QVersionNumber: port fromString() to QAnyStringView

We can handle the UTF-8 case by reinterpreting it as Latin-1.

This way, the suffixIndex stays valid as a return value.

As a drive-by, optimize away toLatin1() calls by using a QVLA.
We really need a better way of converting UTF-16 -> L1 than
qt_to_latin1()...

[ChangeLog][QtCore][QVersionNumber] fromString() now takes
QAnyStringView (was: QString, QStringView, QLatin1String)
and a qsizetype pointer (was: int pointer).

Change-Id: I86abaadba2792658fbf93ccd1e0b86e3302c697c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

5 files changed, 60 insertions, 68 deletions

diff --git a/src/corelib/compat/removed_api.cpp b/src/corelib/compat/removed_api.cpp
index 61d3842e64..5f59cf047a 100644
--- a/src/corelib/compat/removed_api.cpp
+++ b/src/corelib/compat/removed_api.cpp
@@ -114,38 +114,30 @@ QByteArray QtPrivate::QByteArrayList_join(const QByteArrayList *that, const char
 }
 
 #endif // QT_REMOVED_SINCE(6, 3)
+
 #if QT_REMOVED_SINCE(6, 4)
 
 #include "qversionnumber.h"
 
-#  if QT_POINTER_SIZE != 4
+QT_WARNING_PUSH
+QT_WARNING_DISABLE_DEPRECATED
+
 QVersionNumber QVersionNumber::fromString(const QString &string, int *suffixIndex)
 {
-    qsizetype si;
-    QVersionNumber r = fromString(QLatin1String(string.toLatin1()), &si);
-    if (suffixIndex)
-        *suffixIndex = si;
-    return r;
+    return fromString(qToAnyStringViewIgnoringNull(string), suffixIndex);
 }
 
 QVersionNumber QVersionNumber::fromString(QStringView string, int *suffixIndex)
 {
-    qsizetype si;
-    QVersionNumber r = fromString(QLatin1String(string.toLatin1()), &si);
-    if (suffixIndex)
-        *suffixIndex = si;
-    return r;
+    return fromString(QAnyStringView{string}, suffixIndex);
 }
 
 QVersionNumber QVersionNumber::fromString(QLatin1String string, int *suffixIndex)
 {
-    qsizetype si;
-    QVersionNumber r = fromString(string, &si);
-    if (suffixIndex)
-        *suffixIndex = si;
-    return r;
+    return fromString(QAnyStringView{string}, suffixIndex);
 }
-#  endif // QT_POINTER_SIZE != 4
+
+QT_WARNING_POP
 
 // #include <qotherheader.h>
 // // implement removed functions from qotherheader.h
diff --git a/src/corelib/doc/snippets/qversionnumber/main.cpp b/src/corelib/doc/snippets/qversionnumber/main.cpp
index 27b7b1a7ef..1a520a1cef 100644
--- a/src/corelib/doc/snippets/qversionnumber/main.cpp
+++ b/src/corelib/doc/snippets/qversionnumber/main.cpp
@@ -90,7 +90,7 @@ void QObject::parse()
 {
     //! [3]
     QString string("5.4.0-alpha");
-    int suffixIndex;
+    qsizetype suffixIndex;
     QVersionNumber version = QVersionNumber::fromString(string, &suffixIndex);
     // version is 5.4.0
     // suffixIndex is 5
@@ -98,7 +98,7 @@ void QObject::parse()
 
     //! [3-latin1-1]
     QLatin1String string("5.4.0-alpha");
-    int suffixIndex;
+    qsizetype suffixIndex;
     auto version = QVersionNumber::fromString(string, &suffixIndex);
     // version is 5.4.0
     // suffixIndex is 5
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 9742f5ad83..23927b0e84 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -995,7 +995,7 @@ static void qt_to_latin1_internal(uchar *dst, const char16_t *src, qsizetype len
 #endif
 }
 
-static void qt_to_latin1(uchar *dst, const char16_t *src, qsizetype length)
+void qt_to_latin1(uchar *dst, const char16_t *src, qsizetype length)
 {
     qt_to_latin1_internal<true>(dst, src, length);
 }
diff --git a/src/corelib/tools/qversionnumber.cpp b/src/corelib/tools/qversionnumber.cpp
index d30608534f..4aa8cdd346 100644
--- a/src/corelib/tools/qversionnumber.cpp
+++ b/src/corelib/tools/qversionnumber.cpp
@@ -400,48 +400,9 @@ QString QVersionNumber::toString() const
     return version;
 }
 
-#if QT_STRINGVIEW_LEVEL < 2
 /*!
-    Constructs a QVersionNumber from a specially formatted \a string of
-    non-negative decimal numbers delimited by a period (\c{.}).
-
-    Once the numerical segments have been parsed, the remainder of the string
-    is considered to be the suffix string.  The start index of that string will be
-    stored in \a suffixIndex if it is not null.
-
-    \snippet qversionnumber/main.cpp 3
-
-    \sa isNull()
-*/
-QVersionNumber QVersionNumber::fromString(const QString &string, qsizetype *suffixIndex)
-{
-    return fromString(QLatin1String(string.toLatin1()), suffixIndex);
-}
-#endif
-
-/*!
-    \since 5.10
-    \overload
-
-    Constructs a QVersionNumber from a specially formatted \a string of
-    non-negative decimal numbers delimited by '.'.
-
-    Once the numerical segments have been parsed, the remainder of the string
-    is considered to be the suffix string.  The start index of that string will be
-    stored in \a suffixIndex if it is not null.
-
-    \snippet qversionnumber/main.cpp 3
-
-    \sa isNull()
-*/
-QVersionNumber QVersionNumber::fromString(QStringView string, qsizetype *suffixIndex)
-{
-    return fromString(QLatin1String(string.toLatin1()), suffixIndex);
-}
-
-/*!
-    \since 5.10
-    \overload
+    \fn QVersionNumber QVersionNumber::fromString(QAnyStringView string, qsizetype *suffixIndex)
+    \since 6.4
 
