Trevor Saunders <tbsau...@tbsaunde.org> writes: > On Wed, Aug 12, 2015 at 01:03:36PM -0600, Jeff Law wrote: >> On 08/12/2015 12:57 PM, Richard Sandiford wrote: >> >Jeff Law <l...@redhat.com> writes: >> >>On 08/10/2015 06:05 AM, tbsaunde+...@tbsaunde.org wrote: >> >>>From: Trevor Saunders <tbsaunde+...@tbsaunde.org> >> >>> >> >>>Hi, >> >>> >> >>>In many places gcc puts classes in the anon namespace so the >> >>> compiler can tell >> >>>they do not get inheritted from to enable better devirtualization. >> >>>However >> >>>debugging code in the anon namespace can be a pain, and the same >> >>> thing can be >> >>>accomplished more directly by marking the classes as final. When >> >>>bootstrapping >> >>>stage 3 should always be built in C++14 mode now, and of course >> >>> will always be >> >>>newer than gcc 4.7, so these classes will always be marked as final there. >> >>>AIUI cross compilers are supposed to be built with recent gcc, >> >>> which I would >> >>>tend to think implies newer than 4.7, so they should also be built >> >>> with these >> >>>classes marked as final. I believe that means in all important cases >> >>>this works just as well as the anon namespace. >> >>> >> >>>bootstrapped + regtested on x86_64-linux-gnu, ok? >> >>> >> >>>Trev >> >>> >> >>> >> >>>gcc/ChangeLog: >> >>> >> >>>2015-08-10 Trevor Saunders <tbsau...@tbsaunde.org> >> >>> >> >>> * compare-elim.c, dce.c, dse.c, gimple-ssa-isolate-paths.c, >> >>> gimple-ssa-strength-reduction.c, graphite.c, init-regs.c, >> >>> ipa-pure-const.c, ipa-visibility.c, ipa.c, mode-switching.c, >> >>> omp-low.c, reorg.c, sanopt.c, trans-mem.c, tree-eh.c, >> >>> tree-if-conv.c, tree-ssa-copyrename.c, tree-ssa-dce.c, >> >>> tree-ssa-dom.c, tree-ssa-dse.c, tree-ssa-forwprop.c, >> >>> tree-ssa-sink.c, tree-ssanames.c, tree-stdarg.c, tree-tailcall.c, >> >>> tree-vect-generic.c, tree.c, ubsan.c, var-tracking.c, >> >>> vtable-verify.c, web.c: Use GCC_FINAL instead of the anonymous >> >>>namespace. >> >>OK. >> > >> >I was hoping someone else was going to speak up since I seem >> >to have been posting a few negative messages recently, but I think >> >this is really a step in the wrong direction. I think the code >> >was using anonymous namespaces in exactly the way they were > > are they actually all that common? I think gcc is the only C++ with > which I'm familiar that uses them much.
Yeah, fair question. I suppose working on a codebase with anonymous namespaces day-in day-out doesn't make them more common than working on the codebase for one day :-) Even if it felt that way at the time... But an internal codebase at a previous job used them. LLVM also used them quite a bit when I was looking after the SystemZ port (I assume still does). Thanks, Richard
