Weird array setting behaviour on Windows(-m64)

[rikki cattermole via Digitalmars-d-learn]

On 14/04/2016 2:49 AM, ref2401 wrote:
> Hello,
>
> I got stuck with a weird array setting behaviour and I need help. Just
> have a look at the example.
>
> OS: Win 8.1 Pro
> DMD: v2.071.0
> Build-cmd: dmd main.d -ofconsole-app.exe -debug -unittest -g -wi -m64
>
> module dmain;
> import std.stdio;
>
> struct Vec {
>      float a;
> }
>
> void main(string[] args) {
>      Vec[] array = new Vec[4];
>
>      writeln("before: ", array); //  prints [Vec(nan), Vec(nan),
> Vec(nan), Vec(nan)]
>
>      array[] = Vec(24);
>
>      writeln("after: ", array); // prints [Vec(0), Vec(0), Vec(0), Vec(0)]
> }
>
> Seems like slicing is broken in general. All the following variations
> produce different results but they are all wrong.
> array[] = Vec(24);
> array[0 .. 1] = Vec(24);
> array[0 .. $] = Vec(24);
>
> It works as expected if I do one of the following things:
> 1. Get rid of -m64. If I compile with -m32 flag then I cannot replicate
> the issue.
>
> 2. Changing the type of the Vec.a field from float to real, int, uint,
> long, ulong fixes the issue. Double still causes the issues.
>
> 3. Adding new fields to the Vec struct.
>
> 3.1. Vec {float a, b; } still does not work but the result is slightly
> different.
> array[] = Vec(24, 5);
> writeln("after: ", array); // [Vec(5, 0), Vec(5, 0), Vec(5, 0), Vec(5, 0)]
>
> 3.2. Vec { float a, b, c; } works fine.
>
> 4. Using index operator: array[0] = Vec(24) works fine

Verified that it is a codegen problem for Win64 and not *nix.
Please file a bug report.