Open a block and function scope for python functions (#1731)

cpg-language-python/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/python/StatementHandler.kt

@@ -397,7 +397,12 @@ class StatementHandler(frontend: PythonLanguageFrontend) :
         handleArguments(s.args, result, recordDeclaration)
 
         if (s.body.isNotEmpty()) {
-            result.body = makeBlock(s.body, parentNode = s)
+            // Make sure we open a new (block) scope for the function body. This is not a 1:1
+            // mapping to python scopes, since python only has a "function scope", but in the CPG
+            // the function scope only comprises the function arguments, and we need a block scope
+            // to
+            // hold all local variables within the function body.
+            result.body = makeBlock(s.body, parentNode = s, enterScope = true)
         }
 
         frontend.scopeManager.leaveScope(result)
@@ -603,16 +608,29 @@ class StatementHandler(frontend: PythonLanguageFrontend) :
      * This function "wraps" a list of [Python.AST.BaseStmt] nodes into a [Block]. Since the list
      * itself does not have a code/location, we need to employ [codeAndLocationFromChildren] on the
      * [parentNode].
+     *
+     * Optionally, a new scope will be opened when [enterScope] is specified. This should be done
+     * VERY carefully, as Python has a very limited set of scopes and is most likely only to be used
+     * by [handleFunctionDef].
      */
     private fun makeBlock(
         stmts: List<Python.AST.BaseStmt>,
-        parentNode: Python.AST.WithLocation
+        parentNode: Python.AST.WithLocation,
+        enterScope: Boolean = false,
     ): Block {
         val result = newBlock()
+        if (enterScope) {
+            frontend.scopeManager.enterScope(result)
+        }
+
         for (stmt in stmts) {
             result.statements += handle(stmt)
         }
 
+        if (enterScope) {
+            frontend.scopeManager.leaveScope(result)
+        }
+
         // Try to retrieve the code and location from the parent node, if it is a base stmt
         var baseStmt = parentNode as? Python.AST.BaseStmt
         return if (baseStmt != null) {