bpo-41631: _ast module uses again a global state (#21961)
Partially revert commit ac46eb4ad6662cf6d771b20d8963658b2186c48c:
"bpo-38113: Update the Python-ast.c generator to PEP384 (gh-15957)".
Using a module state per module instance is causing subtle practical
problems.
For example, the Mercurial project replaces the __import__() function
to implement lazy import, whereas Python expected that "import _ast"
always return a fully initialized _ast module.
Add _PyAST_Fini() to clear the state at exit.
The _ast module has no state (set _astmodule.m_size to 0). Remove
astmodule_traverse(), astmodule_clear() and astmodule_free()
functions.
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index ab5a676..75d5780 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1259,6 +1259,12 @@
static void
finalize_interp_types(PyThreadState *tstate)
{
+ // The _ast module state is shared by all interpreters.
+ // The state must only be cleared by the main interpreter.
+ if (_Py_IsMainInterpreter(tstate)) {
+ _PyAST_Fini(tstate);
+ }
+
_PyExc_Fini(tstate);
_PyFrame_Fini(tstate);
_PyAsyncGen_Fini(tstate);