On Thu, Apr 15, 2004 at 10:46:23AM +0400, Vladimir Prus wrote:
Hello, I've just found out that the following program:
#include <boost/static_assert.hpp>
int main() { BOOST_STATIC_ASSERT(false); return 0; }
compiled with gcc 3.3 produces:
sa.cpp:6: error: invalid application of `sizeof' to an incomplete type
I'm kinda hijacking your message topic (apologies) but... More generally, I would really like a Boost library which lets me generate custom error messages portably. For example, with FC++, I spent a bit of time getting g++ to give "nice" diagnostics for certain kinds of errors -- for instance, compiling // uh oh... cout << lambda(X,X)[ X ](1,2) << endl; // lam2.cpp line 94 with g++-3.1.1 yields lambda.hpp: In function `boost::fcpp::lambda_impl::LambdaThingy< boost::fcpp::lambda_impl::exp::CONS< boost::fcpp::lambda_impl::exp::lambda_var<i>, boost::fcpp::lambda_impl::exp::CONS< boost::fcpp::lambda_impl::exp::lambda_var<i>, boost::fcpp::lambda_impl::exp::NIL> > > boost::fcpp::lambda_impl::lambda(const boost::fcpp::lambda_impl::exp::lambda_var<i>&, const boost::fcpp::lambda_impl::exp::lambda_var<i>&) [with int i = 4, int j = 4]': lam2.cpp:94: instantiated from here lambda.hpp:1137: no method `boost::fcpp::lambda_impl:: YouCannotPassTheSameLambdaVarTo_lambda_MoreThanOnce<true>::go' I am happy with the last two lines of the error message, which indicate both the source of the problem (lam2.cpp, line 94) and the issue (YouCannotPassTheSameLambdaVarTo_lambda_MoreThanOnce). However I got this working using completely ad-hoc techniques which maybe only work well for g++-3.1.1. What I would really love is if there were a boost library which enabled me to dispatch messages along the lines of BOOST_CUSTOM_ERROR( b, msg ) BOOST_CUSTOM_WARNING( b, msg ) where in both cases "b" is a compile-time boolean, "msg" is the name of a type, and the behavior is if the boolean is true force this compiler to generate a short diagnostic with typename "msg" featured prominently In the long run, there really needs to be language support for meta-programs to generate legible diagnostics, but in the meantime, I would love a stopgap solution along the lines above. I think it would "only" involve the work of finding the best "trick" for each compiler brand/version. Perhaps a little concerted effort would discover one trick which worked well across many compilers. Is there interest in this? -- -Brian McNamara (lorgon@cc.gatech.edu)