http://d.puremagic.com/issues/show_bug.cgi?id=10970

           Summary: Segfault in a simple test compiled without -g.
           Product: D
           Version: D2
          Platform: x86_64
        OS/Version: Windows
            Status: NEW
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: pycerl@qq.com


--- Comment #0 from Zhouxuan <pycerl@qq.com> 2013-09-05 04:34:18 PDT ---
http://dpaste.dzfl.pl/8cc57a33

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--- Comment #1 from Zhouxuan <pycerl@qq.com> 2013-09-05 05:29:12 PDT ---
After some test, the bug is likely to be that, an Array instantiated by make!(Array!T) WITHOUT ANY ARGUMENT, cannot be used as a value of AA.

following code fail to run:

alias Array!int A;
A[int] m;
m[0] = make!A;

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--- Comment #2 from Zhouxuan <pycerl@qq.com> 2013-09-05 05:48:14 PDT ---
Further test shows that, Array just cann't be used as an value of AA in dmd2.063(on dpaste), while under git-head version of dmd, segfault only occured when an array is created by make!Array without any argument.

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

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


--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-09-05 19:34:24 PDT ---
I think this is a 64-bit only bug. Could you try compiling with -m32 to confirm?

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--- Comment #4 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-09-05 19:35:48 PDT ---
(In reply to comment #3)
> I think this is a 64-bit only bug. Could you try compiling with -m32 to confirm?

Ok nevermind, I was testing your http://d.puremagic.com/issues/show_bug.cgi?id=10970#c1 instead of the dpaste one (try not to use dpaste for short examples).

Your test-case:

-----
import std.stdio;
import std.container;
import std.process;

class A
{
    this(string name)
    {
        m[name] = make!Arr;
    }

    alias Array!A Arr;
    Arr[string] m;
}

int main()
{
    A a = new A("test");
    return 0;
}
-----

Crashes on win32 as well.

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--- Comment #5 from Zhouxuan <pycerl@qq.com> 2013-09-05 20:14:47 PDT ---
(In reply to comment #4)
> (In reply to comment #3)
> > I think this is a 64-bit only bug. Could you try compiling with -m32 to confirm?
> 
> Ok nevermind, I was testing your http://d.puremagic.com/issues/show_bug.cgi?id=10970#c1 instead of the dpaste one (try not to use dpaste for short examples).
> 
> Your test-case:
> 
> -----
> import std.stdio;
> import std.container;
> import std.process;
> 
> class A
> {
>     this(string name)
>     {
>         m[name] = make!Arr;
>     }
> 
>     alias Array!A Arr;
>     Arr[string] m;
> }
> 
> int main()
> {
>     A a = new A("test");
>     return 0;
> }
> -----
> 
> Crashes on win32 as well.

Hope it helps and the issue be fixed asap, thank you!

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monarchdodra@gmail.com changed:

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


--- Comment #6 from monarchdodra@gmail.com 2013-09-06 02:10:45 PDT ---
(In reply to comment #5)
> Crashes on win32 as well.

If I recall correctly, I think the problem is "simply" that AA has *very* bad support for types with elaborate CC, and destruction. Take this "simple" use case:

//####
import std.stdio;

int count;

struct S
{
    this(int){++count; writeln("construction");}
    this(this){assert(0);} //never called
    ~this(){--count; writeln("destruction");}
}

void main()
{
    S[int] aa;
    writeln("----");
    aa[5] = S(3);
    writeln("----");
    aa.remove(5);
    writeln("----");
    assert(aa.length == 0);
    assert(count >= 0); //Fails here
}
//####
----
construction
destruction
destruction
----
----
//####

In just this little snippet, there are *all* kinds of wrong:
1. insertion: when inserting a new item, CC ("this(this)") is never called for
some strange reason. Furthermore, destruction happens *twice* (again, for some
strange reason).
2. removal: Where's the destructor?

These use cases are probably reported already, you are experiencing the results of these defects.

Long story short, at the end of the day, your array is "over-destroyed". Given that AA is a *strongly* relies on reference counting to provide deterministic behavior, things simply don't go well.

A lot of work is being done on fixing AAs (AFAIK), but don't expect it to be
fixed any time soon.

As a workaround, you could try using slices instead of AA's?

//----
import std.stdio;

class A
{
    this(string name)
    {
        m[name] = Arr.init;
    }

    alias A[] Arr;
    Arr[string] m;
}

int main()
{
    A a = new A("test");
    return 0;
}
//----

In particular, "A" is a class, so it can't have a destructor (in the sense that a *reference* doesn't get destroyed). As such, there is minimal use to keeping an Array over a slice.

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--- Comment #7 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2013-09-06 07:18:43 PDT ---
Yeah it's very unfortunate the AA situation we have in D today, it's really giving D a bad rep.

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--- Comment #8 from Zhouxuan <pycerl@qq.com> 2013-09-06 07:22:25 PDT ---
(In reply to comment #6)
> (In reply to comment #5)
> > Crashes on win32 as well.
> 
> If I recall correctly, I think the problem is "simply" that AA has *very* bad support for types with elaborate CC, and destruction. Take this "simple" use case:
> 
> //####
> import std.stdio;
> 
> int count;
> 
> struct S
> {
>     this(int){++count; writeln("construction");}
>     this(this){assert(0);} //never called
>     ~this(){--count; writeln("destruction");}
> }
> 
> void main()
> {
>     S[int] aa;
>     writeln("----");
>     aa[5] = S(3);
>     writeln("----");
>     aa.remove(5);
>     writeln("----");
>     assert(aa.length == 0);
>     assert(count >= 0); //Fails here
> }
> //####
> ----
> construction
> destruction
> destruction
> ----
> ----
> //####
> 
> In just this little snippet, there are *all* kinds of wrong:
> 1. insertion: when inserting a new item, CC ("this(this)") is never called for
> some strange reason. Furthermore, destruction happens *twice* (again, for some
> strange reason).
> 2. removal: Where's the destructor?
> 
> These use cases are probably reported already, you are experiencing the results of these defects.
> 
> Long story short, at the end of the day, your array is "over-destroyed". Given that AA is a *strongly* relies on reference counting to provide deterministic behavior, things simply don't go well.
> 
> A lot of work is being done on fixing AAs (AFAIK), but don't expect it to be
> fixed any time soon.
> 
> As a workaround, you could try using slices instead of AA's?
> 
> //----
> import std.stdio;
> 
> class A
> {
>     this(string name)
>     {
>         m[name] = Arr.init;
>     }
> 
>     alias A[] Arr;
>     Arr[string] m;
> }
> 
> int main()
> {
>     A a = new A("test");
>     return 0;
> }
> //----
> 
> In particular, "A" is a class, so it can't have a destructor (in the sense that a *reference* doesn't get destroyed). As such, there is minimal use to keeping an Array over a slice.

Thank you, I can work around it by changing the design, however, this really need to be fixed in the near future!

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--- Comment #9 from Zhouxuan <pycerl@qq.com> 2013-09-06 07:29:53 PDT ---
(In reply to comment #7)
> Yeah it's very unfortunate the AA situation we have in D today, it's really giving D a bad rep.

Absolutely, after hanging around D community for days, I decide to start a private project in D, however, the first class I implemented broke by this issue!

FYI, I'm a game programmer and GC is an another trouble-maker for me, hope it can be improved in the near futher too.

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