From cfe-dev  Thu Feb 14 15:11:45 2013
From: Olivier Goffart <ogoffart () kde ! org>
Date: Thu, 14 Feb 2013 15:11:45 +0000
To: cfe-dev
Subject: [cfe-dev] Access to static protected member from friends of derived classes.
Message-Id: <1406271.8h7aOWuEp7 () gargamel>
X-MARC-Message: https://marc.info/?l=cfe-dev&m=136085503503259

Hi,

A few years ago, I was trying to fix the bug 6840 [1] that relates to acces=
s to =

static protected member from friends of derived classes.

I made a patch that fixes it at the time, but it was rejected because this =
was =

considered as a drafting error in the standard [2]. =


Recently, I attended a talk by a Debian dev who tried to compile all debian =

packages with clang. And that bug was one frequent cause of compilation err=
or. =

[3]

I was wondering if it was not time to revisit the decision, and consider th=
at =

this issue should be fixed after all.

The problem is the following:

class N { protected: static int m; };
class P : public N { friend class R; };
class R { =

  int foo() { =

     return N::m; // should work because the access is given via P.
    // but clang gives an error:
    // error: 'm' is a protected member of 'N'
  }
};

C++11 =A711.4  explicitly states this is permitted, with an example. And gc=
c =

supports that fine.

Opinions?
-- =

Olivier

[1] http://llvm.org/bugs/show_bug.cgi?id=3D6840
[2] http://lists.cs.uiuc.edu/pipermail/cfe-dev/2010-June/009310.html
[3] http://sylvestre.ledru.info/blog/media/5/rebuild-debian-presentation-cl=
ang-July-10.pdf  (slide 35)

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