[R-pkg-devel] warning: binary constants are a C++14 feature or GCC extension

[David Kepplinger]

Dear Dan,

As the warning says, the binary notation you use is only valid with
C++14 and onwards. You can either add SystemRequirements: C++14 to
your DESCRIPTION file, or use decimal (or hex) notation.

In my opinion it's even better to name your constants to convey their
meaning to the reader of the code. Then it wouldn't be a big issue if
you use binary, decimal, or hex notation.

Best,
David

On Sat, Nov 21, 2020 at 4:59 PM Dan Zigmond <djz using shmonk.com> wrote:
>
> Hi, all. In re-submitting a package to CRAN, I'm getting the following
> warnings in the Debian pre-test:
>
> Found the following significant warnings:
>   sort.cpp:12:28: warning: binary constants are a C++14 feature or GCC extension
>   sort.cpp:12:43: warning: binary constants are a C++14 feature or GCC extension
>
> I added some C++ code to speed up the package and the warnings refer to
> this line of C++:
>
>    while ((s[p + length] & 0b11000000) == 0b10000000) {
>
> The line has to do with parsing UTF-8 strings by figuring out how many
> bytes are used in each character. Is the 0b... notation not allowed in
> CRAN? I could substitute decimal constants, but that will be a bit more
> obtuse. The other platforms seems to allow this; only the Debian check
> failed.
>
>      Dan
>
> .
> --------------------------
> Dan Zigmond
> djz using shmonk.com
>
>         [[alternative HTML version deleted]]
>
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-- 
David Kepplinger, PhD
https://www.dkepplinger.org