Why is 32 bit executable not running under WoW64?

Question

On my 32 bit system (Windows 10), I created a very simple Windows Forms (.NET FW 3.5) application:

        bool x86 = IntPtr.Size == 4;

        if (x86)
        {
            label1.Text = "OS: 32 bit";
        }
        else // IntPtr.Size == 8
        {
            label1.Text = "OS: 64 bit";

            // For following method, see:
            // http://stackoverflow.com/a/336729/360840
            if (InternalCheckIsWow64())
            {
                label1.Text += "; 32 bit program running under WoW64";
            }
        }

In Visual Studio 2015, under Properties -> Build, I set Platform Target as x86.

I took this executable to a 64 bit Windows Server 2012 Datacenter edition, and ran it. I fully expected to see it report itself as running under WoW64, but was surprised to find out that wasn't the case; it only reports that the architecture is 64 bit, but does not display the "; 32 bit program running under WoW64" part.

Why is this, and what is going on?

Answer 1

IntPtr.Size is set by the process itself (or better said, the build target), not by the OS.

A program build with an x86 target in c# will always have IntPtr.Size = 4, while x64 will always have IntPtr.Size = 8. This is in fact a check for the process, not the OS.

Edit: The answer in the linked topic states exactly the same.