QRandomGenerator: port away from std::aligned_storage

It's deprecated in C++23. Just use an explicitly-aligned char array
directly, wrapped in a struct to avoid decays to char*.

Task-number: QTBUG-99122
Pick-to: 6.3 6.2
Change-Id: Ic5807f0161cd9f360baa07464988bc48b9679f64
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp
index daf0a46387..7ea983540e 100644
--- a/src/corelib/global/qrandom.cpp
+++ b/src/corelib/global/qrandom.cpp
@@ -353,16 +353,17 @@ struct QRandomGenerator::SystemAndGlobalGenerators
     //    the state in case another thread tries to lock the mutex. It's not
     //    a common scenario, but since sizeof(QRandomGenerator) >= 2560, the
     //    overhead is actually acceptable.
-    // 2) We use both alignas and std::aligned_storage<..., 64> because
-    //    some implementations of std::aligned_storage can't align to more
-    //    than a primitive type's alignment.
+    // 2) We use both alignas(T) and alignas(64) because some implementations
+    //    can't align to more than a primitive type's alignment.
     // 3) We don't store the entire system QRandomGenerator, only the space
     //    used by the QRandomGenerator::type member. This is fine because we
     //    (ab)use the common initial sequence exclusion to aliasing rules.
     QBasicMutex globalPRNGMutex;
     struct ShortenedSystem { uint type; } system_;
     SystemGenerator sys;
-    alignas(64) std::aligned_storage<sizeof(QRandomGenerator64), 64>::type global_;
+    alignas(64) struct {
+        alignas(QRandomGenerator64) uchar data[sizeof(QRandomGenerator64)];
+    } global_;
 
     constexpr SystemAndGlobalGenerators()
         : globalPRNGMutex{}, system_{0}, sys{}, global_{}