[R-pkg-devel] Rcpp with clang++ -stdlib=libc++ ?

Hi Jens,

| I can compile a package under clang++ with -stdlib=libstdc++, but with -stdlib=libc++ I get
| 
| "
| In file included from /home/jo/R/x86_64-pc-linux-gnu-library/4.0/Rcpp/include/Rcpp/r/headers.h:67:
| /home/jo/R/x86_64-pc-linux-gnu-library/4.0/Rcpp/include/Rcpp/platform/compiler.h:100:10: fatal error: 'cmath' file not found
| #include <cmath>
| ???????? ^~~~~~~
| 1 error generated.
| "
| 
| Is there any howto for using Rcpp with -stdlib=libc++ ?

That has zero to do with Rcpp.  You are lacking a C++ library header when
switching the C++ standard library along with clang. Nothing that Rcpp ships,
or governs, or selects.  

I am forgetting the fine details here (and someone may hopefully fill in
fuller details) but in short, "that is just the way it is".  I think we
simply pivot back to the g++ standard C++ library even when using clang++.

Cheers from Chicago,  Dirk

| Greetings from Munich
| 
| Jens Oehlschl?gel
| 
| ?
| P.S.
| 
| Package Makevars
| CXX_STD = CXX17
| PKG_CXXFLAGS=-O3 -march=native -pthread
| PKG_LIBS=-latomic -pthread
| 
| ~.R/Makevars
| CXX17 = clang++ -stdlib=libc++
| CXX17FLAGS = -fstack-protector-strong -D_FORTIFY_SOURCE=2 -g $(LTO)
| CXX17STD = -std=c++17
| 
| > packageVersion("Rcpp")
| [1] ?1.0.5?
| 
| > version
| ?????????????? _??????????????????????????
| platform?????? x86_64-pc-linux-gnu????????
| arch?????????? x86_64?????????????????????
| os???????????? linux-gnu??????????????????
| system???????? x86_64, linux-gnu??????????
| status????????????????????????????????????
| major????????? 4??????????????????????????
| minor????????? 0.2????????????????????????
| year?????????? 2020???????????????????????
| month????????? 06?????????????????????????
| day??????????? 22?????????????????????????
| svn rev??????? 78730??????????????????????
| language?????? R??????????????????????????
| version.string R version 4.0.2 (2020-06-22)
| nickname?????? Taking Off Again
| 
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https://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org