This demonstrates a bug in CF9+'s implementation of argumentCollections, as well as some weirdness with structCount()

argumentCollectionBug.cfm

<cfscript>
	function baseline(){
		var localData = {};

		localData.copiedBefore = structCopy(arguments);
		dummyTest(argumentcollection=arguments);
		localData.copiedAfter = structCopy(arguments);
		localData.copiedBefore.d = 4;
		localData.copiedAfter.d = 4;

		outputIt(localData);
	}

	function withoutDummyTest(){
		var localData = {};

		localData.copiedBefore =duplicate(arguments);
		//dummyTest(argumentcollection=arguments);
		localData.copiedAfter = duplicate(arguments);
		localData.copiedBefore.d = 4;
		localData.copiedAfter.d = 4;

		outputIt(localData);
	}

	function withDummyTestSeparateArgs(){
		var localData = {};

		localData.copiedBefore =structCopy(arguments);
		dummyTest(a=arguments.a, b=arguments.b, c=arguments.c);
		localData.copiedAfter = structCopy(arguments);
		localData.copiedBefore.d = 4;
		localData.copiedAfter.d = 4;

		outputIt(localData);
	}

	function dummyTest(){
	}


	function outputIt(struct){
		var keys			= structKeyList(struct.copiedAfter);
		var count			= structCount(struct.copiedAfter);
		var javaToString	= struct.copiedAfter.toString();
		var json			= serializeJson(struct.copiedAfter);
		var correctCount	= count eq 4;

		writeOutput("inner args:<br />");
		writeOutput("struct.copiedBefore.d = #struct.copiedBefore.d#<br />");
		dump(var=struct.copiedBefore, label="struct.copiedBefore");
		writeOutput("struct.copiedAfter.d = #struct.copiedAfter.d#<br />");
		dump(var=struct.copiedAfter, label="struct.copiedAfter");
		writeOutput("structCount is 4: #correctCount#<br />structCount(): #count#<br />structKeyList(): #keys#<br />toString(): #javaToString#<br />serializeJson(): #json#<br />");
	}

	writeOutput("<h3>baseline</h3>");
	baseline(a="1",b="2",c="3");
	writeOutput("<hr />");

	writeOutput("<h3>withoutDummyTest</h3>");
	withoutDummyTest(a="1",b="2",c="3");
	writeOutput("<hr />");

	writeOutput("<h3>withDummyTestSeparateArgs</h3>");
	withDummyTestSeparateArgs(a="1",b="2",c="3");
	writeOutput("<hr />");
</cfscript>


<cffunction name="dump">
	<cfdump var="#arguments.var#" label="#arguments.label#">
</cffunction>