Merge pull request github#4654 from tamasvajk/feature/csharp9-parens-pattern

C#: Handle parenthesized pattern extraction

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CSharp/Entities/Expressions/Patterns/Pattern.cs

@@ -11,6 +11,9 @@ internal static Expression Create(Context cx, PatternSyntax syntax, IExpressionP
         {
             switch (syntax)
             {
+                case ParenthesizedPatternSyntax parenthesizedPattern:
+                    return Pattern.Create(cx, parenthesizedPattern.Pattern, parent, child);
+
                 case ConstantPatternSyntax constantPattern:
                     return Expression.Create(cx, constantPattern.Expression, parent, child);
 

csharp/ql/test/library-tests/csharp9/ParenthesizedPattern.cs

@@ -0,0 +1,30 @@
+using System;
+
+class T { }
+
+class ParenthesizedPattern
+{
+    void M1(object o)
+    {
+        if (o is {} p1)
+        {
+        }
+
+        if (o is ({} p2))
+        {
+        }
+    }
+
+
+    void M2(object o)
+    {
+        var r = o switch
+        {
+            1 => 1,
+            (2) => 2,
+            T t when t is {} => 3,
+            (object o1) when o1 is ({}) => 4,
+            (string _) => 5
+        };
+    }
+}

csharp/ql/test/library-tests/csharp9/PrintAst.expected

@@ -184,6 +184,67 @@ NativeInt.cs:
 #   25|               0: [CastExpr] (...) ...
 #   25|                 1: [LocalVariableAccess] access to local variable x
 #   25|               1: [LocalVariableAccess] access to local variable v
+ParenthesizedPattern.cs:
+#    3| [Class] T
+#    5| [Class] ParenthesizedPattern
+#    7|   5: [Method] M1
+#    7|     -1: [TypeMention] Void
+#-----|     2: (Parameters)
+#    7|       0: [Parameter] o
+#    7|         -1: [TypeMention] object
+#    8|     4: [BlockStmt] {...}
+#    9|       0: [IfStmt] if (...) ...
+#    9|         0: [IsExpr] ... is ...
+#    9|           0: [ParameterAccess] access to parameter o
+#    9|           1: [RecursivePatternExpr] { ... }
+#    9|             0: [LocalVariableDeclExpr] Object p1
+#    9|             3: [PropertyPatternExpr] { ... }
+#   10|         1: [BlockStmt] {...}
+#   13|       1: [IfStmt] if (...) ...
+#   13|         0: [IsExpr] ... is ...
+#   13|           0: [ParameterAccess] access to parameter o
+#   13|           1: [RecursivePatternExpr] { ... }
+#   13|             0: [LocalVariableDeclExpr] Object p2
+#   13|             3: [PropertyPatternExpr] { ... }
+#   14|         1: [BlockStmt] {...}
+#   19|   6: [Method] M2
+#   19|     -1: [TypeMention] Void
+#-----|     2: (Parameters)
+#   19|       0: [Parameter] o
+#   19|         -1: [TypeMention] object
+#   20|     4: [BlockStmt] {...}
+#   21|       0: [LocalVariableDeclStmt] ... ...;
+#   21|         0: [LocalVariableDeclAndInitExpr] Int32 r = ...
+#   21|           -1: [TypeMention] int
+#   21|           0: [LocalVariableAccess] access to local variable r
+#   21|           1: [SwitchExpr] ... switch { ... }
+#   21|             -1: [ParameterAccess] access to parameter o
+#   23|             0: [SwitchCaseExpr] ... => ...
+#   23|               0: [ConstantPatternExpr,IntLiteral] 1
+#   23|               2: [IntLiteral] 1
+#   24|             1: [SwitchCaseExpr] ... => ...
+#   24|               0: [ConstantPatternExpr,IntLiteral] 2
+#   24|               2: [IntLiteral] 2
+#   25|             2: [SwitchCaseExpr] ... => ...
+#   25|               0: [VariablePatternExpr] T t
+#   25|                 0: [TypeMention] T
+#   25|               1: [IsExpr] ... is ...
+#   25|                 0: [LocalVariableAccess] access to local variable t
+#   25|                 1: [RecursivePatternExpr] { ... }
+#   25|                   3: [PropertyPatternExpr] { ... }
+#   25|               2: [IntLiteral] 3
+#   26|             3: [SwitchCaseExpr] ... => ...
+#   26|               0: [VariablePatternExpr] Object o1
+#   26|                 0: [TypeMention] object
+#   26|               1: [IsExpr] ... is ...
+#   26|                 0: [LocalVariableAccess] access to local variable o1
+#   26|                 1: [RecursivePatternExpr] { ... }
+#   26|                   3: [PropertyPatternExpr] { ... }
+#   26|               2: [IntLiteral] 4
+#   27|             4: [SwitchCaseExpr] ... => ...
+#   27|               0: [TypeAccessPatternExpr] access to type String
+#   27|                 0: [TypeMention] string
+#   27|               2: [IntLiteral] 5
 TypeParameterNullability.cs:
 #    1| [Interface] I1
 #    3| [Class] A2