In gcc/g++ version 4.0 there is no way to turn off the unused variable warning enabled by -Wall with a command line switch.
I think this is a bug: it should be possible to selectively turn on or off all warnings (on the command line). The advice in the documentation is to attach __attribute__((unused)) to the selected variable. This may be inappropriate for three distinct reasons: (a) It is a GNU extension (b) it clutters the code (c) It isn't always easy to tell if a variable is unused Comment (c) means: C/C++ code is not always hand written. In my case I am generating code that sometimes contains an unused variable as a result of a conservative optimisation failing to detect the variable is not required. I can of course just enable all the warnings selected by -Wall, other than the unused warning .. but this has two problems: (a) it is gcc version specific which warnings can be produced, so it would be necessary to generate and consult configuation data .. this may not be possible in a cross compilation situation (where a process is preparing script to be executed on another machine, for example). (b) it makes a real mess of the build having such long command lines .. (gcc provides lots of warnings :) BTW: gcc/g++ 4.0 is one heck of a better compiler than the 3.x series! Nice work!! [Pls CC me as I don't subscribe to this list] -- John Skaller <skaller at users dot sourceforge dot net>
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