[Bug c++/13927] New: confusing error message on ibad redeclaration of anon union

["mec dot gnu at mindspring dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Consider this ill-formed program:

  int main ()
  {
    union { int alpha; int beta; };
    double alpha;
    return 0;
  }

This is bad because "alpha" is declared twice.

gcc HEAD says:

/berman/fsf/_today_/berman/install/target/native/gcc/gcc-HEAD-as-2.14-ld-2.14/bin/g++
-S au-3.cc
  au-3.cc: In function `int main()':
  au-3.cc:4: error: `double alpha' redeclared as different kind of symbol
  au-3.cc:3: error: previous declaration of `#`alias_decl' not supported by
dump_decl#<declaration error>'
  au-3.cc:4: error: declaration of `double alpha'
  au-3.cc:3: error: conflicts with previous declaration `#`alias_decl' not
supported by dump_decl#<declaration error>'

This doesn't bother me because the line numbers do point to the right place so
that people can get work done.  But it might be nicer if gcc could print a
better error message.

That is, I wouldn't mind a WONTFIX on this one, if fixing it would make the
compiler less elegant.  But I suspect that there is code which doesn't know
about these strange types created by anon union variables so it might be good to
fix this.

For comparison, gcc 3.3.2 prints:

au-3.cc: In function `int main()':
au-3.cc:4: error: conflicting types for `double alpha'
au-3.cc:3: error: previous declaration as `int alpha'

-- 
           Summary: confusing error message on ibad redeclaration of anon
                    union
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mec dot gnu at mindspring dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13927