From af051f9be230f06eba587c25d56837fb48fcc9ee Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@qt.io>
Date: Wed, 14 Feb 2024 09:52:22 +0100
Subject: QVarLengthArray: re-publish Prealloc as a nested PreallocatedSize

This gives users of the class easy access to the Prealloc template
argument, without having to write a pattern-matcher like

   template <typename T>
   constexpr qsizetype preallocated_size_v;
   template <typename T, qsizetype N>
   constexpr qsizetype preallocated_size_v<QVarLengthArray<T,N>> = N;

first.

[ChangeLog][QtCore][QVarLengthArray] Added PreallocatedSize nested
constant, equal to the Prealloc template argument.

Change-Id: I928eaa5e62967445cdd7b0c2759567483fdb8997
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
---
 .../auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'tests/auto/corelib/tools')

diff --git a/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp b/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
index dcee8fd705..6a92663bc4 100644
--- a/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
+++ b/tests/auto/corelib/tools/qvarlengtharray/tst_qvarlengtharray.cpp
@@ -66,6 +66,7 @@ private slots:
     void sizeConstructor_QString() { sizeConstructor<QString>(); }
     void sizeConstructor_NonCopyable() { sizeConstructor<NonCopyable>(); }
     void append();
+    void preallocatedSize();
 #if QT_DEPRECATED_SINCE(6, 3)
     void prepend();
 #endif
@@ -194,6 +195,15 @@ void tst_QVarLengthArray::append()
     v2.append(5);
 }
 
+void tst_QVarLengthArray::preallocatedSize()
+{
+    // The default is 256:
+    static_assert(QVarLengthArray<int>::PreallocatedSize == 256);
+    // Otherwise, whatever was given as template argument:
+    static_assert(QVarLengthArray<int, 42>::PreallocatedSize == 42);
+    static_assert(QVarLengthArray<int, 1'000'000>::PreallocatedSize == 1'000'000);
+}
+
 #if QT_DEPRECATED_SINCE(6, 3)
 QT_WARNING_PUSH
 QT_WARNING_DISABLE_DEPRECATED
-- 
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