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Author: AA-Turner

Modules/_zstd/_zstdmodule.c

@@ -679,7 +679,7 @@ do {                                                                         \
     ADD_INT_CONST_TO_TYPE(mod_state->ZstdCompressor_type,
                           "FLUSH_FRAME", ZSTD_e_end);
 
-    /* Make ZstdCompressor immutable */
+    /* Make ZstdCompressor immutable (set Py_TPFLAGS_IMMUTABLETYPE) */
     PyType_Freeze(mod_state->ZstdCompressor_type);
 
 #undef ADD_TYPE

Modules/_zstd/compressor.c

@@ -729,6 +729,9 @@ static PyType_Slot zstdcompressor_slots[] = {
 PyType_Spec zstd_compressor_type_spec = {
     .name = "compression.zstd.ZstdCompressor",
     .basicsize = sizeof(ZstdCompressor),
+    // Py_TPFLAGS_IMMUTABLETYPE is not used here as several
+    // associated constants need to be added to the type.
+    // PyType_Freeze is called later to set the flag.
     .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
     .slots = zstdcompressor_slots,
 };