provisional fix to compile on windows

Author: tom-pytel

Include/internal/pycore_pyatomic_ft_wrappers.h

@@ -110,9 +110,11 @@ extern "C" {
 #define FT_ATOMIC_LOAD_ULLONG_RELAXED(value) \
     _Py_atomic_load_ullong_relaxed(&value)
 
+// This should probably be moved into its own file as a real function.
 static inline void *
-FT_ATOMIC_MEMCPY_PTR_RELAXED(void *dest, void *src, ssize_t n)
+_Py_atomic_memcpy_ptr_relaxed(void *dest, void *src, Py_ssize_t sn)
 {
+    size_t n = (size_t)sn;
     assert(((uintptr_t)dest & (sizeof (void *) - 1)) == 0);
     assert(((uintptr_t)src & (sizeof (void *) - 1)) == 0);
     assert(n % sizeof(void *) == 0);
@@ -127,9 +129,13 @@ FT_ATOMIC_MEMCPY_PTR_RELAXED(void *dest, void *src, ssize_t n)
     return dest;
 }
 
+#define FT_ATOMIC_MEMCPY_PTR_RELAXED(dest, src, n) \
+    _Py_atomic_memcpy_ptr_relaxed(dest, src, (Py_ssize_t)(n))
+
 static inline void *
-FT_ATOMIC_MEMMOVE_PTR_RELAXED(void *dest, void *src, ssize_t n)
+_Py_atomic_memmove_ptr_relaxed(void *dest, void *src, Py_ssize_t sn)
 {
+    size_t n = (size_t)sn;
     assert(((uintptr_t)dest & (sizeof (void *) - 1)) == 0);
     assert(((uintptr_t)src & (sizeof (void *) - 1)) == 0);
     assert(n % sizeof(void *) == 0);
@@ -151,6 +157,9 @@ FT_ATOMIC_MEMMOVE_PTR_RELAXED(void *dest, void *src, ssize_t n)
     return dest;
 }
 
+#define FT_ATOMIC_MEMMOVE_PTR_RELAXED(dest, src, n) \
+    _Py_atomic_memmove_ptr_relaxed(dest, src, (Py_ssize_t)(n))
+
 
 #else
 #define FT_ATOMIC_LOAD_PTR(value) value