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June 20, 2011
[Issue 6180] New: Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180

          Summary: Private has no effect on types in modules
          Product: D
          Version: D2
         Platform: Other
       OS/Version: Windows
           Status: NEW
         Keywords: accepts-invalid
         Severity: major
         Priority: P2
        Component: DMD
       AssignedTo: nobody@puremagic.com
       ReportedBy: andrej.mitrovich@gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2011-06-19 17:36:05 PDT ---
Example:

foo.d:
module foo;

private
{
   int x;
   class Foo {}
}

main.d:
module main;

import foo;

void main() 
{
   // x = 5; // Error: module main foo.x is private
   auto foo = new Foo();  // accepted!!
}

Currently I have a problem with clashing symbols between
std.concurrency.MessageBox which is a private class and the Windows bindings
win32.winuser.MessageBox, which is a public function. It's a very commonly used
function btw. My workaround is this after the last import:

alias win32.winuser.MessageBox MessageBox;

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June 21, 2011
[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


Peter Alexander <peter.alexander.au@gmail.com> changed:

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--- Comment #1 from Peter Alexander <peter.alexander.au@gmail.com> 2011-06-21 08:05:56 PDT ---
I'm working on fixing the fact that protection is ignored on user-defined
types, but until someone says otherwise, I won't be changing the overload
resolution rules to account for protection. Unless I've missed it, no where in
TDPL or on the website does it say that private symbols are invisible from
other modules, it only says that they cannot be accessed.

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June 25, 2011
[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180



--- Comment #2 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2011-06-25 09:46:08 PDT ---
I don't really understand this notion of "visibility" vs "accessibility".

Can someone show me some code that shows the difference between the two?

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June 25, 2011
[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


Jonathan M Davis <jmdavisProg@gmx.com> changed:

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--- Comment #3 from Jonathan M Davis <jmdavisProg@gmx.com> 2011-06-25 10:06:39 PDT ---
In general, if a function is visible, then the compiler knows about it. If it
weren't visible, then the compiler wouldn't really see it when a module
imported the module that it's in. If it's visible but inaccessible, then the
compiler can see it, but it won't allow you to use it. So, for instance, if you
tried to use a private function, then it could complain about the function
being private, so you can't use it. But if it were not visible, then the
compiler would have to complain that you were trying to use a symbol that it
didn't know about.

Private symbols are perfectly visibile. They're just not accessible. All that
public, package, protected, and private affect is accessibility, not
visibility. They're _access_ modifiers. And overload resolution occurs _before_
accessibility is checked, which is part of the reason that you've been running
into issues with private stuff conflicting with public stuff.

You can check out this explanation with regards to C++ (which is essentially
the same):
http://meditation-art.blogspot.com/2007/11/c-function-visibility-and-accessibility.html

Also, look into NVI (Non-Virtual Inheritance). Herb Sutter discusses it in C++
here: http://www.gotw.ca/publications/mill18.htm

Assuming that private functions are overridable (which according to TDPL, they
should be, but they aren't currently in D), then derived classes can override
private functions without being able to call them. Andrei discusses it starting
at page 213 of TDPL. That wouldn't be possible if private functions weren't
visible.

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[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180



--- Comment #4 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2011-06-25 10:13:15 PDT ---
Thanks Jon, that sheds the light on the issue. I guess this will be difficult
to solve then.

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August 21, 2011
[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


Christian Kamm <kamm-removethis@incasoftware.de> changed:

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        Resolution|                            |DUPLICATE


--- Comment #5 from Christian Kamm <kamm-removethis@incasoftware.de> 2011-08-20 23:22:20 PDT ---
*** This issue has been marked as a duplicate of issue 1441 ***

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September 05, 2012
[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


Walter Bright <bugzilla@digitalmars.com> changed:

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--- Comment #6 from Walter Bright <bugzilla@digitalmars.com> 2012-09-04 19:54:26 PDT ---
Jonathan's summary is correct.

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[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180



--- Comment #7 from Jonathan M Davis <jmdavisProg@gmx.com> 2012-09-04 20:00:57 PDT ---
However, it _would_ be really nice if we could at least make it so that private
functions weren't considered in overload resolution. As it stands, things like
private aliases are completely useless because they essentially pollute the
global namespace (in the sense that they can cause overload conflicts, forcing
you to use the full path for the function, even though the private one is
inaccessible).

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[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


dawg@dawgfoto.de changed:

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--- Comment #8 from dawg@dawgfoto.de 2012-09-05 06:03:29 PDT ---
>And overload resolution occurs _before_ accessibility is checked

Not until we fix Bug 3254. The same bug thing now applies to the template
access checks.

>Private symbols are perfectly visibile. They're just not accessible.
>...
>You can check out this explanation with regards to C++ (which is essentially
the same)

>However, it _would_ be really nice if we could at least make it so that private
functions weren't considered in overload resolution.

In C++ headers are common and allow to hide implementation symbols. D's current
workaround are handwritten di files (object, core.thread) but we need a better
solution that is scalable and doesn't add redundancy. So far I only came up
with
HideModuleMembers which hides protected module level symbols but keeps access
checks and overloading for nested scopes.
https://github.com/D-Programming-Language/dmd/pull/739

Probably it's time to rediscuss this on the mailing list.
http://www.digitalmars.com/d/archives/digitalmars/D/visibility_vs._accessibility_of_protected_symbols_157598.html

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[Issue 6180] Private has no effect on types in modules
http://d.puremagic.com/issues/show_bug.cgi?id=6180


timon.gehr@gmx.ch changed:

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--- Comment #9 from timon.gehr@gmx.ch 2012-09-05 17:59:31 PDT ---
(In reply to comment #6)
> Jonathan's summary is correct.

It shouldn't be. The summary obviously describes horribly broken behaviour.

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