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Converting GCC to C++Converting GCC to C++Posted Jun 18, 2008 17:20 UTC (Wed) by madscientist (subscriber, #16861)Parent article: Converting GCC to C++
I don't have a problem with this as a concept, but IMO Ian doesn't fully confront the most difficult issue (IMO): bootstrapping. Although I can see where it's painful for the GCC maintainers, it's very, very nice to not need anything fancier than a simple C compiler in order to build GCC itself. On the other hand, maybe this effort will convince the GCC folks to come to grips with cross-compiled/encapsulated C++ and the issues it has (just for example, we have a -static-libgcc flag, but no -static-libstdc++ ...)
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Converting GCC to C++ Posted Jun 18, 2008 21:56 UTC (Wed) by linuxrocks123 (guest, #34648) [Link] If my understanding is correct, GCC uses GCC language extensions all over the place anyway, and doesn't support being bootstrapped by anything other than GCC itself. Therefore, I don't think they'd be losing much portability with regard to bootstrapping; they're not portable as it is.
Converting GCC to C++ Posted Jun 18, 2008 22:11 UTC (Wed) by madscientist (subscriber, #16861) [Link] I don't believe this is true. Or rather, the build for GCC today builds a version of the C compiler only, called "xgcc", and that bootstrapping compiler is used to build all the other compilers in the collection (including the final "gcc" C compiler). However, as far as I'm aware you do NOT need GCC to build the bootstrapping compiler. It appears that this proposal would change the bootstrapping compiler to be C++ (xg++ or similar) instead of C--and that implies a LOT more about the properties of the host system. Either you have to have a very capable C++ compiler already installed on the system, or you have to restrict your use of C++ in at least the bootstrapping section of GCC to a generic subset. Even though Ian says he wants to use a sensible subset of C++, the kinds of things he wants to use (templates for example) are the kinds of things that have only relatively recently been implemented in a sane manner among a majority of compilers. I guess the "initial bringup" could be something like, build GCC 4.3 (or whatever the last version written in C was) for your target, then use that to build GCC 5.0 written in C++. Once you have that you can use it to build subsequent versions. Annoying but you only have to do it once. That restricts you to using whatever C++ support appears in GCC 4.3 (or whatever) but that seems like it should be pretty safe. Still, I think there's more trouble here than Ian's slides indicate.
Converting GCC to C++ Posted Jun 18, 2008 22:19 UTC (Wed) by stevenb (guest, #11536) [Link] Bootstrapping is *by* *definition* a compiler compiling itself. But the first step (in this case: building a gcc to build gcc, the so-called stage0 compiler) can be done with any ISO C90 compiler. So bootstrapping really doesn't limit portability.
Converting GCC to C++ Posted Jun 19, 2008 0:38 UTC (Thu) by gdt (subscriber, #6284) [Link] I don't have a problem with this as a concept, but IMO Ian doesn't fully confront the most difficult issue (IMO): bootstrapping. If it is such a difficult problem then I suppose a side-effect of the proposal will be to change the strategy for bringing up GCC on a new platform from bootstrapping to cross-compiling.
Converting GCC to C++ Posted Jun 19, 2008 1:32 UTC (Thu) by vomlehn (subscriber, #45588) [Link] It could be a good thing if the strategy changes from bootstrapping to cross-compiling, as it implies more use of cross-compiling. Such a change seems likely to drive improvements to cross-compiling, a subject near and dear to many in the embedded world.
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