[Bug c++/60686] New: message "=?UTF-8?Q?=20only=20declarations=20of=20constructors=20can=20be=20=E2=80=98explicit=E2=80=99=20?=" now conflicting with C++11

[a.gronchi at nextworks dot it]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60686

            Bug ID: 60686
           Summary: message " only declarations of constructors can be
                    ‘explicit’ " now conflicting with C++11
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: a.gronchi at nextworks dot it

The error message:

error: only declarations of constructors can be ‘explicit’

today conflicts with C++11, which also allows conversion operators to be marked
explicit.

Sample code:

struct A {
        explicit operator int() const;
};
explicit inline A::operator int() const { return 1; }


Here the second occurrence of the "explicit" keyword is illegal, but the
reported error message leads one to think about GCC lacking support for
explicit conversion operators.


Reproducible with GCC 4.8.2:

Using built-in specs.
COLLECT_GCC=g++-4.8.2
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.8.2/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-4.8.2-r1/work/gcc-4.8.2/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.8.2
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.2
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.2/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.8.2/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.2/include/g++-v4
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.8.2/python
--enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt
--disable-werror --with-system-zlib --enable-nls --without-included-gettext
--enable-checking=release --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo 4.8.2-r1 p1.4-ssptest, pie-0.5.9-ssptest'
--enable-libstdcxx-time --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-multilib
--with-multilib-list=m32,m64 --disable-altivec --disable-fixed-point
--enable-targets=all --disable-libgcj --enable-libgomp --disable-libmudflap
--disable-libssp --enable-lto --without-cloog
Thread model: posix
gcc version 4.8.2 (Gentoo 4.8.2-r1 p1.4-ssptest, pie-0.5.9-ssptest)