[lldb/Interpreter] Relax Scripted Interface object creation requirements

Historically, some scripted extension would pass the embedded
interpreter session dictionary as a argument of the extension
initializer.

In many cases, that argument ended up not being used but was still
required for all new extension implementations.

This patch relax this requirement by checking if the number of maximum
positional argument is 1 argument more then the number of argument
passed in the parameter pack, in which case it will pass the interpreter
session dictionary with the rest of the arguments. If the implementation
doesn't have it in the initializer, only the paramater pack is passed to it.

Signed-off-by: Med Ismail Bennani <[email protected]>

Author: medismailben

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedPythonInterface.h

@@ -180,12 +180,35 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
       llvm::Expected<PythonObject> expected_return_object =
           create_error("Resulting object is not initialized.");
 
-      std::apply(
-          [&init, &expected_return_object](auto &&...args) {
-            llvm::consumeError(expected_return_object.takeError());
-            expected_return_object = init(args...);
-          },
-          transformed_args);
+      // This relax the requirement on the number of argument for
+      // initializing scripting extension if the size of the interface
+      // parameter pack contains 1 less element than the extension maximum
+      // number of positional arguments for this initializer.
+      //
+      // This addresses the cases where the embedded interpreter session
+      // dictionary is passed to the extension initializer which is not used
+      // most of the time.
+      size_t num_args = sizeof...(Args);
+      if (num_args != arg_info->max_positional_args) {
+        if (num_args != arg_info->max_positional_args - 1)
+          return create_error("Passed arguments ({0}) doesn't match the number "
+                              "of expected arguments ({1}).",
+                              num_args, arg_info->max_positional_args);
+
+        std::apply(
+            [&init, &expected_return_object](auto &&...args) {
+              llvm::consumeError(expected_return_object.takeError());
+              expected_return_object = init(args...);
+            },
+            std::tuple_cat(transformed_args, std::make_tuple(dict)));
+      } else {
+        std::apply(
+            [&init, &expected_return_object](auto &&...args) {
+              llvm::consumeError(expected_return_object.takeError());
+              expected_return_object = init(args...);
+            },
+            transformed_args);
+      }
 
       if (!expected_return_object)
         return expected_return_object.takeError();

lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py

@@ -8,7 +8,7 @@
 
 
 class DummyStopHook:
-    def __init__(self, target, args, internal_dict):
+    def __init__(self, target, args):
         self.target = target
         self.args = args