OK, I guess I found the answer by myself:
http://cnicholson.net/2009/02/stupid-c-tricks-adventures-in-assert/ gives the explanation.
It is actually a common practice to wrap multi-line macros in do { } while (false);
. This is a workaround to allow for using those macros, e.g., in un-braced if else
.
if (condition_a)
MULTI_LINE_MACRO();
else
MULTI_LINE_MACRO_2();
The result would be that unexpectedly only the first line gets executed, which definitely leads to unexpected behaviour. So they were not entirely incompetent I guess...
http://kernelnewbies.org/FAQ/DoWhile0 also explains why my solution would not work. The MULTI_LINE_MACRO();
within the if would expand, e.g., to
if (condition_a)
{ /* macro stuff */ }
;
else // << never executed because of the ; above.
So I guess I have to disable the warning. GCC has a workaroud for this ( ({ MACRO })
), called a Statement Expression, but I don't think this works on VS2010.