From 70856f126dd415e310e807c82edad24f4d0778ce Mon Sep 17 00:00:00 2001
From: Sam Gross <colesbury@gmail.com>
Date: Tue, 7 Jul 2020 13:41:47 -0400
Subject: [PATCH] asdl: use _PyOnceFlag in Python-ast.c

---
 Include/internal/pycore_ast_state.h | 1 +
 Parser/asdl_c.py                    | 9 +++++++--
 Python/Python-ast.c                 | 8 ++++++--
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Include/internal/pycore_ast_state.h b/Include/internal/pycore_ast_state.h
index f15b4905eed..9c4de1d50b2 100644
--- a/Include/internal/pycore_ast_state.h
+++ b/Include/internal/pycore_ast_state.h
@@ -12,6 +12,7 @@ extern "C" {
 
 struct ast_state {
     int initialized;
+    _PyOnceFlag once;
     int recursion_depth;
     int recursion_limit;
     PyObject *AST_type;
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 3e307610b63..37f01b14d8f 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -1467,6 +1467,7 @@ def visit(self, object):
 def generate_ast_state(module_state, f):
     f.write('struct ast_state {\n')
     f.write('    int initialized;\n')
+    f.write('    _PyOnceFlag once;\n')
     f.write('    int recursion_depth;\n')
     f.write('    int recursion_limit;\n')
     for s in module_state:
@@ -1544,8 +1545,12 @@ def generate_module_def(mod, metadata, f, internal_h):
         {
             PyInterpreterState *interp = _PyInterpreterState_GET();
             struct ast_state *state = &interp->ast;
-            if (!init_types(state)) {
-                return NULL;
+            if (_PyBeginOnce(&state->once)) {
+                if (!init_types(state)) {
+                    _PyEndOnceFailed(&state->once);
+                    return NULL;
+                }
+                _PyEndOnce(&state->once);
             }
             return state;
         }
diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index d113c47b953..1e30227a8a0 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -17,8 +17,12 @@ get_ast_state(void)
 {
     PyInterpreterState *interp = _PyInterpreterState_GET();
     struct ast_state *state = &interp->ast;
-    if (!init_types(state)) {
-        return NULL;
+    if (_PyBeginOnce(&state->once)) {
+        if (!init_types(state)) {
+            _PyEndOnceFailed(&state->once);
+            return NULL;
+        }
+        _PyEndOnce(&state->once);
     }
     return state;
 }