     Constructs a QVersionNumber from a specially formatted \a string of
     non-negative decimal numbers delimited by '.'.
@@ -452,9 +413,13 @@ QVersionNumber QVersionNumber::fromString(QStringView string, qsizetype *suffixI
 
     \snippet qversionnumber/main.cpp 3-latin1-1
 
+    \note In versions prior to Qt 6.4, this function was overloaded for QString,
+    QLatin1String and QStringView instead, and \a suffixIndex was an \c{int*}.
+
     \sa isNull()
 */
-QVersionNumber QVersionNumber::fromString(QLatin1String string, qsizetype *suffixIndex)
+
+static QVersionNumber from_string(QLatin1String string, qsizetype *suffixIndex)
 {
     QList<int> seg;
 
@@ -479,6 +444,27 @@ QVersionNumber QVersionNumber::fromString(QLatin1String string, qsizetype *suffi
     return QVersionNumber(std::move(seg));
 }
 
+static QVersionNumber from_string(q_no_char8_t::QUtf8StringView string, qsizetype *suffixIndex)
+{
+    return from_string(QLatin1String(string.data(), string.size()), suffixIndex);
+}
+
+// in qstring.cpp
+extern void qt_to_latin1(uchar *dst, const char16_t *uc, qsizetype len);
+
+static QVersionNumber from_string(QStringView string, qsizetype *suffixIndex)
+{
+    QVarLengthArray<char> copy;
+    copy.resize(string.size());
+    qt_to_latin1(reinterpret_cast<uchar*>(copy.data()), string.utf16(), string.size());
+    return from_string(QLatin1String(copy.data(), copy.size()), suffixIndex);
+}
+
+QVersionNumber QVersionNumber::fromString(QAnyStringView string, qsizetype *suffixIndex)
+{
+    return string.visit([=] (auto string) { return from_string(string, suffixIndex); });
+}
+
 void QVersionNumber::SegmentStorage::setVector(int len, int maj, int min, int mic)
 {
     pointer_segments = new QList<int>;
diff --git a/src/corelib/tools/qversionnumber.h b/src/corelib/tools/qversionnumber.h
index 175abe4e61..ad8367c135 100644
--- a/src/corelib/tools/qversionnumber.h
+++ b/src/corelib/tools/qversionnumber.h
@@ -275,13 +275,28 @@ public:
     [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber commonPrefix(const QVersionNumber &v1, const QVersionNumber &v2);
 
     [[nodiscard]] Q_CORE_EXPORT QString toString() const;
-#if QT_STRINGVIEW_LEVEL < 2
-    [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(const QString &string, qsizetype *suffixIndex = nullptr);
+    [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(QAnyStringView string, qsizetype *suffixIndex = nullptr);
+
+#if QT_DEPRECATED_SINCE(6, 4) && QT_POINTER_SIZE != 4
+    Q_WEAK_OVERLOAD
+    QT_DEPRECATED_VERSION_X_6_4("Use the 'qsizetype *suffixIndex' overload.")
+    [[nodiscard]] static QVersionNumber fromString(QAnyStringView string, int *suffixIndex)
+    {
+        QT_WARNING_PUSH
+        // fromString() writes to *n unconditionally, but GCC can't know that
+        QT_WARNING_DISABLE_GCC("-Wmaybe-uninitialized")
+        qsizetype n;
+        auto r = fromString(string, &n);
+        if (suffixIndex) {
+            Q_ASSERT(int(n) == n);
+            *suffixIndex = int(n);
+        }
+        return r;
+        QT_WARNING_POP
+    }
 #endif
-    [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(QLatin1String string, qsizetype *suffixIndex = nullptr);
-    [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(QStringView string, qsizetype *suffixIndex = nullptr);
 
-#if QT_REMOVED_SINCE(6, 4) && QT_POINTER_SIZE != 4
+#if QT_REMOVED_SINCE(6, 4)
     [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(const QString &string, int *suffixIndex);
     [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(QLatin1String string, int *suffixIndex);
     [[nodiscard]] Q_CORE_EXPORT static Q_DECL_PURE_FUNCTION QVersionNumber fromString(QStringView string, int *suffixIndex);
@@ -305,7 +320,6 @@ public:
     [[nodiscard]] friend bool operator!=(const QVersionNumber &lhs, const QVersionNumber &rhs) noexcept
     { return compare(lhs, rhs) != 0; }
 
-
 private:
 #ifndef QT_NO_DATASTREAM
     friend Q_CORE_EXPORT QDataStream& operator>>(QDataStream &in, QVersionNumber &version);