[Rd] possible bug in R's configure check for C++11 features

[Simon Urbanek]

Kasper,

I haven’t checked in depth, so just to clarify: you *are* setting CXX11=g++ so it is doing what you asked it to. Since the settings are inherited upwards, this implies that you are setting both CXX14 and CXX17 to g++. So I’m not quite sure I understand your concern.

Cheers,
Simon



> On Sep 3, 2019, at 9:02 PM, Kasper Daniel Hansen <kasperdanielhansen using gmail.com> wrote:
> 
> I am trying to compile R under a new setup, and frankly, I have had a lot
> of problems, but I think the stuff below points to a possible bug in R's
> (custom) configure checks for C++11/14/17, but not for C++98.
> 
> This is a report about R from the R-3-6 branch, with a svn checkout from
> today, revision r77135.
> 
> In my case the compiler name is x86_64-conda_cos6-linux-gnu-g++, not g++. I
> denote this in my configure call, using the CC variable. A snippet of the
> full configure is
> 
> ../${SRCDIR}/configure SHELL='/bin/bash' \
>   --prefix="${CONDA_PREFIX}/R/${R_VERSION}" \
>   CC="x86_64-conda_cos6-linux-gnu-gcc" \
>   CXX="x86_64-conda_cos6-linux-gnu-g++" \
>   F77="x86_64-conda_cos6-linux-gnu-gfortran" \
>   FC="$F77" \
>   CFLAGS="-Wall -mtune=amdfam10 -g -O2 -I${CONDA_PREFIX}/include"\
>   CXXFLAGS="-Wall -mtune=amdfam10 -g -O2 -I${CONDA_PREFIX}/include" \
>   F77FLAGS="-Wall -g -O2 -mtune=amdfam10 -I${CONDA_PREFIX}/include" \
>   CXX11="g++" \
>   CXX11STD="-std=c++11" \
>   CXX11FLAGS="-Wall -mtune=amdfam10 -g -O2 -I${CONDA_PREFIX}/include" \
>   CXX11PICFLAGS="-fPIC" \
> 
> Where $CONDA_PREFIX is given in my script.
> 
> The output in config.log is given below. Note that in the test for c++98,
> it uses the "right" CC, but in the test for c++11 it uses g++. This looks
> wrong to me:
> 
> configure:28111: checking whether x86_64-conda_cos6-linux-gnu-g++  supports
> C++98 features with -std=gnu++98
> configure:28130: x86_64-conda_cos6-linux-gnu-g++  -std=gnu++98 -c -Wall
> -mtune=amdfam10 -g -O2
> -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
> -fpic -DNDEBUG -D_FORTIFY_SOURCE=2 -O2 conftest.cp
> p >&5
> configure:28130: $? = 0
> configure:28139: result: yes
> configure:28315: checking whether g++ -std=c++11 supports C++11 features
> configure:28607: g++ -std=c++11 -c -Wall -mtune=amdfam10 -g -O2
> -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
> -fPIC -DNDEBUG -D_FORTIFY_SOURCE=2 -O2 conftest.cpp >&5
> ../R-3.6-src/configure: line 2355: g++: command not found
> configure:28607: $? = 127
> configure: failed program was:
> 
> I have similar issues (wrong CC using when compiling the test program) with
> the test for c++14, whereas the test for c++17 has empty space where the CC
> variable should be?
> 
> I can fix this issue by adding a soft link in my PATH from g++ to my
> compiler of choice. In this case configure finishes and reports that I have
> full C++17 capabilities. Weirdly, in the output, note that the C++ compiler
> is "wrong" again, despite my configure call:
> 
>  Source directory:            ../R-3.6-src
>  Installation directory:
> /jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/R/3.6
> 
>  C compiler:                  x86_64-conda_cos6-linux-gnu-gcc  -Wall
> -mtune=amdfam10 -g -O2
> -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  Fortran fixed-form compiler:
> /jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/bin/x86_64-conda_cos6-linux-gnu-gfortran
> -fno-optimize-sibling-calls -fopenmp -march=nocona -mtune=haswell
> -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2
> -ffunction-sections -pipe
> 
>  Default C++ compiler:        g++ -std=c++11   -Wall -mtune=amdfam10 -g
> -O2 -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  C++98 compiler:              x86_64-conda_cos6-linux-gnu-g++ -std=gnu++98
> -Wall -mtune=amdfam10 -g -O2
> -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  C++11 compiler:              g++ -std=c++11   -Wall -mtune=amdfam10 -g
> -O2 -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  C++14 compiler:              g++ -std=gnu++14   -Wall -mtune=amdfam10 -g
> -O2 -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  C++17 compiler:              g++ -std=gnu++17  -Wall -mtune=amdfam10 -g
> -O2 -I/jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/include
>  Fortran free-form compiler:
> /jhpce/shared/jhpce/core/conda/miniconda3-4.6.14/envs/svnR-3.6/bin/x86_64-conda_cos6-linux-gnu-gfortran
> -fno-optimize-sibling-calls
>  Obj-C compiler:
> 
> 
> 
> -- 
> Best,
> Kasper
> 
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