Re: the risk of dependencies on the C++ runtime. (apologies Konstantin, your email got trapped in a spam filter; "It is in violation of Google's recommended email sender guidelines", according to GMail).
Avoiding C++ runtime dependencies is fairly straightforward in practice (e.g. a program that doesn't use *use* thread-local objects with destructors won't link against cxa_thread_atexit; similarly, -fno-exceptions and -fno-rtti and their equivalents are widely available). It's impossible of course to guarantee that FreeBSD won't ever want to switch to a (not-yet-written, afaik) compiler + ABI combo that doesn't admit a runtime-less C++, but that seems unlikely (and, if it were to happen, it would take enough years of notice and effort that porting the allocator back to C would be a small relative cost). We also test bootstrapping behavior against the libcs that we care about, so that we get some relatively good signal that everything will integrate correctly on a per-jemalloc-commit basis (we don't try to test against FreeBSD head, but I don't think that's necessarily a feasible strategy). I'm sympathetic to the costs of the added compiler required for those building libc, but weighing it against the ongoing maintenance drag on our end, it seems like a no-brainer (especially when we already come with dependencies outside of just the compiler and base build system). - David On Thu, Oct 5, 2017 at 11:59 AM, David Goldblatt <davidtgoldbl...@gmail.com> wrote: > Hi all, > > The jemalloc developers have wanted to start using C++ for a while, to > enable some targeted refactorings of code we have trouble maintaining due > to brittleness or complexity (e.g. moving thousand line macro definitions > to templates, changing the build->extract symbols->rebuild mangling scheme > for internal symbols to one using C++ namespaces). We'd been holding off > because we thought that FreeBSD base all had to compile on GCC 4.2, in > order to support some esoteric architectures. > > The other day though, I noticed that there is some C++ shipping with > FreeBSD; /usr/bin/dtc and /sbin/devd (the former claiming in the HACKING > document that C++11 is a minimum for FreeBSD 11). This, combined with the > fact that ports now points to a modern gcc, makes me think we were > incorrect, and can turn on C++ without breaking FreeBSD builds. > > Am I right? Will anything break if jemalloc needs a C++ compiler to build? > We will of course not use exceptions, RTTI, global constructors, the C++ > stdlib, or anything else that might affect C source or link compatibility. > > Thanks, > David (on behalf of the jemalloc developers > >  That being said, we don't compile or test on those architectures, and > so probably don't work there in the first place if I'm being honest. But > we'd also like to avoid making that a permanent state of affairs that can't > be changed. > _______________________________________________ email@example.com mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"