[lib++][test] Align atomic_ref underlying variable as required (llvm#179780)

There is one pre-existing
`alignas(std::atomic_ref<T>::required_alignment)`:

https://github.com/llvm/llvm-project/blob/1f8a3f2fdbf51cbba4635ef05e8139039a105c2c/libcxx/test/std/atomics/atomics.ref/is_always_lock_free.pass.cpp#L54-L60
This PR adds more of them.

On 32-bit Windows ABI just creating a variable on stack is not enough,
so 32-bit MSVC fails these tests before the fix.

Author: AlexGuteniev

libcxx/test/std/atomics/atomics.ref/address.pass.cpp

@@ -20,7 +20,7 @@
 template <typename T>
 struct TestAddress {
   void operator()() const {
-    T x(T(1));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
     const std::atomic_ref<T> a(x);
 
     std::same_as<T*> decltype(auto) p = a.address();

libcxx/test/std/atomics/atomics.ref/assign.pass.cpp

@@ -24,7 +24,7 @@ template <typename T>
 struct TestAssign {
   void operator()() const {
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       std::same_as<T> decltype(auto) y = (a = T(2));

libcxx/test/std/atomics/atomics.ref/bitwise_and_assign.pass.cpp

@@ -32,7 +32,7 @@ struct TestBitwiseAndAssign {
   void operator()() const {
     static_assert(std::is_integral_v<T>);
 
-    T x(T(1));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
     std::atomic_ref<T> const a(x);
 
     std::same_as<T> decltype(auto) y = (a &= T(1));

libcxx/test/std/atomics/atomics.ref/bitwise_or_assign.pass.cpp

@@ -32,7 +32,7 @@ struct TestBitwiseOrAssign {
   void operator()() const {
     static_assert(std::is_integral_v<T>);
 
-    T x(T(1));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
     std::atomic_ref<T> const a(x);
 
     std::same_as<T> decltype(auto) y = (a |= T(2));

libcxx/test/std/atomics/atomics.ref/bitwise_xor_assign.pass.cpp

@@ -32,7 +32,7 @@ struct TestBitwiseXorAssign {
   void operator()() const {
     static_assert(std::is_integral_v<T>);
 
-    T x(T(1));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
     std::atomic_ref<T> const a(x);
 
     std::same_as<T> decltype(auto) y = (a ^= T(2));

libcxx/test/std/atomics/atomics.ref/compare_exchange_strong.pass.cpp

@@ -28,7 +28,7 @@ template <typename T>
 struct TestCompareExchangeStrong {
   void operator()() const {
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       T t(T(1));
@@ -44,7 +44,7 @@ struct TestCompareExchangeStrong {
       ASSERT_NOEXCEPT(a.compare_exchange_strong(t, T(2)));
     }
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       T t(T(1));
@@ -60,7 +60,7 @@ struct TestCompareExchangeStrong {
       ASSERT_NOEXCEPT(a.compare_exchange_strong(t, T(2), std::memory_order_seq_cst));
     }
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       T t(T(1));

libcxx/test/std/atomics/atomics.ref/compare_exchange_weak.pass.cpp

@@ -28,7 +28,7 @@ template <typename T>
 struct TestCompareExchangeWeak {
   void operator()() const {
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       T t(T(1));
@@ -44,7 +44,7 @@ struct TestCompareExchangeWeak {
       ASSERT_NOEXCEPT(a.compare_exchange_weak(t, T(2)));
     }
     {
-      T x(T(1));
+      alignas(std::atomic_ref<T>::required_alignment) T x(T(1));
       std::atomic_ref<T> const a(x);
 
       T t(T(1));

libcxx/test/std/atomics/atomics.ref/convert.pass.cpp

@@ -24,7 +24,7 @@ struct TestConvert {
   void operator()() const {
     T x(T(1));
 
-    T copy = x;
+    alignas(std::atomic_ref<T>::required_alignment) T copy = x;
     std::atomic_ref<T> const a(copy);
 
     T converted = a;

libcxx/test/std/atomics/atomics.ref/ctor.pass.cpp

@@ -25,7 +25,7 @@ struct TestCtor {
     static_assert(!std::is_convertible_v<T, std::atomic_ref<T>>);
     static_assert(std::is_constructible_v<std::atomic_ref<T>, T&>);
 
-    T x(T(0));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(0));
     std::atomic_ref<T> a(x);
     (void)a;
   }

libcxx/test/std/atomics/atomics.ref/deduction.pass.cpp

@@ -21,7 +21,7 @@
 template <typename T>
 struct TestDeduction {
   void operator()() const {
-    T x(T(0));
+    alignas(std::atomic_ref<T>::required_alignment) T x(T(0));
     std::atomic_ref a(x);
     ASSERT_SAME_TYPE(decltype(a), std::atomic_ref<T>);
   }