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. :)