fix: recognise joern_inner_buffer appends as erb calls

Author: Tebogo Selahle

joern-cli/frontends/rubysrc2cpg/src/main/scala/io/joern/rubysrc2cpg/astcreation/AstForExpressionsCreator.scala

@@ -185,9 +185,7 @@ trait AstForExpressionsCreator(implicit withSchemaValidation: ValidationMode) {
   protected def astForMemberCall(node: RubyCallWithBase, isStatic: Boolean = false): Ast = {
 
     def createMemberCall(n: RubyCallWithBase): Ast = {
-      val isErbCall = n.methodName == Constants.joernErbBufferAppend && n.arguments.headOption.exists(
-        _.span.text == "self.joern__buffer"
-      )
+      val isErbCall = n.methodName == Constants.joernErbBufferAppend
 
       val (nodeOp, hasStringArguments, receiverAst) = if (isErbCall) {
         val hasStringArgs = n.arguments.tail.exists {
@@ -325,7 +323,11 @@ trait AstForExpressionsCreator(implicit withSchemaValidation: ValidationMode) {
           scope.tryResolveTypeReference(x.typeName).map(_.name).getOrElse(Defines.Any)
       }
       .orElse(Option(Defines.Any))
-    val typeFullName = if node.memberName == "joern__buffer" then Constants.stringPrefix else Defines.Any
+    val typeFullName = if (node.memberName == "joern__buffer" || node.memberName == "joern__inner_buffer") {
+      Constants.stringPrefix
+    } else {
+      Defines.Any
+    }
     val fieldAccess = callNode(
       node,
       code,

joern-cli/frontends/rubysrc2cpg/src/test/scala/io/joern/rubysrc2cpg/querying/ErbTests.scala

@@ -261,9 +261,8 @@ class ErbTests extends RubyCode2CpgFixture {
           inside(lambdaMethod.body.astChildren.l) {
             case _ :: _ :: (appendCallTemplate: Call) :: _ :: _ :: Nil =>
               appendCallTemplate.code shouldBe "self.joern__buffer_append(joern__inner_buffer, <%= form.text_field :name %>)"
-              val List(selfId, appendCallArgOne, appendCallArgTwo: Call) = appendCallTemplate.argument.l: @unchecked
-              selfId.code shouldBe "self"
-
+              appendCallTemplate.methodFullName shouldBe "<operator>.joernBufferAppend"
+              val List(appendCallArgOne, appendCallArgTwo: Call) = appendCallTemplate.argument.l: @unchecked
               appendCallArgOne.code shouldBe "joern__inner_buffer"
               appendCallArgTwo.code shouldBe "<%= form.text_field :name %>"
               appendCallArgTwo.methodFullName shouldBe RubyOperators.templateOutEscape