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

3 messages · Dan Zigmond, David Kepplinger

Original
Dan Zigmond
# 
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

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--------------------------
Dan Zigmond
djz at shmonk.com
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 at shmonk.com> wrote:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Dan Zigmond
    

    

      
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Thank you! That's very helpful.

     Dan

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--------------------------
Dan Zigmond
djz at shmonk.com



On Sat, Nov 21, 2020 at 5:14 PM David Kepplinger <david.kepplinger at gmail.com>
wrote: