[libc++] std::atomic primary template should not have a difference_type member type (llvm#123236)

The test would not check its absence and the code path intended for
pointer was never actually instantiated.
I added a few pointer types since there was no coverage.

---------

Co-authored-by: Louis Dionne <[email protected]>

Author: dalg24

libcxx/include/__atomic/atomic.h

@@ -40,6 +40,8 @@ struct __atomic_base // false
 {
   mutable __cxx_atomic_impl<_Tp> __a_;
 
+  using value_type = _Tp;
+
 #if _LIBCPP_STD_VER >= 17
   static constexpr bool is_always_lock_free = __libcpp_is_always_lock_free<__cxx_atomic_impl<_Tp> >::__value;
 #endif
@@ -145,6 +147,8 @@ template <class _Tp>
 struct __atomic_base<_Tp, true> : public __atomic_base<_Tp, false> {
   using __base _LIBCPP_NODEBUG = __atomic_base<_Tp, false>;
 
+  using difference_type = typename __base::value_type;
+
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __atomic_base() _NOEXCEPT = default;
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __base(__d) {}
@@ -229,8 +233,6 @@ struct __atomic_waitable_traits<__atomic_base<_Tp, _IsIntegral> > {
 template <class _Tp>
 struct atomic : public __atomic_base<_Tp> {
   using __base _LIBCPP_NODEBUG = __atomic_base<_Tp>;
-  using value_type             = _Tp;
-  using difference_type        = value_type;
 
 #if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI atomic() = default;
@@ -258,8 +260,8 @@ struct atomic : public __atomic_base<_Tp> {
 template <class _Tp>
 struct atomic<_Tp*> : public __atomic_base<_Tp*> {
   using __base _LIBCPP_NODEBUG = __atomic_base<_Tp*>;
-  using value_type             = _Tp*;
-  using difference_type        = ptrdiff_t;
+
+  using difference_type = ptrdiff_t;
 
   _LIBCPP_HIDE_FROM_ABI atomic() _NOEXCEPT = default;
 

libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add.verify.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 // <atomic>
 
 // template <class T>
@@ -63,12 +65,12 @@ struct S {
 void member_function_pointer() {
   {
     volatile std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_add' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_add'}}
     std::atomic_fetch_add(&fun, 0);
   }
   {
     std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_add' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_add'}}
     std::atomic_fetch_add(&fun, 0);
   }
 }

libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_add_explicit.verify.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 // <atomic>
 
 // template <class T>
@@ -66,12 +68,12 @@ struct S {
 void member_function_pointer() {
   {
     volatile std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_add' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_add_explicit'}}
     std::atomic_fetch_add_explicit(&fun, 0, std::memory_order_relaxed);
   }
   {
     std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_add' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_add_explicit'}}
     std::atomic_fetch_add_explicit(&fun, 0, std::memory_order_relaxed);
   }
 }

libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub.verify.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 // <atomic>
 
 // template <class T>
@@ -63,12 +65,12 @@ struct S {
 void member_function_pointer() {
   {
     volatile std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_sub' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_sub'}}
     std::atomic_fetch_sub(&fun, 0);
   }
   {
     std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_sub' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_sub'}}
     std::atomic_fetch_sub(&fun, 0);
   }
 }

libcxx/test/libcxx/atomics/atomics.types.operations/atomics.types.operations.req/atomic_fetch_sub_explicit.verify.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 // <atomic>
 
 // template <class T>
@@ -66,12 +68,12 @@ struct S {
 void member_function_pointer() {
   {
     volatile std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_sub' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_sub_explicit'}}
     std::atomic_fetch_sub_explicit(&fun, 0, std::memory_order_relaxed);
   }
   {
     std::atomic<void (S::*)(int)> fun;
-    // expected-error@*:* {{no member named 'fetch_sub' in}}
+    // expected-error@*:* {{no matching function for call to 'atomic_fetch_sub_explicit'}}
     std::atomic_fetch_sub_explicit(&fun, 0, std::memory_order_relaxed);
   }
 }