Several CAPI tests include `<stddef.h>` for no reason

[sobolevn]

Bug report

These files do not use offset or ptrdiff_t that some files use:

diff --git Modules/_testcapi/abstract.c Modules/_testcapi/abstract.c
index 81a3dea4c1d..a93477a7090 100644
--- Modules/_testcapi/abstract.c
+++ Modules/_testcapi/abstract.c
@@ -1,5 +1,3 @@
-#include <stddef.h> // ptrdiff_t
-
 #include "parts.h"
 #include "util.h"
 
diff --git Modules/_testcapi/dict.c Modules/_testcapi/dict.c
index 810989fbed8..5f6a1a037dc 100644
--- Modules/_testcapi/dict.c
+++ Modules/_testcapi/dict.c
@@ -1,5 +1,3 @@
-#include <stddef.h> // ptrdiff_t
-
 #include "parts.h"
 #include "util.h"
 
diff --git Modules/_testcapi/set.c Modules/_testcapi/set.c
index f68a1859698..35e686e1e29 100644
--- Modules/_testcapi/set.c
+++ Modules/_testcapi/set.c
@@ -1,5 +1,3 @@
-#include <stddef.h> // ptrdiff_t
-
 #include "parts.h"
 #include "util.h"
 

I suggest removing them.

Linked PRs

• gh-110549: Remove unused includes of <stddef.h> #110552
• [3.12] gh-110549: Remove unused includes of <stddef.h> in _testcapi (GH-110552) #110553