C++14 Support

[hnefatl]

I'm trying to use a library which requires C++14 compiler support, and I've been unable to get x86_64-rumprun-netbsd-g++ to cooperate.

As I couldn't find any references on how to do this, my approach has been to compile rumprun using g++ 5.4.0, which does support C++14. The resulting x86_64-rumprun-netbsd-g++ reports the right version:

> x86_64-rumprun-netbsd-g++ --version
g++ (GCC) 5.4.0

But compiling a simple program using a C++14 feature like std::cbegin:

#include <vector>

int main()
{
    std::vector<int> a { 1, 2, 3 };
    std::vector<int>::const_iterator i = std::cbegin(a);
}

...fails with x86_64-rumprun-netbsd-g++:

> x86_64-rumprun-netbsd-g++ -std=c++14 test.cpp
test.cpp: In function ‘int main(int, char**)’:
test.cpp:6:42: error: ‘cbegin’ is not a member of ‘std’

...but works with g++ 5.4.0:

> g++5 -std=c++14 test.cpp

Is what I'm trying to achieve possible? If so, any advice on what mistake I'm making?

If relevant, the g++ I'm using has been built from source, so isn't the system default. I built rumprun using:

export CC=gcc5
export CXX=g++5
./build-rr.sh -j 4 hw -- -r -j 4

[hnefatl]

Oh, just realised that x86_64-rumprun-netbsd-g++ is just a wrapper script. Don't know how I didn't notice that sooner.

In any case, looks like it passes through to $prefix/libexec/rumprun-x86_64-hw/x86_64--netbsd-c++ (as I built for hw). Calling this file like:

> x86_64--netbsd-c++ -std=c++14 test.cpp

...compiles fine (and even runs correctly on my x86_64 Debian Jessie laptop). So I guess somewhere in the x86_64-rumprun-netbsd-g++ script a parameter's not getting passed through correctly.

Edit: I've noticed that the x86_64-rumprun-netbsd-g++ script invokes --sysroot on the compiler, which I thought could be the issue if the new root didn't have C++14 header files - but it does have them (on my install, at least), so that's not the issue.

Edit 2: If the x86_64-rumprun-netbsd-g++ script is modified to print out the command line it's going to exec before it does, -std=c++14 is there. Here's what mine looked like (newlines added for presentation):

<rumprun path>./rumprun/libexec/rumprun-x86_64-hw/x86_64--netbsd-c++
-mno-red-zone
-no-integrated-cpp
--sysroot <rumprun path>./rumprun/rumprun-x86_64
-specs=<rumprun path>./rumprun/rumprun-x86_64/lib/specs-compile_or_ferment
-Wl,-r -Wl,-u,main
-std=c++14 test.cpp
<rumprun path>./rumprun/rumprun-x86_64/share/x86_64-rumprun-netbsd-recipe.s
-lc++ -lunwind

So I suppose it's actually an issue of conflicting arguments somewhere.

Edit 3: Okay now I'm confused - I dug around some more, and none of the switches seem like they could conflict with -std=c++14 except the -spec one, which overrides the default compiler spec with a new one. In my spec file, the relevant lines seem to be:

*cpp_options:
-nostdinc -isystem <rumprun path>./rumprun/rumprun-x86_64/include %{,c++:%{!std=*:-std=c++11}} %{,c++:-isystem <rumprun path>./rumprun/rumprun-x86_64/include/c++} %(old_cpp_options) -D__NetBSD__  -Ulinux -U__linux -U__linux__ -U__gnu_linux__ -D__RUMPRUN__

...

*cc1plus:
%{!std=*:-std=c++11}

...which if my understanding of these docs is correct, should be doing something like "if the std switch isn't given, then add the switch -std=c++11". This seems like it shouldn't conflict, then, as if I specify no std switch it doesn't compile either. I have tried changing both occurrences to c++14 and running the x86_64-rumprun-netbsd-g++ script with and without a std switch, but nothing different happens.

[hnefatl]

Okay, I've checked through most of the flags now and I am completely confused. It looks like x86_64-rumprun-netbsd-g++ is working with C++14, it's just unable to find the right header.

Manually peeking inside <rumprun path>/rumprun/rumprun-x86_64/include/c++/iterator shows all the C++14 and even some C++17 function declarations, as expected. As evident from the below verbose output dump from x86_64-rumprun-netbsd-g++ -v -std=c++14 test.cpp it's even looking in the right places.

