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digitalmars.D.bugs - [Issue 9021] New: Casting a class pointer to size_t and back does not return the same value

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9021

           Summary: Casting a class pointer to size_t and back does not
                    return the same value
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: malteskarupke web.de



PST ---
int main()
{
    class C { }
    C c = new C;
    C other = *cast(C *)cast(size_t) &c;
    assert(&other == &c);
    return 0;
}

That assert fires on DMD 2.060

I need this to interface with a C library where I have to pass a pointer as two
ints and then cast them back in a callback.

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Nov 13 2012
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9021


Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich gmail.com



17:47:13 PST ---

 int main()
 {
     class C { }
     C c = new C;
     C other = *cast(C *)cast(size_t) &c;
     assert(&other == &c);
     return 0;
 }
 
 That assert fires on DMD 2.060
 
 I need this to interface with a C library where I have to pass a pointer as two
 ints and then cast them back in a callback.
You are comparing references. Those are two unique references to the same object. If you want to compare the actual object address they point to use: cast(void*)other == cast(void*)c; -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 13 2012
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=9021


Malte Skarupke <malteskarupke web.de> changed:

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



PST ---


 int main()
 {
     class C { }
     C c = new C;
     C other = *cast(C *)cast(size_t) &c;
     assert(&other == &c);
     return 0;
 }
 
 That assert fires on DMD 2.060
 
 I need this to interface with a C library where I have to pass a pointer as two
 ints and then cast them back in a callback.
You are comparing references. Those are two unique references to the same object. If you want to compare the actual object address they point to use: cast(void*)other == cast(void*)c;
Ah that explains it. Thanks! -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 13 2012