[boost] [Boost-build] Turn on _GLIBCXX_DEBUG with <runtime-debugging>on (was: Trivial issues have been neglected.)

Subject: [boost] [Boost-build] Turn on _GLIBCXX_DEBUG with <runtime-debugging>on (was: Trivial issues have been neglected.)
From: Matthew Chambers (matt.chambers42_at_[hidden])
Date: 2012-10-25 10:56:33

I'm forwarding this from the boost-build list to get a broader perspective from boost users and 
probably also some Boost.Build users that don't monitor that list.

How many agree with Steven that for <variant>debug:
"The libraries that are built need to be ABI compatible with code that isn't compiled using 
Boost.Build."

How many would sacrifice ABI compatibility in order for <runtime-debugging>on to actually do 
something for GCC?

Thanks,
-Matt

 > (2012/10/17 0:09), Matthew Chambers wrote:
 >> On 10/15/2012 11:29 PM, Steven Watanabe wrote:
 >>> AMDG
 >>>
 >>> On 10/15/2012 07:54 PM, Kohei Takahashi wrote:
 >>>> Hi all,
 >>>>
 >>>> Can anyone handle following two issues?
 >>>>
 >>>> <runtime-debugging>on does nothing for libstdc++...
 >>>> https://svn.boost.org/trac/boost/ticket/4589
 >>>>
 >>>
 >>> This is /not/ a trivial issue.  It may be easy to do, but:
 >
 > I understood about this is not trivial issue and I changed the subject.
 >
 >
 >>> a) _GLIBCXX_DEBUG was broken last time I tried it a few years
 >>> ago.  It won't work with all versions of gcc.
 >>
 >> I've used it with 4.1.2 and it helped a lot to track down some
 >> mysterious failures.
 > I don't know about old releases but recents seem to work well for me.
 > Indeed, expects to work well and should work with all versions of gcc
 > if define it by default.
 >
 >>> b) Anything the changes the ABI of the compiled libraries needs
 >>> careful consideration and must be documented.  The libraries that
 >>> are built need to be ABI compatible with code that isn't
 >>> compiled using Boost.Build.
 >>
 >> Is it really that important that debug builds be ABI compatible
 >> between disparate builds? I think it's reasonable to EXPECT trouble
 >> when linking a debug build to precompiled libraries. That is
 >> certainly the case on Windows.
 >
 > <define> is not propagated feature, that means to trigger unexpected
 > link failure or ABI breaking. I think that using <runtime-debugging>
 > make safely rather than <define>.
 > I think it is better that provides propagated feature (as
 > <runtime-debugging> or another) for such purpose at least.
 >
 >
 >>> c) <runtime-debugging>on is part of <variant>debug, but I don't
 >>> think _GLIBCXX_DEBUG is a standard part of debug builds with
 >>> gcc.
 >>
 >> What is a "standard" debug build with gcc? Most people would
 >> probably say -g and -O0 but that doesn't provide any real debugging
 >> support.
 >>
 >> I agree it's not trivial, but having a no-op runtime-debugging
 >> feature is cringe-worthy. It's as good as admitting that GCC (or
 >> rather, libstdc++) doesn't provide any "official" runtime debugging
 >> support which is unfair.
 >>
 >> In the spirit of upcoming elections, count this as a vote for
 >> turning on _GLIBCXX_DEBUG. :)