Using #include <<rumprun path>/rumprun/rumprun-x86_64/include/c++/iterator> didn't work either, so... yeah. I'm stumped.

{rumprun path}/rumprun/libexec/rumprun-x86_64-hw/x86_64--netbsd-c++ -mno-red-zone -no-integrated-cpp --sysroot {rumprun path}/rumprun/rumprun-x86_64 -specs={rumprun path}/rumprun/rumprun-x86_64/lib/specs-compile_or_ferment -Wl,-r -Wl,-u,main -v -std=c++14 test.cpp {rumprun path}/rumprun/rumprun-x86_64/share/x86_64-rumprun-netbsd-recipe.s -lc++ -lunwind
Using built-in specs.
Reading specs from {rumprun path}/rumprun/rumprun-x86_64/lib/specs-compile_or_ferment
rename spec cpp_options to old_cpp_options
rename spec cc1_options to old_cc1_options
rename spec link_libgcc to old_link_libgcc
rename spec libgcc to old_libgcc
COLLECT_GCC={gcc5 path}/bin/g++
COLLECT_LTO_WRAPPER={gcc5 path}libexec/gcc/x86_64-unknown-linux-gnu/5.4.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --prefix={gcc path} --enable-languages=c,c++ --disable-multilib
Thread model: posix
gcc version 5.4.0 (GCC) 
COLLECT_GCC_OPTIONS='-mno-red-zone' '-no-integrated-cpp' '-specs={rumprun path}/rumprun/rumprun-x86_64/lib/specs-compile_or_ferment' '-v' '-std=c++14' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 {gcc5 path}libexec/gcc/x86_64-unknown-linux-gnu/5.4.0/cc1plus -E -nostdinc -isystem {rumprun path}/rumprun/rumprun-x86_64/include -isystem {rumprun path}/rumprun/rumprun-x86_64/include/c++ -quiet -v -imultiarch x86_64-linux-gnu -isysroot {rumprun path}/rumprun/rumprun-x86_64 -D_GNU_SOURCE test.cpp -mno-red-zone -mtune=generic -march=x86-64 -std=c++14 -D__NetBSD__ -Ulinux -U__linux -U__linux__ -U__gnu_linux__ -D__RUMPRUN__ -o /tmp/ccoaKcYx.ii
#include "..." search starts here:
#include <...> search starts here:
 {rumprun path}/rumprun/rumprun-x86_64/include
 {rumprun path}/rumprun/rumprun-x86_64/include/c++
End of search list.
COLLECT_GCC_OPTIONS='-mno-red-zone' '-no-integrated-cpp' '-specs={rumprun path}/rumprun/rumprun-x86_64/lib/specs-compile_or_ferment' '-v' '-std=c++14' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 {gcc5 path}libexec/gcc/x86_64-unknown-linux-gnu/5.4.0/cc1plus -fpreprocessed /tmp/ccoaKcYx.ii -quiet -dumpbase test.cpp -mno-red-zone -mtune=generic -march=x86-64 -auxbase test -std=c++14 -version -mno-red-zone -fno-stack-protector -fno-builtin-sin -fno-builtin-sinf -fno-builtin-cos -fno-builtin-cosf -o /tmp/ccwEyqmR.s
GNU C++14 (GCC) version 5.4.0 (x86_64-unknown-linux-gnu)
	compiled by GNU C version 5.4.0, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++14 (GCC) version 5.4.0 (x86_64-unknown-linux-gnu)
	compiled by GNU C version 5.4.0, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: ad108975c825c71463335b0918a936e6
test.cpp: In function ‘int main(int, char**)’:
test.cpp:10:42: error: ‘cbegin’ is not a member of ‘std’
     std::vector::const_iterator i = std::cbegin(a);
                                          ^
COLLECT_GCC_OPTIONS='-mno-red-zone' '-no-integrated-cpp' '-specs={rumprun path}/rumprun/rumprun-x86_64/lib/specs-compile_or_ferment' '-v' '-std=c++14' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 as -v --64 -o /tmp/cc3BXHYb.o {rumprun path}/rumprun/rumprun-x86_64/share/x86_64-rumprun-netbsd-recipe.s
GNU assembler version 2.28 (x86_64-linux-gnu) using BFD version (GNU Binutils for Debian) 2.28

[oberstet]

I am also interested in gcc with c++ 14 (or at least 11) .. actually I need Boost/ASIO and https://github.com/crossbario/autobahn-cpp, which is pretty heavy on templates, std::future etc