QVarLengthArray: Move unique_ptr<void, free_deleter> to QVLABaseBase

This avoids repeated re-instantiations of unique_ptr with local
deleters, removing that instantiation from the top of the list in
Clang -ftime-trace QtWidgets builds:

**** Templates that took longest to instantiate:
  2627 ms: std::__1::unique_ptr<void, free_deleter> (835 times, avg 3 ms)

Amends e297e80fd0ec6ce4c97ee1b40426c76377b45ecc.

Pick-to: 6.3
Task-number: QTBUG-97601
Task-number: QTBUG-99039
Change-Id: I1281f6cf9248a3796d9dfdc653f19f5a67dc3bda
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index 5898e486f9..261cdcb5cd 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -96,6 +96,11 @@ protected:
         Q_ASSERT(n <= size() - pos);
     }
 
+    struct free_deleter {
+        void operator()(void *p) const noexcept { free(p); }
+    };
+    using malloced_ptr = std::unique_ptr<void, free_deleter>;
+
 public:
     using size_type = qsizetype;
 
@@ -748,10 +753,7 @@ Q_OUTOFLINE_TEMPLATE void QVLABase<T>::reallocate_impl(qsizetype prealloc, void
     Q_ASSUME(copySize >= 0);
 
     if (aalloc != capacity()) {
-        struct free_deleter {
-            void operator()(void *p) const noexcept { free(p); }
-        };
-        std::unique_ptr<void, free_deleter> guard;
+        QVLABaseBase::malloced_ptr guard;
         void *newPtr;
         qsizetype newA;
         if (aalloc > prealloc) {