T*>(obj); }
+    template <typename T>
+    SLANG_FORCE_INLINE const T* dynamicCast(const RefObject* obj) { return dynamic_cast<const T*>(obj); }
+
+    // Like a dynamicCast, but allows a type to implement a specific implementation that is suitable for it
+    template <typename T>
+    SLANG_FORCE_INLINE T* as(RefObject* obj) { return dynamicCast<T>(obj); }
+    template <typename T>
+    SLANG_FORCE_INLINE const T* as(const RefObject* obj) { return dynamicCast<T>(obj); }
+
     // "Smart" pointer to a reference-counted object
     template<typename T>
     struct RefPtr
@@ -182,9 +183,15 @@ namespace Slang
 		}
 
         template<typename U>
-        RefPtr<U> As() const
+        RefPtr<U> dynamicCast() const
+        {
+            return RefPtr<U>(Slang::dynamicCast<U>(pointer));
+        }
+
+        template<typename U>
+        RefPtr<U> as() const
         {
-            return RefPtr<U>(pointer->template dynamicCast<U>());
+            return RefPtr<U>(Slang::as<U>(pointer));
         }
 
         ~RefPtr()
@@ -238,4 +245,4 @@ namespace Slang
 	};
 }
 
-#endif
+#endif