Mac Forum / Programming / CodeWarrior / December 2005

But, MSL on OS X is usually built to use the System C library. A more
interesting question is whether to use the Metrowerks C++ library or not.

I was going to write that a huge advantage of MSL was the "debug mode"
where many common errors in the usage of C++ library throw exceptions
rather than just silently running off into the weeds.

<http://groups.google.com/groups?q=_MSL_DEBUG>
especially Howard Hinnant's posting:
<http://groups.google.com/groups?q=STL+Debug+Mode+Tip+24>

but in researching this posting, I was pleased to discover that gcc's
stl also has a debug mode, as documented in:

<http://gcc.gnu.org/onlinedocs/libstdc++/debug.html>

"To use the libstdc++ debug mode, compile your application with the
compiler flag -D_GLIBCXX_DEBUG. Note that this flag changes the sizes
and behavior of standard class templates such as std::vector, and
therefore you can only link code compiled with debug mode and code
compiled without debug mode if no instantiation of a container is passed
between the two translation units."

"The libstdc++ debug mode performs checking for many areas of the C++
standard, but the focus is on checking interactions among standard
iterators, containers, and algorithms, including:

     "Safe iterators: Iterators keep track of the container whose
elements they reference, so errors such as incrementing a past-the-end
iterator or dereferencing an iterator that points to a container that
has been destructed are diagnosed immediately.
     
     "Algorithm preconditions: Algorithms attempt to validate their
input parameters to detect errors as early as possible. For instance,
the set_intersection algorithm requires that its iterator parameters
first1 and last1 form a valid iterator range, and that the sequence
[first1, last1) is sorted according to the same predicate that was
passed to set_intersection; the libstdc++ debug mode will detect an
error if the sequence is not sorted or was sorted by a different
predicate."