[lldb] Make Python >= 3.8 required for LLDB 21 (#124735)

As decided on
https://discourse.llvm.org/t/rfc-lets-document-and-enforce-a-minimum-python-version-for-lldb/82731.

LLDB 20 recommended `>= 3.8` but did not remove support for anything
earlier. Now we are in what will become LLDB 21, so I'm removing that
support and making
`>= 3.8` required.

See https://docs.python.org/3/c-api/apiabiversion.html#c.PY_VERSION_HEX
for the format of PY_VERSION_HEX.

3 files changed, 4 insertions, 86 deletions

diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
index a0f8cf9..1340425 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
@@ -73,10 +73,8 @@ Expected<std::string> python::As<std::string>(Expected<PythonObject> &&obj) {
 static bool python_is_finalizing() {
 #if PY_VERSION_HEX >= 0x030d0000
   return Py_IsFinalizing();
-#elif PY_VERSION_HEX >= 0x03070000
-  return _Py_IsFinalizing();
 #else
-  return _Py_Finalizing != nullptr;
+  return _Py_IsFinalizing();
 #endif
 }
 
@@ -810,7 +808,6 @@ bool PythonCallable::Check(PyObject *py_obj) {
   return PyCallable_Check(py_obj);
 }
 
-#if PY_VERSION_HEX >= 0x03030000
 static const char get_arg_info_script[] = R"(
 from inspect import signature, Parameter, ismethod
 from collections import namedtuple
@@ -832,15 +829,12 @@ def main(f):
             raise Exception(f'unknown parameter kind: {kind}')
     return ArgInfo(count, varargs)
 )";
-#endif
 
 Expected<PythonCallable::ArgInfo> PythonCallable::GetArgInfo() const {
   ArgInfo result = {};
   if (!IsValid())
     return nullDeref();
 
-#if PY_VERSION_HEX >= 0x03030000
-
   // no need to synchronize access to this global, we already have the GIL
   static PythonScript get_arg_info(get_arg_info_script);
   Expected<PythonObject> pyarginfo = get_arg_info(*this);
@@ -852,57 +846,6 @@ Expected<PythonCallable::ArgInfo> PythonCallable::GetArgInfo() const {
       cantFail(As<bool>(pyarginfo.get().GetAttribute("has_varargs")));
   result.max_positional_args = has_varargs ? ArgInfo::UNBOUNDED : count;
 
-#else
-  PyObject *py_func_obj;
-  bool is_bound_method = false;
-  bool is_class = false;
-
-  if (PyType_Check(m_py_obj) || PyClass_Check(m_py_obj)) {
-    auto init = GetAttribute("__init__");
-    if (!init)
-      return init.takeError();
-    py_func_obj = init.get().get();
-    is_class = true;
-  } else {
-    py_func_obj = m_py_obj;
-  }
-
-  if (PyMethod_Check(py_func_obj)) {
-    py_func_obj = PyMethod_GET_FUNCTION(py_func_obj);
-    PythonObject im_self = GetAttributeValue("im_self");
-    if (im_self.IsValid() && !im_self.IsNone())
-      is_bound_method = true;
-  } else {
-    // see if this is a callable object with an __call__ method
-    if (!PyFunction_Check(py_func_obj)) {
-      PythonObject __call__ = GetAttributeValue("__call__");
-      if (__call__.IsValid()) {
-        auto __callable__ = __call__.AsType<PythonCallable>();
-        if (__callable__.IsValid()) {
-          py_func_obj = PyMethod_GET_FUNCTION(__callable__.get());
-          PythonObject im_self = __callable__.GetAttributeValue("im_self");
-          if (im_self.IsValid() && !im_self.IsNone())
-            is_bound_method = true;
-        }
-      }
-    }
-  }
-
-  if (!py_func_obj)
-    return result;
-
-  PyCodeObject *code = (PyCodeObject *)PyFunction_GET_CODE(py_func_obj);
-  if (!code)
-    return result;
-
-  auto count = code->co_argcount;
-  bool has_varargs = !!(code->co_flags & CO_VARARGS);
-  result.max_positional_args =
-      has_varargs ? ArgInfo::UNBOUNDED
-                  : (count - (int)is_bound_method) - (int)is_class;
-
-#endif
-
   return result;
 }
 
