Bug 15921 – Win64: wrong codegen with array of structs slicing

Array setting behaviour produces wrong results. 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

It works for me with the latest dmd.