Why in the world does this compile?

This is a section of code compiled with C++/CLR. I don't believe it's important to know the details of what it is part of, but I will be happy to give them if asked. What perplexes me is the comma at the end of the line that begins with 'ihnxxx = ' . It is obviously my error; it should have been a semicolon. My puzzle is that the compiler accepted it without errors or warnings and the program runs fine. If I correct it, it runs exactly the same way; but if I substitute something else -- as for example a period or a colon -- the compiler flags it immediately (as it should). I dug into my archives and found that earlier versions of the program had the same mysterious comma; since the compiler never flagged it I never had any reason to review this passage.

Can anybody tell me what is going on?

	REFERENCE_TIME ihnxxx = 0;
	hr = pAudioIO -> ReadData(&cycleSize1, multiplier);	// &cycleSize1 to AudioIO
	// clumsy but OK. cycleSize1 is returned as 65536.
	// here cycleSize1 and &cycleSize1 are OK

	//printf("*****cycleSize1\t\t\t\t%d\n", cycleSize1);

	ihnxxx = (INT64)
		( one_full_second * cycleSize1 * multiplier/
			(double)(pWFE -> Format.nSamplesPerSec)),



	hr = pClient_R -> Initialize(
		AUDCLNT_SHAREMODE_SHARED,		// this only works for SHARED
		0,
		ihnxxx,							// this is the full size including multipliers
		0,
		pNFormat_R,
		NULL);

	if (hr) numberOfErrors++;