[rust2cpg] fix macro call expr returning multiple statements. (#6224)

Author: xavierpinho

joern-cli/frontends/rust2cpg/src/main/scala/io/joern/rust2cpg/astcreation/RustVisitor.scala

@@ -1643,11 +1643,9 @@ trait RustVisitor(implicit withSchemaValidation: ValidationMode) { this: AstCrea
   // MacroExpr =
   //  MacroCall
   private def visitMacroExpr(macroExpr: MacroExpr): Ast = {
-    // Even though it wraps a MacroCall, in this context it should always be a single expression, i.e.
-    // no MacroStmts/MacroItems. Logging just in case.
     visitMacroCall(macroExpr.macroCall) match {
       case exprAst :: Nil => exprAst
-      case _              => notHandledYet(macroExpr.macroCall)
+      case asts           => blockAst(blockNode(macroExpr), asts.toList)
     }
   }
 

joern-cli/frontends/rust2cpg/src/test/scala/io/joern/rust2cpg/passes/ast/MacroTests.scala

@@ -99,6 +99,47 @@ class MacroTests extends Rust2CpgSuite(noSysRoot = true) {
     }
   }
 
+  "macro call expression expanding to multiple statements" should {
+    val cpg = code("""
+        |macro_rules! three { () => { let mut s = 1; s += 2; s }; }
+        |fn main() {
+        | let x = { three!() };
+        |}
+        |""".stripMargin)
+
+    "have correct locals" in {
+      inside(cpg.local.sortBy(_.order).l) { case xLocal :: sLocal :: Nil =>
+        xLocal.name shouldBe "x"
+        xLocal.typeFullName shouldBe "i32"
+        sLocal.name shouldBe "s"
+        sLocal.typeFullName shouldBe "i32"
+      }
+    }
+
+    "have correct assignments" in {
+      cpg.method.nameExact("main").block.assignment.sortBy(_.order).code.l shouldBe List(
+        "let x = { three!() };",
+        "let mut s = 1;",
+        "s+=2"
+      )
+    }
+
+    "have correct children" in {
+      inside(cpg.method.nameExact("main").block.assignment.source.isBlock.astChildren.l) { case (three: Block) :: Nil =>
+        inside(three.astChildren.l) {
+          case (local: Local) :: (assign: Call) :: (assignPlus: Call) :: (ident: Identifier) :: Nil =>
+            local.name shouldBe "s"
+            assign.code shouldBe "let mut s = 1;"
+            assign.methodFullName shouldBe Operators.assignment
+            assignPlus.code shouldBe "s+=2"
+            assignPlus.methodFullName shouldBe Operators.assignmentPlus
+            ident.name shouldBe "s"
+            ident.typeFullName shouldBe "i32"
+        }
+      }
+    }
+  }
+
   "a type macro" should {
     val cpg = code("""
         |macro_rules! int_type { () => { i128 }; }