[Bug c++/39905] New: static downcast through protectedly inherited base class rejected

[Bug c++/39905] New: static downcast through protectedly inherited base class rejected

[fang at csl dot cornell dot edu]

The following test case was accepted in g++-4.3.x and earlier, but rejected by
4.4.0.  
Code is possibly invalid, can any standard-fluent experts comment?  

// prNEW.cc -- test case
class base {
protected:
void
foo(void) const;
};

class derived : protected base {
public:
void
bar(void) const {
        base::foo();
}
};

void
base::foo(void) const {
        static_cast<const derived&>(*this);
}

% g++-4 -ansi -pedantic-errors -Wold-style-cast -Woverloaded-virtual -W -Wextra
-Wall -Wundef -Wshadow -Wno-unused-parameter -Wpointer-arith -Wcast-qual
-Wcast-align -Wconversion -Werror -std=c++0x -Wno-error=conversion -g -O3
-Wno-long-long -c prNEW.cc -o prNEW.o

prNEW.cc: In member function 'void base::foo() const':
prNEW.cc:17: error: 'base' is an inaccessible base of 'derived'

VERY closely related to pr12265, the only real change is from private to
protected inherited base.


-- 
           Summary: static downcast through protectedly inherited base class
                    rejected
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fang at csl dot cornell dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39905

[Bug c++/39905] static downcast through protectedly inherited base class rejected

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2009-04-26 00:42 -------
Comment #1 in Bug 12265, explains exactly why this code is invalid.  Protected
base classes are non accessible in other clases besides in  derived and derived
classes of derived.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39905

[Bug c++/39905] static downcast through protectedly inherited base class rejected

[fang at csl dot cornell dot edu]

------- Comment #2 from fang at csl dot cornell dot edu  2009-04-26 00:52 -------
Subject: Re:  static downcast through protectedly inherited
 base class rejected

> ------- Comment #1 from pinskia at gcc dot gnu dot org  2009-04-26 00:42 -------
> Comment #1 in Bug 12265, explains exactly why this code is invalid. 
> Protected base classes are non accessible in other clases besides in 
> derived and derived classes of derived.

Ok, I get it.  "not accessible to classes besides ..." excludes the 
base class itself.

I see your reflex time has not slowed, pinski.  :)

Fang


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39905