QString et al: fix lastIndexOf() API asymmetry

Commit 6cee204d56205e250b0675c9c6d4dd8a2367f3c4 introduced overloads
of lastIndexOf() which drop the 'from' argument, inadvertently fixing
QTBUG-80694, but failed to provide the new overloads for all existing
lastIndexOf() overloads, making the fix for QTBUG-80694 incomplete.

This patch completes the fix, by adding the missing overloads (for
char-likes) and also adds the missing (non-regex) tests to
tst_qstringapisymmetry.

Also amends 1c164ec7f21a78025475c561a70b94d1e3dd6bb6.

Fixes: QTBUG-80694
Change-Id: Ib4b3d597d658ce2edf01a2bce0d711ecea593d6e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

5 files changed, 41 insertions, 4 deletions

diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index ca2ebe2b9e..a00383b304 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -4152,6 +4152,12 @@ qsizetype QString::lastIndexOf(QChar ch, qsizetype from, Qt::CaseSensitivity cs)
 }
 
 /*!
+  \fn QString::lastIndexOf(QChar ch, Qt::CaseSensitivity) const
+  \since 6.3
+  \overload lastIndexOf()
+*/
+
+/*!
   \fn qsizetype QString::lastIndexOf(QStringView str, qsizetype from, Qt::CaseSensitivity cs) const
   \since 5.14
   \overload lastIndexOf()
@@ -9313,6 +9319,7 @@ QString &QString::setRawData(const QChar *unicode, qsizetype size)
 */
 
 /*!
+    \fn qsizetype QLatin1String::lastIndexOf(QChar ch, Qt::CaseSensitivity cs) const
     \fn qsizetype QLatin1String::lastIndexOf(QLatin1Char ch, qsizetype from, Qt::CaseSensitivity cs) const
     \since 6.3
     \overload
diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h
index 5229c030e2..f53cb869c5 100644
--- a/src/corelib/text/qstring.h
+++ b/src/corelib/text/qstring.h
@@ -169,9 +169,13 @@ public:
     { return lastIndexOf(s, size(), cs); }
     [[nodiscard]] qsizetype lastIndexOf(QLatin1String s, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return QtPrivate::lastIndexOf(*this, from, s, cs); }
-    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    { return lastIndexOf(c, -1, cs); }
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return QtPrivate::lastIndexOf(*this, from, QStringView(&c, 1), cs); }
-    [[nodiscard]] qsizetype lastIndexOf(QLatin1Char c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    [[nodiscard]] qsizetype lastIndexOf(QLatin1Char c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    { return lastIndexOf(c, -1, cs); }
+    [[nodiscard]] qsizetype lastIndexOf(QLatin1Char c, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { char ch = c.toLatin1(); return QtPrivate::lastIndexOf(*this, from, QLatin1String(&ch, 1), cs); }
 
     using value_type = const char;
@@ -521,7 +525,9 @@ public:
 #endif
     [[nodiscard]] qsizetype indexOf(QStringView s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return QtPrivate::findString(*this, from, s, cs); }
-    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    { return lastIndexOf(c, -1, cs); }
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
     [[nodiscard]] qsizetype lastIndexOf(QLatin1String s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const
     { return lastIndexOf(s, size(), cs); }
     [[nodiscard]] qsizetype lastIndexOf(QLatin1String s, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const;
diff --git a/src/corelib/text/qstringview.cpp b/src/corelib/text/qstringview.cpp
index 79d0ccd819..faaed16044 100644
--- a/src/corelib/text/qstringview.cpp
+++ b/src/corelib/text/qstringview.cpp
@@ -915,6 +915,12 @@ QT_BEGIN_NAMESPACE
     \sa QString::lastIndexOf()
 */
 
+/*!
+    \fn QStringView::lastIndexOf(QChar c, Qt::CaseSensitivity cs) const
+    \since 6.3
+    \overload lastIndexOf()
+*/
+
 #if QT_CONFIG(regularexpression)
 /*!
     \fn qsizetype QStringView::indexOf(const QRegularExpression &re, qsizetype from, QRegularExpressionMatch *rmatch) const
diff --git a/src/corelib/text/qstringview.h b/src/corelib/text/qstringview.h
index 5c204fb7dd..5d05dd6edd 100644
--- a/src/corelib/text/qstringview.h
+++ b/src/corelib/text/qstringview.h
@@ -342,7 +342,9 @@ public:
     [[nodiscard]] qsizetype count(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return QtPrivate::count(*this, s, cs); }
 
-    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from = -1, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
+    { return lastIndexOf(c, -1, cs); }
+    [[nodiscard]] qsizetype lastIndexOf(QChar c, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return QtPrivate::lastIndexOf(*this, from, QStringView(&c, 1), cs); }
     [[nodiscard]] qsizetype lastIndexOf(QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive) const noexcept
     { return lastIndexOf(s, size(), cs); }
diff --git a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
index a64811cea4..c1795791c5 100644
--- a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
+++ b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
@@ -913,6 +913,15 @@ private Q_SLOTS:
     void isValidUtf8_QUtf8StringView() { isValidUtf8_impl<QUtf8StringView>(); }
 };
 
+namespace help {
+
+template <typename T> constexpr qsizetype size(const T &s) { return qsizetype(s.size()); }
+
+template <> constexpr qsizetype size(const QChar&) { return 1; }
+template <> constexpr qsizetype size(const QLatin1Char&) { return 1; }
+template <> constexpr qsizetype size(const char16_t&) { return 1; }
+} // namespace help
+
 namespace {
 
 void overload_s_a(const QString &) {}
@@ -2638,6 +2647,13 @@ void tst_QStringApiSymmetry::lastIndexOf_impl() const
     QCOMPARE(haystack.lastIndexOf(needle, startpos, Qt::CaseSensitive), size_type(resultCS));
     QCOMPARE(haystack.lastIndexOf(needle, startpos, Qt::CaseInsensitive), size_type(resultCIS));
 
+    if (startpos == haystack.size() ||
+        (startpos == -1 && help::size(needle) > 0)) { // -1 skips past-the-end-match w/empty needle
+        // check that calls without an explicit 'from' argument work, too:
+        QCOMPARE(haystack.lastIndexOf(needle), size_type(resultCS));
+        QCOMPARE(haystack.lastIndexOf(needle, Qt::CaseSensitive), size_type(resultCS));
+        QCOMPARE(haystack.lastIndexOf(needle, Qt::CaseInsensitive), size_type(resultCIS));
+    }
 }
 
 void tst_QStringApiSymmetry::indexOf_contains_lastIndexOf_count_regexp_data()