Possible bug in associative array implementation (and/or @safe checking)

[Aaron D. Trout]

Hello all! I'm a mathematician at Chatham University in 
Pittsburgh, PA (USA). I use D for research, and I'm a frequent 
lurker on the forums. I think I found a bug, but I want to make 
sure I'm not just doing something silly. (I'm happy to file a 
bugzilla issue if it turns out to be a legitimate and previously 
unknown bug.) Thanks in advance for the feedback.

Tested on 64-bit linux, DMD 2.080.0 and LDC 1.9.0.

code:
---------------------------------------------------
import std.range, std.algorithm, std.conv, std.stdio;

// return a newly constructed immutable static array
immutable(int)[len] toImmutStaticArray(size_t len, R)(R range)
{
     int[len] r;
     copy(range, r[]);
     return r;
}

void main() @safe
{
     int[int[]] aaHeapKeys;
     int[int[]] aaStackKeys;
     int[int[2]] aaStaticKeys;

     int[] setA = [2,3,5];
     int[] setB = [2,4,3,9,5,25];

     // range of ranges: [[5, 25], [2, 4], [3, 9]]
     auto sets = setA.map!(j => setB.filter!(i => i % j == 0));

     foreach(s; sets)
     {
         // insert using a slice of imuutable(int) on the heap as 
the key
         auto heapSlice = s.array.idup;
         aaHeapKeys[heapSlice] = 0;

         // insert using an identical slice of immutable(int) on 
the stack
         // as the key
         auto buffer = s.toImmutStaticArray!2;
         auto stackSlice = buffer[0 .. s.walkLength];
         assert(stackSlice == heapSlice);
         aaStackKeys[stackSlice] = 0;

         // insert using the static array buffer as key
         aaStaticKeys[buffer] = 0;
     }

     assert(aaHeapKeys   == [[5, 25]:0, [2, 4]:0, [3, 9]:0]); // OK
     // assert(aaStackKeys  == [[5, 25]:0, [2, 4]:0, [3, 9]:0]); 
// FAILS!
     assert(aaStaticKeys == [[5, 25]:0, [2, 4]:0, [3, 
9]:0].to!(int[int[2]])); // OK

     // Note that aaStackKeys seems corrupted. Printing out 
aaStackKeys
     // gives: [[5, 25]:0, [5, 25]:0, [5, 25]:0]
     // aaStackKeys.writeln;
}