http://d.puremagic.com/issues/show_bug.cgi?id=6052

           Summary: [CTFE] Structs elements in an array are treated like
                    reference type
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Mac OS X
            Status: NEW
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: kennytm@gmail.com


--- Comment #0 from kennytm@gmail.com 2011-05-24 09:06:57 PDT ---
Test case:

--------------------------------------------------
struct Bug6052 {
    int a;
}

bool bug6052() {
    Bug6052[2] arr;
    for (int i = 0; i < 2; ++ i) {
        Bug6052 el = {i};
        Bug6052 ek = el;
        arr[i] = el;
        el.a = i + 2;
        assert(ek.a == i);      // ok
        assert(arr[i].a == i);  // fail
    }
    assert(arr[1].a == 1);  // ok
    assert(arr[0].a == 0);  // fail
    return true;
}

static assert(bug6052());
--------------------------------------------------
x.d(16): Error: assert(arr[cast(uint)i].a == i) failed
x.d(23): Error: cannot evaluate bug6052() at compile time
x.d(23): Error: static assert  (bug6052()) is not evaluatable at compile time
--------------------------------------------------

Setting a struct value on a array should perform a bit-copy, so modifying 'el' should not affect 'arr[i]', but currently CTFE does it wrongly.

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--- Comment #1 from kennytm@gmail.com 2011-05-24 09:10:47 PDT ---
Note: the last 2 asserts refer to the case when the line 'el.a = i + 2;'  is commented out.

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kennytm@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |regression


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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |clugdbug@yahoo.com.au
         Resolution|                            |FIXED


--- Comment #2 from Don <clugdbug@yahoo.com.au> 2011-05-30 17:02:43 PDT ---
A related test case which also fails, but involves static arrays rather than structs:

bool bug6052b() {
    int[][1] arr;
    int[1] z = [7];
    arr[0] = z;
    assert(arr[0][0] == 7);
    arr[0] = z;
    z[0] = 3;
    assert(arr[0][0] == 3);
    return true;
}

static assert(bug6052b());


https://github.com/D-Programming-Language/dmd/commit/bccb02ad1d8578767f99efeab4a230a229e24392

Case b: https://github.com/D-Programming-Language/dmd/commit/2ee56a0038ccac3b2225b7feda9d69798cc203e3

D1: https://github.com/D-Programming-Language/dmd/commit/bccb02ad1d8578767f99efeab4a230a229e24392

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kennytm@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |


--- Comment #3 from kennytm@gmail.com 2011-05-31 01:34:45 PDT ---
The bug still exists if the the struct has a constructor and we're appending to a dynamic array....

---------------------------------------------
struct Bug6052c {
    int x;
    this(int a) { x = a; }
}
static assert({
    Bug6052c[] pieces = [];
    for (int c = 0; c < 2; ++ c)
        pieces ~= Bug6052c(c);
    assert(pieces[1].x == 1);   // ok
    assert(pieces[0].x == 0);   // asserts
    return true;
}());
---------------------------------------------
x.d(10): Error: assert(pieces[0u].x == 0) failed
<snipped>
---------------------------------------------

or filling the uninitialized portion of a dynamic array....

---------------------------------------------
static assert({
    int[1][] pieces = [];
    pieces.length = 2;
    for (int c = 0; c < 2; ++ c)
        pieces[c][0] = c;
    assert(pieces[1][0] == 1);   // ok
    assert(pieces[0][0] == 0);   // asserts
    return true;
}());
---------------------------------------------
x.d(7): Error: assert(pieces[0u][0u] == 0) failed
<snipped>
---------------------------------------------

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED


--- Comment #4 from Don <clugdbug@yahoo.com.au> 2011-06-01 22:49:08 PDT ---
case c: https://github.com/D-Programming-Language/dmd/commit/0ae51ead31246c7db23438d1d13bbfd8a2145f2f

case d: https://github.com/D-Programming-Language/dmd/commit/084258c32964dc61333e057065339895d9aca6f0

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