Re: [EXTERNAL] Re: GCC selftest improvements
Thanks, Dave. We will work on the legal papers with FSF. -- Gaby From: David Malcolm Sent: Tuesday, February 25, 2020 2:10:59 PM To: Modi Mo ; l...@redhat.com ; Nicholas Krause ; Eric Gallager ; Pedro Alves Cc: Gabriel Dos Reis ; Andrew Dean ; gcc@gcc.gnu.org ; r...@cebitec.uni-bielefeld.de ; mikest...@comcast.net ; ja...@redhat.com ; Jonathan Wakely ; Richard Biener Subject: Re: [EXTERNAL] Re: GCC selftest improvements On Tue, 2020-02-25 at 19:58 +, Modi Mo wrote: > > On 2/12/20 8:53 PM, David Malcolm wrote: > > The patch will need an update to the docs; search for > > "Tools/packages necessary for building GCC" in > > gcc/doc/install.texi, which currently has some paragraphs labelled: > >@item ISO C++98 compiler > > that will need changing. > > Added this change in the attached patch. Thanks Modi. Before looking at the updated patch in detail, we ought to also address the legal prerequisites for contributing. Does your employer have legal paperwork in place with the FSF for such contributions? See: https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fcontribute.html%23legal&data=02%7C01%7Cgdr%40microsoft.com%7C78624c908d354c815f9d08d7ba3fa1f6%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63718265478884&sdata=8GiCH%2FijVByqeO6e9qdRw3C09o0Suh62Gf8kq2HYe%2B4%3D&reserved=0 I'm not sure what the threshold is for a contribution to be regarded as "significant", but it seems that we ought to be fastidious here, given historical attitudes between Microsoft and the FLOSS community. (I'm not speaking on behalf of anyone other than myself here, as a GCC maintainer, and I don't mean for this to come across as personal) Thanks Dave
RE: GCC selftest improvements
[Andrew] | > GCC has some rather unique requirements, in that we support a great many | > build configurations, some of which are rather primitive - for example, | > requiring just C++98 with exceptions disabled, in that we want to be able to | be | > bootstrappable on relatively "ancient" configurations. | > IIRC auto-registration of tests requires that the build configuration have a | > sufficiently sane implementation of C++ - having globals with non-trivial | ctors | > tends to be problematic when dealing with early implementations of C++. | | Is C++98 the limit of what we can use in GCC? If so, that immediately | eliminates Catchv1 (C++03), Catch2 (C++11+) and GTest (C++11) C++98 was what Diego, Lawrence, Benjamin, Ian, and myself could agreed to back in 2011-2012 when C++11 got just out as a C++ standard, so we couldn't pick C++11 as we didn't have enough G++ out there to count on. I would expect the situation to have drastically changed - with very handy and popular features such as 'constexpr' (especially with the C++14 relaxation), lambdas and range-for. Jason, Jonathan - is the situation on the terrain really that dire that C++11 (or C++14) isn't at all available for platforms that GCC is bootstrapped from? -- Gaby
RE: GCC selftest improvements
| -Original Message- | From: Jeff Law | Sent: Monday, October 28, 2019 12:44 PM | To: Richard Biener ; gcc@gcc.gnu.org; | Gabriel Dos Reis ; Andrew Dean | ; David Malcolm ; | r...@cebitec.uni-bielefeld.de; mikest...@comcast.net; | ja...@redhat.com; Jonathan Wakely | Subject: Re: GCC selftest improvements | | On 10/28/19 1:42 PM, Richard Biener wrote: | >> | >> I'd really like to see us move to C++11 or beyond. Sadly, I don't | >> think | >> we have any good mechanism for making this kind of technical decision | >> when there isn't consensus. | > | > Well, we just do it? | For some reason I thought you were against such a change. Was I wrong? I suspect Andrew would be happy to contribute patch and any follow up. -- Gaby
RE: GCC selftest improvements
| -Original Message- | From: Andrew Pinski | Sent: Monday, October 28, 2019 2:52 PM | To: Jakub Jelinek | Cc: Jeff Law ; Segher Boessenkool | ; Gabriel Dos Reis ; | Andrew Dean ; David Malcolm | ; gcc@gcc.gnu.org; r...@cebitec.uni-bielefeld.de; | mikest...@comcast.net; ja...@redhat.com; Jonathan Wakely | | Subject: Re: GCC selftest improvements | | On Mon, Oct 28, 2019 at 2:47 PM Jakub Jelinek wrote: | > | > On Mon, Oct 28, 2019 at 03:41:13PM -0600, Jeff Law wrote: | > > On 10/28/19 2:27 PM, Segher Boessenkool wrote: | > > > On Mon, Oct 28, 2019 at 01:40:03PM -0600, Jeff Law wrote: | > > >> On 10/25/19 6:01 PM, Gabriel Dos Reis wrote: | > > >>> Jason, Jonathan - is the situation on the terrain really that dire that | C++11 (or C++14) isn't at all available for platforms that GCC is bootstrapped | from? | > > >> The argument that I'd make is that's relatively uncommon (I know, I | know | > > >> AIX) that bootstrapping in those environments may well require first | > > >> building something like gcc-9. | > > >> | > > >> I'd really like to see us move to C++11 or beyond. Sadly, I don't think | > > >> we have any good mechanism for making this kind of technical | decision | > > >> when there isn't consensus. | > > > | > > > Which GCC version will be required to work as bootstrap compiler? Will | > > > 4.8.5 be enough? | > > I'd say gcc-9. What would we gain by making it 4.8 or anything else | > > that old? | > | > That is not a good idea, it will make it much harder to build gcc because | > not everybody has gcc-9 built as a system compiler. | > The previous minimum requirement of 4.1 is perhaps too old now that 4.8 | is | > something we could require and gain through that C++11 support, but we | > shouldn't follow Rust with "you can only build it with 6 weeks old previous | > release and nothing else". | > As discussed earlier, we gain most through C++11 support, there is no need | > to jump to C++17 or C++20 as requirement. | | Just a quick note. | RHEL/CentOS 7 uses GCC 4.8 as the system compiler. Requiring a new | compiler to compile GCC 10 will not work for me. | I normally bootstrap GCC 10 and then build a GCC 10 cross compiler. | Having to have an extra compiler inbetween is problematic for me. | | Thanks, | Andrew I would think C++14 gives you a good compromise, as you have access to key C++11 functionalities with a less crippled constexpr support. -- Gaby
