Ivan Vecerina wrote:
I've noticed discussions about this a couple of years ago. For assert-style macros that include multiple statements, a common idiom is to enclose the statements in a do{...}while(0) dummy loop. This makes the macro behave like a single statement.
A problem with some compilers (notably VC7.x) is that this triggers a warning (C4127: conditional expression is constant).
The workaround adopted by boost is to automatically disable this warning -- which however can be legitimate and useful in user code.
I think I have found a better 'always-false' condition which does not trigger a warning, and works at least in VC7.1: do{ }while(__LINE__==-1)
Do you see a problem with this approach? <snip>
It works in VC++ 7.1 if you enable "edit and continue", because this results in non-standard expansion of the __LINE__ macro to an expression that isn't a compile-time constant. In general it doesn't work.