Thread overview
[Issue 1886] New: Inserting into an AA of structs with opAssign results in ArrayBoundsError
Mar 02, 2008
d-bugmail
Feb 14, 2009
d-bugmail
Dec 16, 2009
Michael Rynn
Dec 16, 2009
Michael Rynn
Dec 17, 2009
Michael Rynn
May 25, 2010
Don
Oct 19, 2010
Don
March 02, 2008
http://d.puremagic.com/issues/show_bug.cgi?id=1886

           Summary: Inserting into an AA of structs with opAssign results in
                    ArrayBoundsError
           Product: D
           Version: 2.011
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: ludwig@informatik.uni-luebeck.de


Inserting into an associative array with structs as value types results in a runtime error, as soon as the struct defines an opAssign. Structs without opAssign work fine.

The code below will abort at runtime with an ArrayBoundsError exception:

-----------------
struct S {
        void opAssign( in S s ){}
}

int main()
{
        S[string] aa;
        aa["test"] = S(); // throws ArrayBoundsError

        return 0;
}
-----------------
Error: ArrayBoundsError bug_aaassign.d(8)


-- 

February 14, 2009
http://d.puremagic.com/issues/show_bug.cgi?id=1886


burton-radons@shaw.ca changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burton-radons@shaw.ca
           Severity|normal                      |major
            Version|2.011                       |2.023




------- Comment #1 from burton-radons@shaw.ca  2009-02-14 12:35 -------
This bug still exists (2.023) and makes it impossible to use a Variant as the value in an associative array, which is one of the most important uses for it. However, the error message has changed to "core.exception.RangeError@test(16): Range violation".


-- 

December 16, 2009
http://d.puremagic.com/issues/show_bug.cgi?id=1886


Michael Rynn <y0uf00bar@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |y0uf00bar@gmail.com


--- Comment #2 from Michael Rynn <y0uf00bar@gmail.com> 2009-12-16 12:59:21 PST ---
Its not adding just opAssign. Having post-blit in a struct can do it too. Documentation on struct in Associative Arrays in D2 is out of date.  Probably because it mostly does not work. To return a pointer to the struct have to take address of this



struct pblit {
     int x;

     pblit* opAssign(ref const pblit S)
     {
         this.x = S.x;

     }

     this(this)
     {
     }
     ~this()
     {
     }
}

void main(char[][] args)
{
    pblit[string]   map;
    string[pblit]   rmap;

    pblit val;
    val.x = 12;

    rmap[val] = "test";   // this works
    map["test"] = val;    // oops! range error
}

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--- Comment #3 from Michael Rynn <y0uf00bar@gmail.com> 2009-12-16 13:09:14 PST ---
We are now 2.037 and still not fixed.

The documentation on D2.0 Associative Arrays with struct is wrong.
Adding the post-blit still allows the struct to be used as key, but not a
value. This is wierd. What is the approved opAssign example return type now?

     pblit opAssign(ref const pblit S)
     {
         this.x = S.x;
         return this; // return a value
     }

     -- OR ---
     pblit* opAssign(ref const pblit S)
     {
         this.x = S.x;
         return &this; // this is a struct!
     }

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December 17, 2009
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--- Comment #4 from Michael Rynn <y0uf00bar@gmail.com> 2009-12-16 19:10:53 PST ---
Sorry to split into 3 bits.  When I press tab the focus goes to the submit button.

I stepped thru the x86 code generated in the debugger using Visual Studio 2008 after conversion with cv2pdb -- great tool.

In the noblit case :- The code  calls __aaGet

    the arguments are the key, TypeInfo_Aa@__init, and address of the
map structure.
    An address? is returned in EAX, which is checked for null,
    The value of nval is directly blitted to the returned address.

    __aaGet does the checking if the key points to existing value,
and allocates memory for new value as required.


In the postblit case the generated code seems to miss the point entirely.

The code initially makes a temporary copy of val. and calls the postblit constructor, which calls this(this).  --> @postblit__cpctor --> postblit@__postblit.

Why is a prior temporary copy required, when one hopes that its the map that is going to provide the final destination?

From the temporary copy, it then pushes the bits value of the temporary
(not the address!),
then the key, then TypeInfo_Aa@__init, and address of map.

The code then calls __aaGetRvalue  ( not __aaGet )

__aaGetRvalue gives up very quickly, failing its first check.

     It pushes registers, and then checks the address in [esp+18h].
     This being null, it pop-exits with null as the result in eax.
     Obviously __aaGetRvalue is expecting something else to be setup.


     Presumably if __aaGetRvalue actually worked, it would just reblit
the value in the temporary to the memory it allocated or found, without
calling postblit again.

I would like to see ideally.
    No temporary copy made initially.

    The map lookup able to allocate or find memory for the key.
    The address returned.
    The copy made and then post-blit called.

Failing that , please fix up __aaGetRvalue so it does the right thing.

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May 25, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=1886


Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |clugdbug@yahoo.com.au


--- Comment #5 from Don <clugdbug@yahoo.com.au> 2010-05-25 13:27:52 PDT ---
Duplicate of bug 2451. However there is some useful information in the comments for this bug.

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October 19, 2010
http://d.puremagic.com/issues/show_bug.cgi?id=1886


Don <clugdbug@yahoo.com.au> changed:

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


--- Comment #6 from Don <clugdbug@yahoo.com.au> 2010-10-19 15:13:39 PDT ---
The patch for bug 2451 fixes this. Clearly a duplicate.

*** This issue has been marked as a duplicate of issue 2451 ***

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