[c#] Ast for foreach statements (joernio#4072)

This PR includes,

1. Upgrading to new `DotNetAstGen` version.
2. AST Creation for `foreach` statements.
3. Tests for `foreach` statements.
4. Type Mapping for `PredefinedType` node.

Resolves joernio#3986

joern-cli/frontends/csharpsrc2cpg/src/main/resources/application.conf

@@ -1,3 +1,3 @@
 csharpsrc2cpg {
-    dotnetastgen_version: "0.14.0"
+    dotnetastgen_version: "0.15.0"
 }

joern-cli/frontends/csharpsrc2cpg/src/main/scala/io/joern/csharpsrc2cpg/astcreation/AstCreatorHelper.scala

@@ -73,6 +73,8 @@ trait AstCreatorHelper(implicit withSchemaValidation: ValidationMode) { this: As
       case IdentifierName                                 =>
         // TODO: Look at scope object for possible types
         Defines.Any
+      case PredefinedType =>
+        BuiltinTypes.DotNetTypeMap.getOrElse(node.code, Defines.Any)
       case _ =>
         Try(createDotNetNodeInfo(node.json(ParserKeys.Type))) match
           case Success(typeNode) =>

joern-cli/frontends/csharpsrc2cpg/src/main/scala/io/joern/csharpsrc2cpg/astcreation/AstForStatementsCreator.scala

@@ -4,13 +4,15 @@ import io.circe.Json
 import io.joern.csharpsrc2cpg.parser.DotNetJsonAst.{
   BinaryExpr,
   Block,
+  ExpressionStatement,
+  ForEachStatement,
   GlobalStatement,
   IfStatement,
   LiteralExpr,
+  ThrowStatement,
+  TryStatement,
   UnaryExpr
 }
-import io.joern.csharpsrc2cpg.parser.DotNetJsonAst.{ExpressionStatement, GlobalStatement, ThrowStatement, TryStatement}
-import io.circe.Json
 import io.joern.csharpsrc2cpg.parser.DotNetJsonAst.{
   BinaryExpr,
   Block,
@@ -54,9 +56,29 @@ trait AstForStatementsCreator(implicit withSchemaValidation: ValidationMode) { t
       case IfStatement         => astForIfStatement(nodeInfo)
       case ThrowStatement      => astForThrowStatement(nodeInfo)
       case TryStatement        => astForTryStatement(nodeInfo)
+      case ForEachStatement    => astForForEachStatement(nodeInfo)
       case _                   => notHandledYet(nodeInfo)
   }
 
+  private def astForForEachStatement(forEachStmt: DotNetNodeInfo): Seq[Ast] = {
+    val forEachNode     = controlStructureNode(forEachStmt, ControlStructureTypes.FOR, forEachStmt.code)
+    val iterableAst     = astForNode(forEachStmt.json(ParserKeys.Expression))
+    val forEachBlockAst = astForBlock(createDotNetNodeInfo(forEachStmt.json(ParserKeys.Statement)))
+
+    val identifierValue = forEachStmt.json(ParserKeys.Identifier)(ParserKeys.Value).str
+    val _identifierNode =
+      identifierNode(
+        node = createDotNetNodeInfo(forEachStmt.json(ParserKeys.Type)),
+        name = identifierValue,
+        code = identifierValue,
+        typeFullName = nodeTypeFullName(createDotNetNodeInfo(forEachStmt.json(ParserKeys.Type)))
+      )
+
+    val iteratorVarAst = Ast(_identifierNode)
+
+    Seq(Ast(forEachNode).withChild(iteratorVarAst).withChildren(iterableAst).withChild(forEachBlockAst))
+  }
+
   private def astForElseStatement(elseParserNode: DotNetNodeInfo): Ast = {
     val elseNode = controlStructureNode(elseParserNode, ControlStructureTypes.ELSE, "else")
 

joern-cli/frontends/csharpsrc2cpg/src/main/scala/io/joern/csharpsrc2cpg/parser/DotNetJsonAst.scala

@@ -146,6 +146,8 @@ object DotNetJsonAst {
 
   object FinallyClause extends ClauseExpr
 
+  object ForEachStatement extends BaseStmt
+
 }
 
 /** The JSON key values, in alphabetical order.

joern-cli/frontends/csharpsrc2cpg/src/test/scala/io/joern/csharpsrc2cpg/querying/ast/LoopsTests.scala

@@ -0,0 +1,43 @@
+package io.joern.csharpsrc2cpg.querying.ast
+
+import io.joern.csharpsrc2cpg.testfixtures.CSharpCode2CpgFixture
+import io.shiftleft.codepropertygraph.generated.ControlStructureTypes
+import io.shiftleft.semanticcpg.language.*
+
+class LoopsTests extends CSharpCode2CpgFixture {
+  "AST Creation for loops" should {
+    "be correct for foreach statement" in {
+      val cpg = code(basicBoilerplate("""
+          |List<int> fibNumbers = [0, 1, 1, 2, 3, 5, 8, 13];
+          |foreach (int element in fibNumbers)
+          |{
+          |    Console.Write($"{element} ");
+          |}
+          |""".stripMargin))
+
+      inside(cpg.method("Main").controlStructure.l) {
+        case forEachNode :: Nil =>
+          forEachNode.controlStructureType shouldBe ControlStructureTypes.FOR
+
+          inside(forEachNode.astChildren.isIdentifier.l) {
+            case iteratorNode :: iterableNode :: Nil =>
+              iteratorNode.code shouldBe "element"
+              iteratorNode.typeFullName shouldBe "System.Int32"
+
+              iterableNode.code shouldBe "fibNumbers"
+              iterableNode.typeFullName shouldBe "List<int>"
+            case _ => fail("No node for iterable found in `foreach` statement")
+          }
+
+          inside(forEachNode.astChildren.isBlock.l) {
+            case blockNode :: Nil =>
+              val List(writeCall) = cpg.call.nameExact("Write").l
+              writeCall.astParent shouldBe blockNode
+            case _ => fail("Correct blockNode as child not found for `foreach` statement")
+          }
+
+        case _ => fail("No control structure node found for `foreach`.")
+      }
+    }
+  }
+}