Re: [PATCH] assert.h: allow gcc to detect assert(a = 1) errors

[Roland McGrath <roland at hack dot frob dot com>]

This certainly should not go in during the current release freeze.
So you might not want to try to get too much discussion going until
the floodgates reopen.  Also, various key people might be less than
usually responsive until after Cauldron (and for me, another week of
vacation thereafter).

Isn't there an "empty statement" warning that might be on too?  We
certainly don't want the internals of the macro (the then clause in
your new version) to produce warnings of their own with any possible
combination of switches.

You should be able to use __extension__ for GCC under -ansi.  But
perhaps that would wrongly allow use of extensions inside the user's
expression too.  If you're avoiding it for good reason, there should
be comments there explaining why.

I also wonder how modern GCCs running in integrated preprocessor
mode deal with the system header exception and/or __extension__ for
this sort of case (since in integrated preprocessor mode it can tell
which part came from the system header and which from the user).

Any change like this is going to need a lot of detailed reporting
about testing with different compilers and option combinations and
sorts of expressions (i.e. ones using extensions or not and perhaps
various different sorts of extensions).


Thanks,
Roland