[R-pkg-devel] C++17

[Uwe Ligges]

On 31.07.2021 04:15, Tim Keitt wrote:
> Kind of figured that out looking around on github. I added a config
> (borrowed from one of your repos) to test for CXX17. I'm not sure its quite
> working for me yet but I will figure it out. A couple of questions:
> 
> 1) I had C++17 in the system requirements in the description file but might
> remove it as I hope to make it check without CXX17. Does that have any
> impact on installation or is it only informative/notification?


Well, there is no platform indepednet code for dealing with that field, 
but some parts may be scripted on parts of CRAN.



> 2) If we need to adjust a package currently on CRAN owing to platform
> errors, should we keep the version the same or submit with a version bump?

Any changes in new submissions need a new version number.

Best,
Uwe Ligges




> Thanks.
> 
> THK
> 
> On Fri, Jul 30, 2021 at 2:06 PM Dirk Eddelbuettel <edd using debian.org> wrote:
> 
>>
>> Section 2.7.3 'C++ Support' of the R Admin manual says, "C++ is not used
>> by R
>> itself, but support is provided ...".  This is all stored from when R
>> itself
>> is configure (prior to compiling) and override-able in package
>> configuration
>> (Section 2.7.3 covers that) but as that in other places _it all depends on
>> what the user has installed in terms of C++ compilers_.
>>
>> So packages need to test. R 4.1.0 ensure that _if_ C++ is present it is at
>> least C++11, R 4.2.0 (aka r-devel now) is currently set to roll this to
>> C++14.  Which is ... actually rather nice and way better than what had
>> only a
>> few short years ago. But local system may still need to look after their
>> local compilers.  I still get bug reports from folks "blessed" with a
>> particularl Linux distro that seems to persist long enough so that people
>> aren't even yet at g++ 4.8 or 4.9 (though that environment has workarounds
>> too). Similarly even when R 4.2.0 comes our there will still be people
>> trying
>> to build our packages on R 3.6.* or R 3.5.*. Such is life.
>>
>> So in short, for my money, _assuming_ C++17 is present is still a wee bit
>> far
>> out. Test for it, enjoy it when it is present and deal with it if not.
>>
>> Dirk
>>
>> --
>> https://dirk.eddelbuettel.com | @eddelbuettel | edd using debian.org
>>
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