From 9193efdeab4596f987528ba278afa2eca93a9e8a Mon Sep 17 00:00:00 2001
From: Petr Viktorin <encukou@gmail.com>
Date: Thu, 26 Jun 2025 11:48:37 +0200
Subject: [PATCH] gh-125206: Make _Py_FFI_SUPPORT_C_COMPLEX private (GH-135932)

---
 Modules/_ctypes/_ctypes_test.c | 4 ++--
 Modules/_ctypes/cfield.c       | 4 ++--
 Modules/_ctypes/ctypes.h       | 2 +-
 configure                      | 2 +-
 configure.ac                   | 2 +-
 pyconfig.h.in                  | 6 +++---
 6 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/Modules/_ctypes/_ctypes_test.c b/Modules/_ctypes/_ctypes_test.c
index d28e5708b44..66338805007 100644
--- a/Modules/_ctypes/_ctypes_test.c
+++ b/Modules/_ctypes/_ctypes_test.c
@@ -23,7 +23,7 @@
 #  define _Py_thread_local __thread
 #endif
 
-#if defined(Py_FFI_SUPPORT_C_COMPLEX)
+#if defined(_Py_FFI_SUPPORT_C_COMPLEX)
 #  include <complex.h>            // csqrt()
 #  undef I                        // for _ctypes_test_generated.c.h
 #endif
@@ -457,7 +457,7 @@ EXPORT(double) my_sqrt(double a)
     return sqrt(a);
 }
 
-#if defined(Py_FFI_SUPPORT_C_COMPLEX)
+#if defined(_Py_FFI_SUPPORT_C_COMPLEX)
 EXPORT(double complex) my_csqrt(double complex a)
 {
     return csqrt(a);
diff --git a/Modules/_ctypes/cfield.c b/Modules/_ctypes/cfield.c
index 163b9264261..547e2471a1c 100644
--- a/Modules/_ctypes/cfield.c
+++ b/Modules/_ctypes/cfield.c
@@ -759,7 +759,7 @@ d_get(void *ptr, Py_ssize_t size)
     return PyFloat_FromDouble(val);
 }
 
-#if defined(Py_FFI_SUPPORT_C_COMPLEX)
+#if defined(_Py_FFI_SUPPORT_C_COMPLEX)
 
 /* We don't use _Complex types here, using arrays instead, as the C11+
    standard says: "Each complex type has the same representation and alignment
@@ -1599,7 +1599,7 @@ for base_code, base_c_type in [
     ///////////////////////////////////////////////////////////////////////////
 
     TABLE_ENTRY_SW(d, &ffi_type_double);
-#if defined(Py_FFI_SUPPORT_C_COMPLEX)
+#if defined(_Py_FFI_SUPPORT_C_COMPLEX)
     if (Py_FFI_COMPLEX_AVAILABLE) {
         TABLE_ENTRY(D, &ffi_type_complex_double);
         TABLE_ENTRY(F, &ffi_type_complex_float);
diff --git a/Modules/_ctypes/ctypes.h b/Modules/_ctypes/ctypes.h
index 6a45c11e61a..5b4f97d43b8 100644
--- a/Modules/_ctypes/ctypes.h
+++ b/Modules/_ctypes/ctypes.h
@@ -23,7 +23,7 @@
 
 // Do we support C99 complex types in ffi?
 // For Apple's libffi, this must be determined at runtime (see gh-128156).
-#if defined(Py_FFI_SUPPORT_C_COMPLEX)
+#if defined(_Py_FFI_SUPPORT_C_COMPLEX)
 #   if USING_APPLE_OS_LIBFFI && defined(__has_builtin)
 #       if __has_builtin(__builtin_available)
 #           define Py_FFI_COMPLEX_AVAILABLE __builtin_available(macOS 10.15, *)
diff --git a/configure b/configure
index 50223d81cd9..43b36d9231e 100755
--- a/configure
+++ b/configure
@@ -15742,7 +15742,7 @@ fi
 printf "%s\n" "$ac_cv_ffi_complex_double_supported" >&6; }
 if test "$ac_cv_ffi_complex_double_supported" = "yes"; then
 
-printf "%s\n" "#define Py_FFI_SUPPORT_C_COMPLEX 1" >>confdefs.h
+printf "%s\n" "#define _Py_FFI_SUPPORT_C_COMPLEX 1" >>confdefs.h
 
 fi
 
diff --git a/configure.ac b/configure.ac
index f58e16c774f..e77696e3a4e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4163,7 +4163,7 @@ int main(void)
 [ac_cv_ffi_complex_double_supported=no])
 ])])
 if test "$ac_cv_ffi_complex_double_supported" = "yes"; then
-    AC_DEFINE([Py_FFI_SUPPORT_C_COMPLEX], [1],
+    AC_DEFINE([_Py_FFI_SUPPORT_C_COMPLEX], [1],
               [Defined if _Complex C type can be used with libffi.])
 fi
 
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 65a2c55217c..d4f1da7fb10 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -1736,9 +1736,6 @@
 /* Defined if Python is built as a shared library. */
 #undef Py_ENABLE_SHARED
 
-/* Defined if _Complex C type can be used with libffi. */
-#undef Py_FFI_SUPPORT_C_COMPLEX
-
 /* Define if you want to disable the GIL */
 #undef Py_GIL_DISABLED
 
@@ -2026,6 +2023,9 @@
 /* Maximum length in bytes of a thread name */
 #undef _PYTHREAD_NAME_MAXLEN
 
+/* Defined if _Complex C type can be used with libffi. */
+#undef _Py_FFI_SUPPORT_C_COMPLEX
+
 /* Define to force use of thread-safe errno, h_errno, and other functions */
 #undef _REENTRANT