Fix segmentation fault on Python 3.13

.github/workflows/ci.yml

@@ -60,8 +60,7 @@ jobs:
         - "3.10"
         - "3.11"
         - "3.12"
-        # TODO: Enable this once fixed https://github.com/jcrist/msgspec/issues/910
-        # - "3.13"
+        - "3.13"
         - "3.14"
 
     steps:

src/msgspec/_core.c

@@ -23,6 +23,11 @@
 #define PY313_PLUS (PY_VERSION_HEX >= 0x030d0000)
 #define PY314_PLUS (PY_VERSION_HEX >= 0x030e0000)
 
+#if PY313_PLUS && !PY314_PLUS
+    #define Py_BUILD_CORE
+    #include "internal/pycore_frame.h"
+#endif
+
 /* Hint to the compiler not to store `x` in a register since it is likely to
  * change. Results in much higher performance on GCC, with smaller benefits on
  * clang */
@@ -5337,6 +5342,11 @@ Struct_alloc(PyTypeObject *type) {
     if (obj == NULL) return NULL;
     /* Zero out slot fields */
     memset((char *)obj + sizeof(PyObject), '\0', type->tp_basicsize - sizeof(PyObject));
+#if PY313_PLUS && !PY314_PLUS
+    if (type->tp_flags & Py_TPFLAGS_INLINE_VALUES) {
+        _PyObject_InitInlineValues(obj, type);
+    }
+#endif
     return obj;
 }