On 28/09/2020 12:44, Andreas Kersting wrote:
Hi,
what is the correct way to specify a C standard in a package's Makevars file?
Building a package with e.g. PKG_CFLAGS = -std=gnu11 does work but R CMD check
issues a warning:
for some unstated value of 'work' ...
* checking compilation flags in Makevars ... WARNING
Non-portable flags in variable 'PKG_CFLAGS':
-std=gnu11
(Same for -std=c11.)
Thanks! Regards,
Andreas Kersting
Those flags are not portable, as 'check' correctly says. Furthermore,
on some platforms there may be no flag which can be added -- R documents
that 'CC' specifies a C99 compiler, and that or CC+CFLAGS are likely to
specify flags which are incompatible with -std=c11 (true on Solaris
where -xc99 is used).
So, like all such overrides (see 'Writing R Extensions') you need to
write a configure script (preferably using autoconf) to
- select an appropriate C compiler+flags
- substitute them into src/Makefile.in
For the new features I have used in C11, all known compilers make them
available in C99 mode and a configure script could be used to test for
their presence (as R itself does). That is, it is rare to actually need
to specify C11 mode.
--
Brian D. Ripley, rip...@stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford
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