C#: Add some examples with the extended property pattern syntax.

csharp/ql/test/library-tests/csharp10/PropertyPatterns.cs

@@ -0,0 +1,56 @@
+using System;
+
+public record Point(int X, int Y);
+public record Line(Point P1, Point P2);
+public record Wrap(Line L);
+
+public class PropertyPatterns
+{
+    private static Line l = new Line(new Point(1, 2), new Point(3, 6));
+    private static Wrap w = new Wrap(l);
+
+    public void M1()
+    {
+        if (l is { P1: { X: 1 } })
+        {
+        }
+
+        if (l is { P1.X: 2 })
+        {
+        }
+    }
+
+    public void M2()
+    {
+        if (w is { L: { P2: { Y: 3 } } })
+        {
+        }
+
+        if (w is { L.P2.Y: 4 })
+        {
+        }
+    }
+
+    public void M3()
+    {
+        if (w is { L: { P2.Y: 5 } })
+        {
+        }
+
+        if (w is { L.P2: { Y: 6 } })
+        {
+        }
+    }
+
+    public void M4()
+    {
+        if (l is { P1: { X: 7 }, P1: { Y: 8 } })
+        {
+        }
+
+        if (l is { P1.X: 9, P1.Y: 10 })
+        {
+        }
+    }
+}
+

csharp/ql/test/library-tests/csharp10/recordTypes.expected

@@ -1,4 +1,7 @@
 recordTypes
+| PropertyPatterns.cs:3:1:3:34 | Point |
+| PropertyPatterns.cs:4:1:4:39 | Line |
+| PropertyPatterns.cs:5:1:5:27 | Wrap |
 | RecordTypes.cs:3:1:6:2 | MyEntry |
 | RecordTypes.cs:8:1:8:53 | MyClassRecord |
 | RecordTypes.cs:10:1:10:70 | MyReadonlyRecordStruct |
@@ -9,5 +12,8 @@ recordStructs
 | RecordTypes.cs:12:1:12:51 | MyRecordStruct1 |
 | WithExpression.cs:9:1:9:47 | MyRecordStruct2 |
 recordClass
+| PropertyPatterns.cs:3:1:3:34 | Point |
+| PropertyPatterns.cs:4:1:4:39 | Line |
+| PropertyPatterns.cs:5:1:5:27 | Wrap |
 | RecordTypes.cs:3:1:6:2 | MyEntry |
 | RecordTypes.cs:8:1:8:53 | MyClassRecord |