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From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2008-06-21 03:08:13

David Abrahams wrote:
> Yesterday someone on the user's list posted a message
> ( about a
> "compilation error in the boost code:"
> s-test.h:49: instantiated from here
> /usr/include/boost/archive/detail/oserializer.hpp:567: error: invalid
> application of 'sizeof' to incomplete
> type 'boost::STATIC_ASSERTION_FAILURE<false>'
> make: *** [stest] Error 1
> and proceeded to try to analyze the BOOST_STATIC_ASSERT implementation
> to see what was wrong with it. Granted, most people figure out what a
> static assertion is supposed to be, but still, the error message gave no
> clue about what might have gone wrong... no clue to the user, and no
> clue to anyone reading his posting, unless they were going to look up
> the line in the source file... oops, I take it back. My copy of
> oserializer.hpp doesn't even have a line 567, and the posting doesn't
> indicate which version the user has.
> For several releases now we've had a suite of static assertion tools
> that give far superior error messages to what BOOST_STATIC_ASSERT can
> provide
> (
> I think <radical-idea>it's time to deprecate
> BOOST_STATIC_ASSERT</radical-idea> or at *least* put a prominent note in
> its documentation directing people at the BOOST_MPL_ASSERT macros.
> Thoughts?

As a user and a library writer I would ask to keep BOOST_STATIC_ASSERT
as it is without deprecation. I'm using this macro on a regular basis
and found no problems with it. I usually put a comment near the macro
that explains what the check does and I'm very sure the comment will be
far more informative than any compiler-generated error message (unless
we are speaking of static_assert in C++0x).

I wouldn't like to move to BOOST_MPL_ASSERT since (a) it would require
to change my code (b) it would complicate condition expressions with
compile-time constants and (c) it would introduce dependency on MPL
where there was no such dependency. However, I think pointers to MPL
docs near BOOST_STATIC_ASSERT description is a good idea.

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