Bug 66888

Summary: Compiler accepting ill-formed program trying to define a struct via using-declaration
Product: gcc Reporter: Anders Granlund <anders.granlund.0>
Component: c++Assignee: Not yet assigned to anyone <unassigned>
Status: RESOLVED DUPLICATE    
Severity: normal CC: webrown.cpp
Priority: P3    
Version: unknown   
Target Milestone: ---   
See Also: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66934
Host: Target:
Build: Known to work:
Known to fail: Last reconfirmed:
Attachments: prog.cc used in the command line

Description Anders Granlund 2015-07-15 21:13:44 UTC 
Created attachment 35990 [details]
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)
Comment 1 Jonathan Wakely 2015-07-16 00:02:26 UTC 
Related to PR66879 (maybe a dup)
Comment 2 Anders Granlund 2015-07-19 00:58:47 UTC 
This bug seems to be more general than struct definitions. It also exists for variable declarations like this:

  namespace X { extern int i; }

  namespace N { using X::i; }

  int N::i = 1;

  int main() {}

The above program is ill-formed by [dcl.meaning]p1, but no error message is given.
Comment 3 Anders Granlund 2015-07-27 00:38:44 UTC 
I'm moving this into 66879 since it is very similar.

*** This bug has been marked as a duplicate of bug 66879 ***