addressof using operator& on Ubuntu's gcc-4.7 in C++11 mode

[danieljames]

I'm getting ‘operator&’ not defined compile errors from addressof on Ubuntu's GCC 4.7.4. We don't have any test runners using 4.7.4, so I guess this is specific to the exact version. Core from Boost 1.63.0 doesn't have this error.

Here's the first error:

$ "g++-4.7" "--std=c++0x" -I ../../../ addressof_test.cpp 2>&1 > addressof.output
In file included from ../../../boost/utility/addressof.hpp:15:0,
                 from addressof_test.cpp:11:
../../../boost/core/addressof.hpp: In instantiation of ‘constexpr const bool boost::detail::addressof_is_constexpr<char>::value’:
../../../boost/core/addressof.hpp:247:1:   required by substitution of ‘template<class T> constexpr typename boost::detail::addressof_if<boost::detail::addressof_is_constexpr<T>::value, T>::type boost::detail::addressof(T&) [with T = char]’
../../../boost/core/addressof.hpp:258:31:   required from ‘constexpr T* boost::addressof(T&) [with T = char]’
addressof_test.cpp:30:5:   required from ‘void scalar_test(T*) [with T = char]’
addressof_test.cpp:83:23:   required from here
../../../boost/core/addressof.hpp:225:44: error: ‘operator&’ not defined

I've uploaded the full output from boost build to addressof-error.txt. My command line was:

$ b2 gcc-4.7std11 -q > addressof-error.txt

The relevant configuration from my user-config.jam:

using gcc : 4.7std11 : g++-4.7 --std=c++11 ;

And gcc's version details:

$ g++-4.7 --version
g++-4.7 (Ubuntu/Linaro 4.7.4-3ubuntu12) 4.7.4
Copyright © 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Lastique]

I can't reproduce this in develop, master or 1.64 (from .tar.bz2 package) on Kubuntu 17.04, gcc:

g++-4.7 -v
Using built-in specs.
COLLECT_GCC=g++-4.7
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.7/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro 4.7.4-3ubuntu12' --with-bugurl=file:///usr/share/doc/gcc-4.7/README.Bugs --enable-languages=c,c++,go,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.7 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.7 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --enable-objc-gc --with-cloog --enable-cloog-backend=ppl --disable-cloog-version-check --disable-ppl-version-check --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.7.4 (Ubuntu/Linaro 4.7.4-3ubuntu12)

Looks like the compiler version is the same.

I remember we had similar errors on gcc 4.7 in an earlier version of addressof, but these were fixed before the code was merged to master. Are you sure you're using a clean and up to date source tree?

[Lastique]

Please, verify that your boost/config/compiler/gcc.hpp contains #define BOOST_NO_CXX11_SFINAE_EXPR for gcc 4.7 (line 256 in 1.64). That macro, when defined, should disable constexpr addressof, which gives the error in your log.

[pdimov]

We also have g++ 4.7 in Travis.

[glenfe]

I also tested with g++ 4.7 on Ubuntu 17.04 (sudo apt install g++4.7) which was 4.7.4, without any issues.

[danieljames]

I'll check when I get home later. I'm pretty sure I tested with the tags 1.63.0 and 1.64.0 of core when I got this, but I didn't check config.

[Lastique]

That piece of code relies on a new feature of Boost.Config, so make sure to update it as well.

[danieljames]

Config was out of date.