Containers: add max_size()

One more method for STL compatibility.
This one is particularly subtle as it's required by the
`reservable-container` concept:

https://eel.is/c++draft/ranges#range.utility.conv.general-3

Without this concept, ranges::to won't reserve() before copying the
elements (out of a sized range which isn't a common_range).

Implementation notes: there were already a couple of constants denoting
the maximum QByteArray and QString size. Centralize that implementation
in QTypedArrayData, so that QList can use it too.

The maximum allocation size (private constant) needs a even more central
place so that even QVLA can use it. Lacking anything better, I've put it
in qcontainerfwd.h.

Since our containers aren't allocator-aware, I can make max_size() a
static member, and replace the existing constants throughout the rest of
qtbase. (I can't kill them yet as they're used by other submodules.)

[ChangeLog][QtCore][QList] Added max_size().

[ChangeLog][QtCore][QString] Added max_size().

[ChangeLog][QtCore][QByteArray] Added max_size().

[ChangeLog][QtCore][QVarLengthArray] Added max_size().

Change-Id: I176142e31b998f4f787c96333894b8f6653eb70d
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/src/corelib/serialization/qcborvalue.cpp b/src/corelib/serialization/qcborvalue.cpp
index 4fb7618017..57fdae322e 100644
--- a/src/corelib/serialization/qcborvalue.cpp
+++ b/src/corelib/serialization/qcborvalue.cpp
@@ -19,7 +19,6 @@
 #include <qlocale.h>
 #include <qdatetime.h>
 #include <qtimezone.h>
-#include <private/qbytearray_p.h>
 #include <private/qnumeric_p.h>
 #include <private/qsimd_p.h>
 
@@ -1616,7 +1615,7 @@ void QCborContainerPrivate::decodeStringFromCbor(QCborStreamReader &reader)
         // add space for aligned ByteData (this can't overflow)
         offset += sizeof(QtCbor::ByteData) + alignof(QtCbor::ByteData);
         offset &= ~(alignof(QtCbor::ByteData) - 1);
-        if (offset > size_t(MaxByteArraySize)) {
+        if (offset > size_t(QByteArray::max_size())) {
             // overflow
             setErrorInReader(reader, { QCborError::DataTooLarge });
             return;
@@ -1629,9 +1628,9 @@ void QCborContainerPrivate::decodeStringFromCbor(QCborStreamReader &reader)
             // so capa how much we allocate
             newCapacity = offset + MaxMemoryIncrement - EstimatedOverhead;
         }
-        if (newCapacity > size_t(MaxByteArraySize)) {
+        if (newCapacity > size_t(QByteArray::max_size())) {
             // this may cause an allocation failure
-            newCapacity = MaxByteArraySize;
+            newCapacity = QByteArray::max_size();
         }
         if (newCapacity > size_t(data.capacity()))
             data.reserve(newCapacity);
@@ -1682,7 +1681,7 @@ void QCborContainerPrivate::decodeStringFromCbor(QCborStreamReader &reader)
 
         // check that this UTF-8 text string can be loaded onto a QString
         if (e.type == QCborValue::String) {
-            if (Q_UNLIKELY(b->len > MaxStringSize)) {
+            if (Q_UNLIKELY(b->len > QString::max_size())) {
                 setErrorInReader(reader, { QCborError::DataTooLarge });
                 status = QCborStreamReader::Error;
             }