From c581474dfbfcb517573d8870cbbdc53f579e09cc Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Fri, 10 Feb 2023 14:25:20 +0100
Subject: [PATCH] QVarLengthArray: clear() is not resize(0)
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The latter needs the value_type to be default-constructible, which
shouldn't be required to clear() a container.

Use std::destroy_n() instead.

[ChangeLog][QtCore][QVarLengthArray] clear() no longer requires the
value_type to be default-constructible.

Manual conflict resolutions:
 - No QVLAStorage/Base/QVarLengthArray split in 6.2, yet

Change-Id: I806de8f3826b50c0bd38156892c3afeb15f13ac9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit fbfee2d7c59a7c6cd17ae7a3f63f983b9f3316f5)
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
---
 src/corelib/tools/qvarlengtharray.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index 50b80d9f54e..67d8bdcdd16 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -183,7 +183,12 @@ public:
     }
     inline bool isEmpty() const { return (s == 0); }
     inline void resize(qsizetype size);
-    inline void clear() { resize(0); }
+    void clear()
+    {
+        if constexpr (QTypeInfo<T>::isComplex)
+            std::destroy_n(data(), size());
+        s = 0;
+    }
     inline void squeeze();
 
     inline qsizetype capacity() const { return a; }