[Bug c++/66888] New: Compiler accepting ill-formed program trying to define a struct via using-declaration

[anders.granlund.0 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66888

            Bug ID: 66888
           Summary: Compiler accepting ill-formed program trying to define
                    a struct via using-declaration
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: anders.granlund.0 at gmail dot com
  Target Milestone: ---

Created attachment 35990
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35990&action=edit
prog.cc used in the command line

The attached program is ill-formed according to the c++ standard.

This by the following clauses in the c++ standard:

* [class]p11 ( http://eel.is/c++draft/class#11 ):
Note especially the sentence "i.e., not merely inherited or introduced by a
using-declaration"

* [dcl.meaning]p1 ( http://eel.is/c++draft/dcl.meaning#1 ):
Not especially the sentence "the member shall not merely have been introduced
by a using-declaration in the scope of the class or namespace nominated by the
nested-name-specifier of the declarator-id."

When compiling with the following command line no error message is given:

gcc prog.cc

The expected behaviour is to get an error message since the program is
ill-formed.

Output from gcc -v is:

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.2-19ubuntu1'
--with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap
--enable-plugin --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --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 4.8.2 (Ubuntu 4.8.2-19ubuntu1)