[Bug c++/48078] New: gcc accepts-invalid: taking address of private member function from template function

[Bug c++/48078] New: gcc accepts-invalid: taking address of private member function from template function

[cgd at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

           Summary: gcc accepts-invalid: taking address of private member
                    function from template function
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: cgd@google.com


test case (created by Bill Clarke):

class A {
 public:
 A() {}
 private:
 void APrivateMethod() { }
};

// Enable this to get a (correct) compiler error.
#if 0
void CallAPrivateMethod() {
 void (A::*fn)() = &A::APrivateMethod;
 A a;
 (a.*fn)();
}
#endif

template <typename T>
void CallAPrivateMethodTemplate() {
 void (A::*fn)() = &A::APrivateMethod;
 A a;
 (a.*fn)();
}

void CallAPrivateMethodViaTemplate() {
 CallAPrivateMethodTemplate<int>();
}


compiles successfully (incorrectly AFAIU) with pre-4.6 (4.6.0 20110311)
(I tested some versions of GCC back to 4.2.x, same problem.  They had local
mods, but none that should have caused a difference in this regard.)


FYI, clang C++ front-end flags an error as expected:

devtools/cpp_tests/x.cc:22:24: error: 'APrivateMethod' is a private member of
'A'
 void (A::*fn)() = &A::APrivateMethod;
                       ^
devtools/cpp_tests/x.cc:8:7: note: declared private here
 void APrivateMethod() { }
      ^
1 error generated.

[Bug c++/48078] gcc accepts-invalid: taking address of private member function from template function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-03-11 17:38:17 UTC ---
Access checking inside templates seems to be completely broken, see PR 47346
and the bugs I listed there, this could be a dup of one of them

[Bug c++/48078] gcc accepts-invalid: taking address of private member function from template function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.03.11 18:07:13
     Ever Confirmed|0                           |1

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-03-11 18:07:13 UTC ---
I think this is different enough from any of those others to count as a
distinct bug - confirmed

[Bug c++/48078] gcc accepts-invalid: taking address of private member function from template function

[cgd at google dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

--- Comment #3 from Chris Demetriou <cgd at google dot com> 2011-03-11 19:59:40 UTC ---
(In reply to comment #2)
> I think this is different enough from any of those others to count as a
> distinct bug - confirmed

I hadn't seen them when i filed this (didn't match the searches that I did),
but yeah, looking at them I agree.

(BTW, re: the test case: Bill Clarke works for Google so it should be
adequately assigned to the FSF already.)

Thanks!

[Bug c++/48078] gcc accepts-invalid: taking address of private member function from template function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-05-11 10:35:28 UTC ---
I've just hit another variation of this bug myself.

Reduced:

class F {
  void f();
};

template<typename>
void b() {
    (void) &F::f;
}

template void b<int>();

[Bug c++/48078] gcc accepts-invalid: taking address of private member function from template function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-05-27 15:11:29 UTC ---
This bug is probably the reason why g++ only rejects half of the testcase for
http://llvm.org/bugs/show_bug.cgi?id=8058

[Bug c++/48078] accepts-invalid: taking address of private member function from template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=41437

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This seems fixed in GCC 11+, maybe by the patch which fixed PR 41437.

[Bug c++/48078] accepts-invalid: taking address of private member function from template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |awise.gcc.bug at gmail dot com

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 70984 has been marked as a duplicate of this bug. ***

[Bug c++/48078] accepts-invalid: taking address of private member function from template function

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48078

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #7)
> This seems fixed in GCC 11+, maybe by the patch which fixed PR 41437.

Yes, GCC started to reject it with r11-1350

*** This bug has been marked as a duplicate of bug 41437 ***