Unable to prevent inheritance in CC compiler

Question

On Solaris Studio 12.2's C++ compiler (CC), this runs without errors:
class Base;
class Baselock {
   friend class Base;
   Baselock() {cout<<"Constructor to Baselock"<<endl; }
class Base : virtual Baselock {
public:
   Base() {cout<<"Constructor to Base"<<endl; }
class Derived : public Base {
public:
   Derived() {cout<<"Constructor to Derived"<<endl; }
int main() {
   Derived D;
   return 0;
}By ISO C++ standards, an object of class "Derived" cannot be created, as it does not have access to "Baselock"'s constructor. This is an indirect procedure to prevent inheritance of a base class. In g++ as well as VC++, as expected, we get the error "Baselock::Baselock() is not accessible in this (Derived's object's) context". But we don't get error on CC compiler.
What can be the intended purpose of such a behavior?
Edited by: user9546596 on Jan 3, 2011 1:34 AM
Edited by: user9546596 on Jan 3, 2011 4:46 AM

Answer 1

The compiler warns about access under the +w (additional warnings) option.
Originally, the compiler made this access an error. We found that some popular compilers accepted similar code, and that some Open Source code failed to compile. We reduced the error to an optional warning.
With popular compilers now making this access an error, we can revisit our earlier decision only to warn about the code. Please file a bug report on the C++ compiler at http://bugs.sun.com so we have a record of the request.
In the mean time you can convert this warning to an error, but unfortunately not very conveniently.
Add the +w option so the compiler generates this warning, along with possibly other warnings, depending on  your code, and add the -errtags option. Each warning will display a tag. Example:
% CC +w -errtags z.cc
"z.cc", line 16: Warning, vbcinaccess: The constructor/destructor Baselock::Baselock()
of indirect virtual base class is not accessible from Derived::Derived().
1 Warning(s) detected. Now you can use -errwarn=<tag> to convert a warning into an error, and -erroff=<tag> to turn off a warning.
% CC +w -errwarn=vbcinaccess z.cc
"z.cc", line 16: Error: The constructor/destructor Baselock::Baselock()
of indirect virtual base class is not accessible from Derived::Derived().
1 Error(s) detected. Related bug reports:
6566513 compiler fails to generate the expected failure from the negative test case
6841693 Need liberalization of too strong accessibility control after fix for 6566513