5 files changed, 32 insertions, 5 deletions
diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 3df77f179c..8e34ab0742 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -14,7 +14,6 @@
 #include "private/qsimd_p.h"
 #include "qstringalgorithms_p.h"
 #include "qscopedpointer.h"
-#include "qbytearray_p.h"
 #include "qstringconverter_p.h"
 #include <qdatastream.h>
 #include <qmath.h>
@@ -780,7 +779,7 @@ QByteArray qUncompress(const uchar* data, qsizetype nbytes)
         return QByteArray();
     }
 
-    constexpr auto MaxDecompressedSize = size_t(MaxByteArraySize);
+    constexpr auto MaxDecompressedSize = size_t(QByteArray::max_size());
     if constexpr (MaxDecompressedSize < std::numeric_limits<CompressSizeHint_t>::max()) {
         if (expectedSize > MaxDecompressedSize)
             return tooMuchData(ZLibOp::Decompression);
@@ -1389,6 +1388,15 @@ QByteArray &QByteArray::operator=(const char *str)
     \sa isEmpty(), resize()
 */
 
+/*! \fn qsizetype QByteArray::max_size()
+    \since 6.8
+
+    This function is provided for STL compatibility.
+    It returns the maximum number of elements that the byte array can
+    theoretically hold. In practice, the number can be much smaller,
+    limited by the amount of memory available to the system.
+*/
+
 /*! \fn bool QByteArray::isEmpty() const
 
     Returns \c true if the byte array has size 0; otherwise returns \c false.
diff --git a/src/corelib/text/qbytearray.h b/src/corelib/text/qbytearray.h
index a673383438..248bcc0b7b 100644
--- a/src/corelib/text/qbytearray.h
+++ b/src/corelib/text/qbytearray.h
@@ -519,6 +519,11 @@ public:
     void shrink_to_fit() { squeeze(); }
     iterator erase(const_iterator first, const_iterator last);
     inline iterator erase(const_iterator it) { return erase(it, it + 1); }
+    static constexpr qsizetype max_size() noexcept
+    {
+        // -1 to deal with the NUL terminator
+        return Data::max_size() - 1;
+    }
 
     static QByteArray fromStdString(const std::string &s);
     std::string toStdString() const;
diff --git a/src/corelib/text/qbytearray_p.h b/src/corelib/text/qbytearray_p.h
index 8fc3d7e357..7103a0428a 100644
--- a/src/corelib/text/qbytearray_p.h
+++ b/src/corelib/text/qbytearray_p.h
@@ -16,13 +16,12 @@
 //
 
 #include <QtCore/qbytearray.h>
-#include "private/qtools_p.h"
 
 QT_BEGIN_NAMESPACE
 
 // -1 because of the terminating NUL
-constexpr qsizetype MaxByteArraySize = MaxAllocSize - sizeof(std::remove_pointer<QByteArray::DataPointer>::type) - 1;
-constexpr qsizetype MaxStringSize = (MaxAllocSize - sizeof(std::remove_pointer<QByteArray::DataPointer>::type)) / 2 - 1;
+constexpr qsizetype MaxByteArraySize = QtPrivate::MaxAllocSize - sizeof(std::remove_pointer<QByteArray::DataPointer>::type) - 1;
+constexpr qsizetype MaxStringSize = (QtPrivate::MaxAllocSize - sizeof(std::remove_pointer<QByteArray::DataPointer>::type)) / 2 - 1;
 
 QT_END_NAMESPACE
 
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index d3bb1d92d1..f8fab76d73 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -6261,6 +6261,16 @@ QString& QString::fill(QChar ch, qsizetype size)
     \sa isEmpty(), resize()
 */
 
+/*!
+    \fn qsizetype QString::max_size()
+    \since 6.8
+
+    This function is provided for STL compatibility.
+    It returns the maximum number of elements that the string can
+    theoretically hold. In practice, the number can be much smaller,
+    limited by the amount of memory available to the system.
+*/
+
 /*! \fn bool QString::isNull() const
 
     Returns \c true if this string is null; otherwise returns \c false.
diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h
index 780b3090c1..5936f76ed4 100644
--- a/src/corelib/text/qstring.h
+++ b/src/corelib/text/qstring.h
@@ -941,6 +941,11 @@ public:
     void shrink_to_fit() { squeeze(); }
     iterator erase(const_iterator first, const_iterator last);
     inline iterator erase(const_iterator it) { return erase(it, it + 1); }
+    static constexpr qsizetype max_size() noexcept
+    {
+        // -1 to deal with the NUL terminator
+        return Data::max_size() - 1;
+    }
 
     static inline QString fromStdString(const std::string &s);
     inline std::string toStdString() const;