From 2bb70781e9c1d5a27b20b8e68980c19ec1ee25fb Mon Sep 17 00:00:00 2001
From: Jukka Lehtosalo <jukka.lehtosalo@iki.fi>
Date: Sun, 25 Jun 2023 10:22:00 +0100
Subject: [PATCH] [mypyc] Fix i16 on Python 3.12 (#15510)

Two recent mypyc PRs didn't work together (#15470 and #15464). Fix them.
---
 mypyc/lib-rt/int_ops.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/mypyc/lib-rt/int_ops.c b/mypyc/lib-rt/int_ops.c
index 2a118d99b5eb..528401692a3a 100644
--- a/mypyc/lib-rt/int_ops.c
+++ b/mypyc/lib-rt/int_ops.c
@@ -654,6 +654,18 @@ void CPyInt32_Overflow() {
 
 int16_t CPyLong_AsInt16(PyObject *o) {
     if (likely(PyLong_Check(o))) {
+    #if CPY_3_12_FEATURES
+        PyLongObject *lobj = (PyLongObject *)o;
+        size_t tag = CPY_LONG_TAG(lobj);
+        if (likely(tag == (1 << CPY_NON_SIZE_BITS))) {
+            // Fast path
+            digit x = CPY_LONG_DIGIT(lobj, 0);
+            if (x < 0x8000)
+                return x;
+        } else if (likely(tag == CPY_SIGN_ZERO)) {
+            return 0;
+        }
+    #else
         PyLongObject *lobj = (PyLongObject *)o;
         Py_ssize_t size = lobj->ob_base.ob_size;
         if (likely(size == 1)) {
@@ -664,6 +676,7 @@ int16_t CPyLong_AsInt16(PyObject *o) {
         } else if (likely(size == 0)) {
             return 0;
         }
+    #endif
     }
     // Slow path
     int overflow;