Fwd: RE: [Cmake] Fwd: [Insight-developers] Debug vs. RelWithDebInfo

[Bill Hoffman]

>Reply-To: <ian.m.scott@stud.man.ac.uk>
>From: "Ian Scott" <ian.m.scott@stud.man.ac.uk>
>To: "'Bill Hoffman'" <bill.hoffman@kitware.com>
>Cc: "Cmake@Public. Kitware. Com \(E-mail\)" <cmake@public.kitware.com>
>Subject: RE: [Cmake] Fwd: [Insight-developers] Debug vs. RelWithDebInfo
>Date: Mon, 29 Oct 2001 16:07:20 -0000
>X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2910.0)
>Importance: Normal
>
>The difference between Debug and RelwithDebInfo is that RelwithDebInfo is
>quite similar to Release mode. It produces fully optimised code, but also
>builds the program database, and inserts debug line information to give a
>debugger a good chance at guessing where in the code you are at any time.
>When VXL was still using ordinary .dsp files, it was one of the build modes
>several of us found very useful.
>
>In my own case I use it for the following things.
>-Debugging heisenbugs (bugs that are in release mode, but disappear when you
>switch to the debug mode build.
>-Attaching a debugger to long running programs (some of mine take a week) to
>see if they have hung.
>-Doing quick debugs when you aren't too fussed about the accuracy of the
>debugger.
>
>I added this (after discussing it on the CMake reflector) as a separate
>build mode, rather than just modifying my own CXX_FLAGS locally, because I
>regularly use Release, Debug and RelwithDebugInfo builds. I do not want to
>have to rebuild all of VXL 2 or 3 times a day.
>
>I would not object if anyone added the facility in CMake to disable the two
>non-standard build modes (MinSizeRel and RelwithDebInfo) since these may be
>confusing to people who have just seen the standard Debug and Release modes.
>
>Finally in response to your particular problems
>1. Re the build error..
>Blame microsoft for deciding to require specification of the Standard C and
>C++ libraries at compile time (rather than link time)
>\MD specifies using the multithread supporting, non-debug DLL standard
>library. \MDd the multithread supporting, debug DLL standard library. You
>are linking with an external library that was build one of these ways, and
>you code is building in another.
>
>2. Re the run-time error
>The real distinction is between the Debug mode build on one hand and the
>RelwithDebInfo, and Release mode builds on the other.
>If it crashes in the Debug mode, but not in the Release/RelwithDebInfo
>modes, then ther is almost certainly a problem with your code. It could be
>that the oprimised version is not doing as much error checking and is
>happily ignoring the problem, or the the re-arrangement of the code and data
>in the optimised version means that a wayward pointer write is damaging a
>less critical area of memory.
>
>Regards,
>Ian.