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
index ef3c53c..e78e606 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -70,8 +70,7 @@ extern "C" PyObject *PyInit__lldb(void);
 // Don't mess with the signal handlers on Windows.
 #define LLDB_USE_PYTHON_SET_INTERRUPT 0
 #else
-// PyErr_SetInterrupt was introduced in 3.2.
-#define LLDB_USE_PYTHON_SET_INTERRUPT PY_VERSION_HEX >= 0x03020000
+#define LLDB_USE_PYTHON_SET_INTERRUPT 1
 #endif
 
 static ScriptInterpreterPythonImpl *GetPythonInterpreter(Debugger &debugger) {
@@ -91,10 +90,8 @@ namespace {
 struct InitializePythonRAII {
 public:
   InitializePythonRAII() {
-#if PY_VERSION_HEX >= 0x03080000
     PyConfig config;
     PyConfig_InitPythonConfig(&config);
-#endif
 
 #if LLDB_EMBED_PYTHON_HOME
     static std::string g_python_home = []() -> std::string {
@@ -108,14 +105,7 @@ public:
       return spec.GetPath();
     }();
     if (!g_python_home.empty()) {
-#if PY_VERSION_HEX >= 0x03080000
       PyConfig_SetBytesString(&config, &config.home, g_python_home.c_str());
-#else
-      size_t size = 0;
-      wchar_t *python_home_w = Py_DecodeLocale(g_python_home.c_str(), &size);
-      Py_SetPythonHome(python_home_w);
-      PyMem_RawFree(python_home_w);
-#endif
     }
 #endif
 
@@ -142,23 +132,10 @@ public:
       PyImport_AppendInittab("_lldb", LLDBSwigPyInit);
     }
 
-#if PY_VERSION_HEX >= 0x03080000
     config.install_signal_handlers = 0;
     Py_InitializeFromConfig(&config);
     PyConfig_Clear(&config);
     InitializeThreadsPrivate();
-#else
-// Python < 3.2 and Python >= 3.2 reversed the ordering requirements for
-// calling `Py_Initialize` and `PyEval_InitThreads`.  < 3.2 requires that you
-// call `PyEval_InitThreads` first, and >= 3.2 requires that you call it last.
-#if PY_VERSION_HEX >= 0x03020000
-    Py_InitializeEx(0);
-    InitializeThreadsPrivate();
-#else
-    InitializeThreadsPrivate();
-    Py_InitializeEx(0);
-#endif
-#endif
   }
 
   ~InitializePythonRAII() {
@@ -181,11 +158,9 @@ private:
 // would always return `true` and `PyGILState_Ensure/Release` flow would be
 // executed instead of unlocking GIL with `PyEval_SaveThread`. When
 // an another thread calls `PyGILState_Ensure` it would get stuck in deadlock.
-#if PY_VERSION_HEX >= 0x03070000
     // The only case we should go further and acquire the GIL: it is unlocked.
     if (PyGILState_Check())
       return;
-#endif
 
 // `PyEval_ThreadsInitialized` was deprecated in Python 3.9 and removed in
 // Python 3.13. It has been returning `true` always since Python 3.7.
diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/lldb-python.h b/lldb/source/Plugins/ScriptInterpreter/Python/lldb-python.h
index b68598b..4a6c11d 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/lldb-python.h
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/lldb-python.h
@@ -50,8 +50,8 @@ static llvm::Expected<bool> *g_fcxx_modules_workaround [[maybe_unused]];
 
 // Provide a meaningful diagnostic error if someone tries to compile this file
 // with a version of Python we don't support.
-static_assert(PY_VERSION_HEX >= 0x03000000,
-              "LLDB requires at least Python 3.0");
+static_assert(PY_VERSION_HEX >= 0x03080000,
+              "LLDB requires at least Python 3.8");
 #endif
 
 #endif // LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_LLDB_PYTHON_H