[libc++] Remove <stddef.h> includes from the granularized <cstddef> headers (#114788)
We can define some of these aliases without having to include the system
<stddef.h> and there doesn't seem to be much of a reason we shouldn't do
it this way.
GitOrigin-RevId: 5acc4a3dc0e2145d2bfef47f1543bb291c2b866a
diff --git a/include/__cstddef/nullptr_t.h b/include/__cstddef/nullptr_t.h
index de3f7d4..7eaae01 100644
--- a/include/__cstddef/nullptr_t.h
+++ b/include/__cstddef/nullptr_t.h
@@ -10,7 +10,6 @@
#define _LIBCPP___CSTDDEF_NULLPTR_T_H
#include <__config>
-#include <stddef.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
@@ -18,7 +17,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-using ::nullptr_t;
+using nullptr_t = decltype(nullptr);
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__cstddef/ptrdiff_t.h b/include/__cstddef/ptrdiff_t.h
index f8b5cda..146f345 100644
--- a/include/__cstddef/ptrdiff_t.h
+++ b/include/__cstddef/ptrdiff_t.h
@@ -10,7 +10,6 @@
#define _LIBCPP___CSTDDEF_PTRDIFF_T_H
#include <__config>
-#include <stddef.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
@@ -18,7 +17,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-using ::ptrdiff_t _LIBCPP_USING_IF_EXISTS;
+using ptrdiff_t = decltype(static_cast<int*>(nullptr) - static_cast<int*>(nullptr));
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__cstddef/size_t.h b/include/__cstddef/size_t.h
index 91abbf0..59bad93 100644
--- a/include/__cstddef/size_t.h
+++ b/include/__cstddef/size_t.h
@@ -10,7 +10,6 @@
#define _LIBCPP___CSTDDEF_SIZE_T_H
#include <__config>
-#include <stddef.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
@@ -18,7 +17,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-using ::size_t _LIBCPP_USING_IF_EXISTS;
+using size_t = decltype(sizeof(int));
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__exception/exception_ptr.h b/include/__exception/exception_ptr.h
index 32c56fc..c43c005 100644
--- a/include/__exception/exception_ptr.h
+++ b/include/__exception/exception_ptr.h
@@ -10,6 +10,7 @@
#define _LIBCPP___EXCEPTION_EXCEPTION_PTR_H
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__exception/operations.h>
#include <__memory/addressof.h>
#include <__memory/construct_at.h>
diff --git a/include/__functional/function.h b/include/__functional/function.h
index e3844f8..543be05 100644
--- a/include/__functional/function.h
+++ b/include/__functional/function.h
@@ -12,6 +12,7 @@
#include <__assert>
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__exception/exception.h>
#include <__functional/binary_function.h>
#include <__functional/invoke.h>
diff --git a/include/__functional/hash.h b/include/__functional/hash.h
index 87009df..a33cba5 100644
--- a/include/__functional/hash.h
+++ b/include/__functional/hash.h
@@ -10,6 +10,7 @@
#define _LIBCPP___FUNCTIONAL_HASH_H
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__functional/unary_function.h>
#include <__fwd/functional.h>
#include <__type_traits/conjunction.h>
diff --git a/include/__memory/shared_ptr.h b/include/__memory/shared_ptr.h
index 31650a5..1527c01 100644
--- a/include/__memory/shared_ptr.h
+++ b/include/__memory/shared_ptr.h
@@ -13,6 +13,7 @@
#include <__compare/compare_three_way.h>
#include <__compare/ordering.h>
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__cstddef/ptrdiff_t.h>
#include <__exception/exception.h>
#include <__functional/binary_function.h>
diff --git a/include/forward_list b/include/forward_list
index 04466d9..a511fef 100644
--- a/include/forward_list
+++ b/include/forward_list
@@ -200,6 +200,7 @@
#include <__algorithm/lexicographical_compare_three_way.h>
#include <__algorithm/min.h>
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__iterator/distance.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/move_iterator.h>
diff --git a/include/new b/include/new
index 5318ce5..49e5008 100644
--- a/include/new
+++ b/include/new
@@ -87,6 +87,7 @@
*/
#include <__config>
+#include <__cstddef/max_align_t.h>
#include <__cstddef/size_t.h>
#include <__exception/exception.h>
#include <__type_traits/is_function.h>
diff --git a/include/string_view b/include/string_view
index 0edda7a..db1f425 100644
--- a/include/string_view
+++ b/include/string_view
@@ -208,6 +208,7 @@
#include <__algorithm/min.h>
#include <__assert>
#include <__config>
+#include <__cstddef/nullptr_t.h>
#include <__cstddef/ptrdiff_t.h>
#include <__cstddef/size_t.h>
#include <__functional/hash.h>
diff --git a/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.cmp/cmp_nullptr.pass.cpp b/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.cmp/cmp_nullptr.pass.cpp
index 4ca83dd..e0aea76 100644
--- a/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.cmp/cmp_nullptr.pass.cpp
+++ b/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.cmp/cmp_nullptr.pass.cpp
@@ -37,8 +37,9 @@
// template<class T>
// strong_ordering operator<=>(shared_ptr<T> const& x, nullptr_t) noexcept; // C++20
-#include <memory>
#include <cassert>
+#include <cstddef>
+#include <memory>
#include "test_macros.h"
#include "test_comparisons.h"
diff --git a/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp b/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
index 6f0ba2e..5ef9c4b 100644
--- a/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
+++ b/test/std/utilities/smartptr/unique.ptr/unique.ptr.special/cmp_nullptr.pass.cpp
@@ -39,9 +39,9 @@
// constexpr compare_three_way_result_t<typename unique_ptr<T, D>::pointer>
// operator<=>(const unique_ptr<T, D>& x, nullptr_t); // C++20
-#include <memory>
#include <cassert>
-#include <type_traits>
+#include <cstddef>
+#include <memory>
#include "test_macros.h"
#include "test_comparisons.h"
