Move QSmallByteArray out of qcryptographichash.cpp

Its definition triggers QTCREATORBUG-28838, which has been marked as
Won't-Do.

By moving the class into its own header file, we limit the fallout of
said bug, which otherwise makes working in qcryptographichash.cpp a
nightmare with QtCreator.

Task-number: QTCREATORBUG-28838
Pick-to: 6.5
Change-Id: I12b8069ab77bfaee33b5df1b09757d617b142a44
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit d36835f0e3cb58a9858dc6cc13fbdec9ded7c227)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/corelib/CMakeLists.txt

@@ -304,6 +304,7 @@ qt_internal_add_module(Core
         tools/qsharedpointer.cpp tools/qsharedpointer.h
         tools/qsharedpointer_impl.h
         tools/qsize.cpp tools/qsize.h
+        tools/qsmallbytearray_p.h
         tools/qspan.h
         tools/qspan_p.h
         tools/qstack.h

src/corelib/tools/qcryptographichash.cpp

@@ -6,6 +6,7 @@
 #include <qcryptographichash.h>
 #include <qmessageauthenticationcode.h>
 
+#include <QtCore/private/qsmallbytearray_p.h>
 #include <qiodevice.h>
 #include <qmutex.h>
 #include <qvarlengtharray.h>
@@ -124,75 +125,6 @@ static inline int SHA384_512AddLength(SHA512Context *context, unsigned int lengt
 
 QT_BEGIN_NAMESPACE
 
-template <size_t N>
-class QSmallByteArray
-{
-    std::array<quint8, N> m_data;
-    static_assert(N <= (std::numeric_limits<std::uint8_t>::max)());
-    quint8 m_size = 0;
-public:
-    QSmallByteArray() = default;
-    // all compiler-generated SMFs are ok!
-    template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy ctor!
-    constexpr QSmallByteArray(const QSmallByteArray<M> &other) noexcept
-    {
-        assign(other);
-    }
-    template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy-assignment op!
-    constexpr QSmallByteArray &operator=(const QSmallByteArray<M> &other) noexcept
-    {
-        assign(other);
-        return *this;
-    }
-
-    template <typename Container> // ### underconstrained
-    constexpr void assign(const Container &c)
-    {
-        const size_t otherSize = size_t(std::size(c));
-        Q_ASSERT(otherSize < N);
-        memcpy(data(), std::data(c), otherSize);
-        m_size = quint8(otherSize);
-    }
-
-    constexpr quint8 *data() noexcept { return m_data.data(); }
-    constexpr const quint8 *data() const noexcept { return m_data.data(); }
-    constexpr qsizetype size() const noexcept { return qsizetype{m_size}; }
-    constexpr quint8 &operator[](qsizetype n)
-    {
-        Q_ASSERT(n < size());
-        return data()[n];
-    }
-    constexpr const quint8 &operator[](qsizetype n) const
-    {
-        Q_ASSERT(n < size());
-        return data()[n];
-    }
-    constexpr bool isEmpty() const noexcept { return size() == 0; }
-    constexpr void clear() noexcept { m_size = 0; }
-    constexpr void resizeForOverwrite(qsizetype s)
-    {
-        Q_ASSERT(s >= 0);
-        Q_ASSERT(size_t(s) <= N);
-        m_size = std::uint8_t(s);
-    }
-    constexpr void resize(qsizetype s, quint8 v)
-    {
-        const auto oldSize = size();
-        resizeForOverwrite(s);
-        if (s > oldSize)
-            memset(data() + oldSize, v, size() - oldSize);
-    }
-    constexpr QByteArrayView toByteArrayView() const noexcept
-    { return *this; }
-
-    constexpr auto begin() noexcept { return data(); }
-    constexpr auto begin() const noexcept { return data(); }
-    constexpr auto cbegin() const noexcept { return begin(); }
-    constexpr auto end() noexcept { return data() + size(); }
-    constexpr auto end() const noexcept { return data() + size(); }
-    constexpr auto cend() const noexcept { return end(); }
-};
-
 static constexpr int hashLengthInternal(QCryptographicHash::Algorithm method) noexcept
 {
     switch (method) {

src/corelib/tools/qsmallbytearray_p.h

@@ -0,0 +1,104 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+#ifndef QTCORE_QSMALLBYTEARRAY_P_H
+#define QTCORE_QSMALLBYTEARRAY_P_H
+
+#include <QtCore/qbytearrayview.h>
+#include <QtCore/qtconfigmacros.h>
+#include <QtCore/qtypes.h>
+
+#include <array>
+#include <limits>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+//
+// A fixed-max-size version of QByteArray. Since it's fixed-max-size, it's
+// never going to the heap. Can contain a maximum of 256 octets. Never
+// NUL-terminates on its own.
+//
+
+template <size_t N>
+class QSmallByteArray
+{
+    std::array<quint8, N> m_data;
+    static_assert(N <= (std::numeric_limits<std::uint8_t>::max)());
+    quint8 m_size = 0;
+public:
+    QSmallByteArray() = default;
+    // all compiler-generated SMFs are ok!
+    template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy ctor!
+    constexpr QSmallByteArray(const QSmallByteArray<M> &other) noexcept
+    {
+        assign(other);
+    }
+    template <std::size_t M, std::enable_if_t<M < N, bool> = true> // M == N is for copy-assignment op!
+    constexpr QSmallByteArray &operator=(const QSmallByteArray<M> &other) noexcept
+    {
+        assign(other);
+        return *this;
+    }
+
+    template <typename Container> // ### underconstrained
+    constexpr void assign(const Container &c)
+    {
+        const size_t otherSize = size_t(std::size(c));
+        Q_ASSERT(otherSize < N);
+        memcpy(data(), std::data(c), otherSize);
+        m_size = quint8(otherSize);
+    }
+
+    constexpr quint8 *data() noexcept { return m_data.data(); }
+    constexpr const quint8 *data() const noexcept { return m_data.data(); }
+    constexpr qsizetype size() const noexcept { return qsizetype{m_size}; }
+    constexpr quint8 &operator[](qsizetype n)
+    {
+        Q_ASSERT(n < size());
+        return data()[n];
+    }
+    constexpr const quint8 &operator[](qsizetype n) const
+    {
+        Q_ASSERT(n < size());
+        return data()[n];
+    }
+    constexpr bool isEmpty() const noexcept { return size() == 0; }
+    constexpr void clear() noexcept { m_size = 0; }
+    constexpr void resizeForOverwrite(qsizetype s)
+    {
+        Q_ASSERT(s >= 0);
+        Q_ASSERT(size_t(s) <= N);
+        m_size = std::uint8_t(s);
+    }
+    constexpr void resize(qsizetype s, quint8 v)
+    {
+        const auto oldSize = size();
+        resizeForOverwrite(s);
+        if (s > oldSize)
+            memset(data() + oldSize, v, size() - oldSize);
+    }
+    constexpr QByteArrayView toByteArrayView() const noexcept
+    { return *this; }
+
+    constexpr auto begin() noexcept { return data(); }
+    constexpr auto begin() const noexcept { return data(); }
+    constexpr auto cbegin() const noexcept { return begin(); }
+    constexpr auto end() noexcept { return data() + size(); }
+    constexpr auto end() const noexcept { return data() + size(); }
+    constexpr auto cend() const noexcept { return end(); }
+};
+
+QT_END_NAMESPACE
+
+#endif // QTCORE_QSMALLBYTEARRAY_P_H