From 733d38c1085288af11e975cb40ec2e3cc7619e6d Mon Sep 17 00:00:00 2001
From: slow-but-steady <slowbutsteady1234@gmail.com>
Date: Tue, 25 Jul 2023 18:46:30 -0700
Subject: [PATCH] Add missing `<stddef.h>` to included files in
 `Modules/zlibmodule.c`
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Recent CI builds are failing because the `offsetof` function in
`Modules/zlibmodule.c` cannot be called. For example, see
https://buildbot.python.org/all/#/builders/15/builds/5217/steps/4/logs/stdio
from commit fabcbe9c12688eb9a902a5c89cb720ed373625c5. Here is a relevant
snippet from the stdio logs for step 4 compile:

```
../Modules/zlibmodule.c:1802:21: error: implicit declaration of function ‘offsetof’ [-Werror=implicit-function-declaration]
 #define COMP_OFF(x) offsetof(compobject, x)
                     ^~~~~~~~
../Modules/zlibmodule.c:1804:39: note: in expansion of macro ‘COMP_OFF’
     {"unused_data",     _Py_T_OBJECT, COMP_OFF(unused_data), Py_READONLY},
                                       ^~~~~~~~
../Modules/zlibmodule.c:1802:21: note: ‘offsetof’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
../Modules/zlibmodule.c:1776:1:
+#include <stddef.h>

../Modules/zlibmodule.c:1802:21:
 #define COMP_OFF(x) offsetof(compobject, x)
                     ^~~~~~~~
../Modules/zlibmodule.c:1804:39: note: in expansion of macro ‘COMP_OFF’
     {"unused_data",     _Py_T_OBJECT, COMP_OFF(unused_data), Py_READONLY},
                                       ^~~~~~~~
../Modules/zlibmodule.c:1802:30: error: expected expression before ‘compobject’
 #define COMP_OFF(x) offsetof(compobject, x)
                              ^~~~~~~~~~
```
---
 Modules/zlibmodule.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 22da50989a88dc..a98a37adadcff0 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -7,6 +7,7 @@
 
 #include "zlib.h"
 #include "stdbool.h"
+#include <stddef.h>               // offsetof()
 
 #if defined(ZLIB_VERNUM) && ZLIB_VERNUM < 0x1221
 #error "At least zlib version 1.2.2.1 is required"