TLDR: It seems pretty trivial to add support for them in all contexts, which can be pretty convenient.

I am currently working on augmenting AS' registration system with a little utility to save on boilerplate. Among this is the ability to wrap a factory function for a reference type so that it also registers the new object with the reference counter. This wrapper can't be a template method, because it relies on partial template specialization to deduce the function arguments, which isn't available for methods. This establishes the need to somehow pass a reference to the reference counter to this wrapper.. And `asCALL_CDECL_OBJ[LAST|FIRST]` seems like the perfect fit! However, since factory behaviors are not methods, angelscript refuses to register it with the necessary calling convention! I've gone ahead and simply enabled support for non-methods with the aforementioned calling conventions and it seems to work flawlessly!

Of course it's totally possible that everything will explode, crash and burn any second now, but ignoring that, the restriction here seems pretty arbitrary.

@WitchLord Sorry, what I forgot to mention was that the pointer passed to the function being registered would simply be the auxiliary pointer, for which all the necessary logic seems to already exist.

Here's a .diff of all that this change would encompass to my understanding:

diff --git a/sdk/angelscript/source/as_callfunc.cpp b/sdk/angelscript/source/as_callfunc.cpp
index 4941967e..c208d36f 100644
--- a/sdk/angelscript/source/as_callfunc.cpp
+++ b/sdk/angelscript/source/as_callfunc.cpp
@@ -71,6 +71,19 @@ int DetectCallingConvention(bool isMethod, const asSFuncPtr &ptr, int callConv,
 	}
 
 	asDWORD base = callConv;
+	if ( base == asCALL_CDECL_OBJFIRST || base == asCALL_CDECL_OBJLAST )
+	{
+		internal->callConv =
+			base == asCALL_CDECL_OBJFIRST ? ICC_CDECL_OBJFIRST : ICC_CDECL_OBJLAST;
+		if ( !isMethod )
+		{
+			if ( auxiliary == 0 )
+				return asINVALID_ARG;
+			internal->auxiliary = auxiliary;
+		}
+		return 0;
+	}
+
 	if( !isMethod )
 	{
 		if( base == asCALL_CDECL )
@@ -151,11 +164,7 @@ int DetectCallingConvention(bool isMethod, const asSFuncPtr &ptr, int callConv,
 		}
 		else
 #endif
-		if( base == asCALL_CDECL_OBJLAST )
-			internal->callConv = ICC_CDECL_OBJLAST;
-		else if( base == asCALL_CDECL_OBJFIRST )
-			internal->callConv = ICC_CDECL_OBJFIRST;
-		else if (base == asCALL_GENERIC)
+		if (base == asCALL_GENERIC)
 		{
 			internal->callConv = ICC_GENERIC_METHOD;
 			internal->auxiliary = auxiliary;