C#: Introduce a TuplePatternExpr class.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -560,7 +560,7 @@ module LocalFlow {
     or
     exists(AssignExpr ae | ae.getLeftOperand().(TupleExpr) = e2 and ae.getRightOperand() = e1)
     or
-    exists(ControlFlowElement cfe | cfe = e2.(TupleExpr).(PatternExpr).getPatternMatch() |
+    exists(ControlFlowElement cfe | cfe = e2.(TuplePatternExpr).getPatternMatch() |
       cfe.(IsExpr).getExpr() = e1
       or
       exists(Switch sw | sw.getACase() = cfe and sw.getExpr() = e1)

csharp/ql/lib/semmle/code/csharp/exprs/Expr.qll

@@ -547,6 +547,13 @@ class PositionalPatternExpr extends PatternExpr, @positional_pattern_expr {
   override string getAPrimaryQlClass() { result = "PositionalPatternExpr" }
 }
 
+/**
+ * A tuple pattern. For example, `var (x, y)`.
+ */
+class TuplePatternExpr extends TupleExpr, PatternExpr {
+  override string getAPrimaryQlClass() { result = "TuplePatternExpr" }
+}
+
 /** A list pattern. For example `[1, 2, int y]` in `x is [1, 2, int y]`. */
 class ListPatternExpr extends PatternExpr, @list_pattern_expr {
   override string toString() { result = "[ ... ]" }

csharp/ql/test/library-tests/csharp8/PrintAst.expected

@@ -929,7 +929,7 @@ patterns.cs:
 #   57|               1: [ConstantPatternExpr,IntLiteral] 2
 #   58|         10: [BreakStmt] break;
 #   59|         11: [CaseStmt] case ...:
-#   59|           0: [TupleExpr] (..., ...)
+#   59|           0: [TuplePatternExpr] (..., ...)
 #   59|             0: [VariablePatternExpr] Int32 x
 #   59|             1: [VariablePatternExpr] Int32 y
 #   60|         12: [BreakStmt] break;
@@ -1156,7 +1156,7 @@ patterns.cs:
 #  130|                   1: [ConstantPatternExpr,IntLiteral] 2
 #  130|               2: [IntLiteral] 2
 #  131|             3: [SwitchCaseExpr] ... => ...
-#  131|               0: [TupleExpr] (..., ...)
+#  131|               0: [TuplePatternExpr] (..., ...)
 #  131|                 0: [VariablePatternExpr] Int32 x
 #  131|                 1: [DiscardPatternExpr] _
 #  131|               2: [IntLiteral] 3

csharp/ql/test/library-tests/dataflow/tuples/PrintAst.expected

@@ -262,9 +262,9 @@ Tuples.cs:
 #   65|                   -1: [LocalVariableAccess] access to local variable t
 #   66|         4: [BreakStmt] break;
 #   67|         5: [CaseStmt] case ...:
-#   67|           0: [TupleExpr] (..., ...)
+#   67|           0: [TuplePatternExpr] (..., ...)
 #   67|             0: [VariablePatternExpr] String a
-#   67|             1: [TupleExpr] (..., ...)
+#   67|             1: [TuplePatternExpr] (..., ...)
 #   67|               0: [VariablePatternExpr] Int32 b
 #   67|               1: [VariablePatternExpr] String c
 #   67|             2: [DiscardPatternExpr] _
@@ -302,7 +302,7 @@ Tuples.cs:
 #   78|           0: [RecursivePatternExpr] { ... }
 #   78|             2: [PositionalPatternExpr] ( ... )
 #   78|               0: [VariablePatternExpr] String a
-#   78|               1: [TupleExpr] (..., ...)
+#   78|               1: [TuplePatternExpr] (..., ...)
 #   78|                 0: [VariablePatternExpr] Int32 b
 #   78|                 1: [VariablePatternExpr] String c
 #   78|               2: [DiscardPatternExpr] _
@@ -335,9 +335,9 @@ Tuples.cs:
 #   87|       7: [IfStmt] if (...) ...
 #   87|         0: [IsExpr] ... is ...
 #   87|           0: [LocalVariableAccess] access to local variable x
-#   87|           1: [TupleExpr] (..., ...)
+#   87|           1: [TuplePatternExpr] (..., ...)
 #   87|             0: [VariablePatternExpr] String p
-#   87|             1: [TupleExpr] (..., ...)
+#   87|             1: [TuplePatternExpr] (..., ...)
 #   87|               0: [VariablePatternExpr] Int32 q
 #   87|               1: [VariablePatternExpr] String r
 #   87|             2: [DiscardPatternExpr] _
@@ -417,7 +417,7 @@ Tuples.cs:
 #  107|       6: [SwitchStmt] switch (...) {...}
 #  107|         0: [LocalVariableAccess] access to local variable r
 #  109|         0: [CaseStmt] case ...:
-#  109|           0: [TupleExpr] (..., ...)
+#  109|           0: [TuplePatternExpr] (..., ...)
 #  109|             0: [VariablePatternExpr] String x
 #  109|             1: [VariablePatternExpr] Int32 y
 #  110|         1: [ExprStmt] ...;