[cfe-dev] ParseClassSpecifier: can "unions" inherit?

[Ted Kremenek]

I just noticed the following code fragment in ParseClassSpecifier:

   // Parse the tag portion of this.
   DeclTy *TagDecl = Actions.ActOnTag(CurScope, TagType, TK, StartLoc,  
Name,
                                      NameLoc, Attr);

   // Parse the optional base clause (C++ only).
   if (getLang().CPlusPlus && Tok.is(tok::colon)) {
     ParseBaseClause(TagDecl);
   }

It appears from the code that the 'if' branch can be taken even if the  
tag decl is a union.  Is this valid in the C++ grammar?  That is, can  
there be a "base clause" for unions in C++, and if so, what does that  
mean?