http://d.puremagic.com/issues/show_bug.cgi?id=9130

           Summary: Wrong codegen for comile time constructed struct
           Product: D
           Version: D2
          Platform: x86
        OS/Version: All
            Status: NEW
          Severity: critical
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: samukha@voliacable.com


--- Comment #0 from Max Samukha <samukha@voliacable.com> 2012-12-09 16:21:05 PST ---
This is the minimal test case I have for now. Wrong value is generated for the 'name' member causing the following to segfault at runtime (1):

struct S
{
    void bar()
    {
    }
}

struct Meta
{
    string name;

    void construct(alias m)()
    {
        name = "bar";
    }
}

struct Function
{
    Meta super_;
    alias super_ this;
    bool break_;

    void construct(alias f)()
    {
        super_.construct!f();
    }

    void dynConstruct(alias f)()
    {
        if (!break_)
        {
            break_ = true;
            meta!(__traits(getOverloads, S, "bar")[0]);
        }
    }
}

@property void meta(alias m)()
{
    static Function md = function()
        {
            Function r;
            r.construct!m();
            return r;
        }();

    assert(md.name == "bar"); // (1)
    md.dynConstruct!m();
}

void main()
{
    meta!(S.bar);
}

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Maxim Fomin <maxim@maxim-fomin.ru> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |maxim@maxim-fomin.ru


--- Comment #1 from Maxim Fomin <maxim@maxim-fomin.ru> 2012-12-10 06:52:27 PST ---
It happens because of invalid usage of traits. If spec is right, getOverloads works with classes and even if it does work with structs, dmd complains "need 'this' for bar type void()"

struct S
{
    void bar() { }
}

void meta(alias m) ()
{
       // insert some usage of m here
       // to force dmd to reject code
}

void main()
{
    //Error: need 'this' for bar type void()
    //auto x = __traits(getOverloads, S, "bar")[0];
        //But template silently 'eats' erroneous construct
    meta!(__traits(getOverloads, S, "bar")[0]);
}

In your code if you comment out "meta!(__traits(getOverloads, S, "bar")[0]);"
everything would work fine.

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--- Comment #2 from Max Samukha <samukha@voliacable.com> 2012-12-10 08:30:45 PST ---
(In reply to comment #1)
> It happens because of invalid usage of traits. If spec is right, getOverloads works with classes and even if it does work with structs, dmd complains "need 'this' for bar type void()"

Sorry, it is a valid usage. There should be no restrictions on the kind of overloaded functions passed to getOverloads.

> 
> struct S
> {
>     void bar() { }
> }
> 
> void meta(alias m) ()
> {
>        // insert some usage of m here
>        // to force dmd to reject code
> }
> 
> void main()
> {
>     //Error: need 'this' for bar type void()
>     //auto x = __traits(getOverloads, S, "bar")[0];

Sure, calling a member function without a context pointer will and should produce an error. Passing it to a template, storing in a tuple, getting its type, static address and other meta-data are valid operations and should be allowed.

>         //But template silently 'eats' erroneous construct
>     meta!(__traits(getOverloads, S, "bar")[0]);
> }
> 
> In your code if you comment out "meta!(__traits(getOverloads, S, "bar")[0]);"
> everything would work fine.

I need to use getOverloads. BTW, if you change S to a class and mark bar() static you will get the same segfault.

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--- Comment #3 from Maxim Fomin <maxim@maxim-fomin.ru> 2013-02-04 00:55:34 PST ---
Reduced:

class S { void bar() { } }

import core.stdc.stdio : printf;

struct Function
{
    int[] ai = [1,2,3];
}

@property void meta(alias m)()
{
    static Function md;
    printf("length = %d\n", md.ai.length);
    printf("ptr = %p\n", md.ai.ptr);
    md.ai[0] = 0;
}

void main()
{
    meta!(__traits(getOverloads, S, "bar")[0]);
    meta!(S.bar);
}

Strangely dmd generates two functions and places two md objects in thread local storage (at least it reports do so). It seems that whatever __traits returns, is treated differently from S.bar.

This leads to following problem. When above code is run, it outputs:

length = 3
ptr = 0xc6c540
Segmentation fault

So, thread local md object seems to be allocated, but array pointer is corrupted. If either of meta invocations is commented out, the code prints

length = 3
ptr = 0x636298

So, pointer is valid. Ironically 0x636298 * 2 meta functions = 0xC6C530

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--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2013-02-04 01:16:56 PST ---
With git head and Windows 7 32bit PC, no segmentation fault occurs. I think you need to report actual environment and compiler version.

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--- Comment #5 from Maxim Fomin <maxim@maxim-fomin.ru> 2013-02-04 01:20:55 PST ---
(In reply to comment #4)
> With git head and Windows 7 32bit PC, no segmentation fault occurs. I think you need to report actual environment and compiler version.

I used linux64 and git head (actually it was 2-3 days old).

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--- Comment #6 from Maxim Fomin <maxim@maxim-fomin.ru> 2013-02-04 01:41:01 PST ---
(In reply to comment #4)
> With git head and Windows 7 32bit PC, no segmentation fault occurs. I think you need to report actual environment and compiler version.

Still happens with git head. Neither original, nor reduced example segfaults at runtime on windows on 2.061, so the issue seems to be either linux bug or common one but fixed in 2.061 windows release.

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
           Severity|critical                    |regression


--- Comment #7 from Don <clugdbug@yahoo.com.au> 2013-05-07 23:43:50 PDT ---
Confirmed on Linux, it's actually a regression.
This worked in 2.057, failed in 2.059.

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugzilla@digitalmars.com


--- Comment #8 from Walter Bright <bugzilla@digitalmars.com> 2013-05-23 02:12:59 PDT ---
https://github.com/D-Programming-Language/dmd/pull/2068

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--- Comment #9 from github-bugzilla@puremagic.com 2013-05-23 18:07:37 PDT ---
Commits pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/8265f070e11cb59c7390957abd2f1257290bfd61 fix Issue 9130 - Wrong codegen for compile time constructed struct

https://github.com/D-Programming-Language/dmd/commit/bb9a2a95d6f204cbb88a54a239069d4ddf0f23b5 Merge pull request #2068 from WalterBright/fix9130

fix Issue 9130 - Wrong codegen for compile time constructed struct

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