Is this a possible bug in .Net Native compilation and optimization? : <p>I discovered an issue with (what might be) over-optimization in <code>.Net Native</code> and <code>structs</code>. I'm not sure if the compiler is too aggressive, or I'm too blind to see what I've done wrong. </p>

<p>To reproduce this, follow these steps:</p>

<p><strong>Step 1</strong>: Create a new Blank Universal (win10) app in <em>Visual Studio 2015 Update 2</em> targeting build 10586 with a min build of 10240. Call the project <em>NativeBug</em> so we have the same namespace.</p>

<p><strong>Step 2</strong>: Open <code>MainPage.xaml</code> and insert this label</p>

<pre><code>&lt;Page x:Class="NativeBug.MainPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      mc:Ignorable="d"&gt;

    &lt;Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"&gt;
        &lt;!-- INSERT THIS LABEL --&gt;
        &lt;TextBlock x:Name="_Label" HorizontalAlignment="Center" VerticalAlignment="Center" /&gt;
    &lt;/Grid&gt;
&lt;/Page&gt;
</code></pre>

<p><strong>Step 3</strong>: Copy/paste the following into <code>MainPage.xaml.cs</code></p>

<pre><code>using System;
using System.Collections.Generic;

namespace NativeBug
{
    public sealed partial class MainPage
    {
        public MainPage()
        {
            InitializeComponent();

            var startPoint = new Point2D(50, 50);
            var points = new[]
            {
                new Point2D(100, 100), 
                new Point2D(100, 50), 
                new Point2D(50, 100), 
            };

            var bounds = ComputeBounds(startPoint, points, 15);

            _Label.Text = $"{bounds.MinX} , {bounds.MinY}   =&gt;   {bounds.MaxX} , {bounds.MaxY}";
        }

        private static Rectangle2D ComputeBounds(Point2D startPoint, IEnumerable&lt;Point2D&gt; points, double strokeThickness = 0)
        {
            var lastPoint = startPoint;
            var cumulativeBounds = new Rectangle2D();

            foreach (var point in points)
            {
                var bounds = ComputeBounds(lastPoint, point, strokeThickness);
                cumulativeBounds = cumulativeBounds.Union(bounds);
                lastPoint = point;
            }

            return cumulativeBounds;
        }

        private static Rectangle2D ComputeBounds(Point2D fromPoint, Point2D toPoint, double strokeThickness)
        {
            var bounds = new Rectangle2D(fromPoint.X, fromPoint.Y, toPoint.X, toPoint.Y);

            // ** Uncomment the line below to see the difference **
            //return strokeThickness &lt;= 0 ? bounds : bounds.Inflate2(strokeThickness);

            return strokeThickness &lt;= 0 ? bounds : bounds.Inflate1(strokeThickness);
        }
    }

    public struct Point2D
    {
        public readonly double X;
        public readonly double Y;

        public Point2D(double x, double y)
        {
            X = x;
            Y = y;
        }
    }

    public struct Rectangle2D
    {
        public readonly double MinX;
        public readonly double MinY;
        public readonly double MaxX;
        public readonly double MaxY;

        private bool IsEmpty =&gt; MinX == 0 &amp;&amp; MinY == 0 &amp;&amp; MaxX == 0 &amp;&amp; MaxY == 0;

        public Rectangle2D(double x1, double y1, double x2, double y2)
        {
            MinX = Math.Min(x1, x2);
            MinY = Math.Min(y1, y2);
            MaxX = Math.Max(x1, x2);
            MaxY = Math.Max(y1, y2);
        }

        public Rectangle2D Union(Rectangle2D rectangle)
        {
            if (IsEmpty)
            {
                return rectangle;
            }

            var newMinX = Math.Min(MinX, rectangle.MinX);
            var newMinY = Math.Min(MinY, rectangle.MinY);
            var newMaxX = Math.Max(MaxX, rectangle.MaxX);
            var newMaxY = Math.Max(MaxY, rectangle.MaxY);

            return new Rectangle2D(newMinX, newMinY, newMaxX, newMaxY);
        }

        public Rectangle2D Inflate1(double value)
        {
            var halfValue = value * .5;

            return new Rectangle2D(MinX - halfValue, MinY - halfValue, MaxX + halfValue, MaxY + halfValue);
        }

        public Rectangle2D Inflate2(double value)
        {
            var halfValue = value * .5;
            var x1 = MinX - halfValue;
            var y1 = MinY - halfValue;
            var x2 = MaxX + halfValue;
            var y2 = MaxY + halfValue;

            return new Rectangle2D(x1, y1, x2, y2);
        }
    }
}
</code></pre>

<p><strong>Step 4</strong>: Run the application in <code>Debug</code> <code>x64</code>. You should see this label:</p>

<blockquote>
  <p>42.5 , 42.5  =>  107.5 , 107.5</p>
</blockquote>

<p><strong>Step 5</strong>: Run the application in <code>Release</code> <code>x64</code>. You should see this label:</p>

<blockquote>
  <p>-7.5 , -7.5  =>  7.5, 7.5</p>
</blockquote>

<p><strong>Step 6</strong>: Uncomment <code>line 45</code> in <code>MainPage.xaml.cs</code> and repeat step 5. Now you see the original label</p>

<blockquote>
  <p>42.5 , 42.5  =>  107.5 , 107.5</p>
</blockquote>

<hr>

<p>By commenting out <code>line 45</code>, the code will use <code>Rectangle2D.Inflate2(...)</code> which is exactly the same as <code>Rectangle2D.Inflate1(...)</code> except it creates a local copy of the computations before sending them to the constructor of <code>Rectangle2D</code>. In debug mode, these two function exactly the same. In release however, something is getting optimized out.</p>

<p>This was a nasty bug in our app. The code you see here was stripped from a much larger library and I'm afraid there might be more. Before I report this to Microsoft, I would appreciate it if you could take a look and let me know why <code>Inflate1</code> doesn't work in release mode. Why do we have to create local copies?</p>
