4 files changed, 8 insertions, 5 deletions
diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 5a61d7f70d..94d22e288e 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -334,7 +334,7 @@ int qstricmp(const char *str1, const char *str2)
         return int(Incomplete);
     };
 
-#if defined(__SSE4_1__) && !(defined(__SANITIZE_ADDRESS__) || QT_HAS_FEATURE(address_sanitizer))
+#if defined(__SSE4_1__) && !(defined(__SANITIZE_ADDRESS__) || __has_feature(address_sanitizer))
     enum { PageSize = 4096, PageMask = PageSize - 1 };
     const __m128i zero = _mm_setzero_si128();
     forever {
diff --git a/src/corelib/text/qbytearray.h b/src/corelib/text/qbytearray.h
index 4fa17cf58b..36cf580cd9 100644
--- a/src/corelib/text/qbytearray.h
+++ b/src/corelib/text/qbytearray.h
@@ -264,7 +264,7 @@ public:
     void chop(int n);
 
 #if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP) && !defined(Q_CLANG_QDOC)
-#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !__has_cpp_attribute(nodiscard)
     // required due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61941
 #    pragma push_macro("Q_REQUIRED_RESULT")
 #    undef Q_REQUIRED_RESULT
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 51aa0b7512..4d83f19db7 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -146,6 +146,9 @@ qsizetype qFindStringBoyerMoore(QStringView haystack, qsizetype from, QStringVie
 static inline qsizetype qFindChar(QStringView str, QChar ch, qsizetype from, Qt::CaseSensitivity cs) noexcept;
 template <typename Haystack>
 static inline qsizetype qLastIndexOf(Haystack haystack, QChar needle, qsizetype from, Qt::CaseSensitivity cs) noexcept;
+template <>
+inline qsizetype qLastIndexOf(QString haystack, QChar needle,
+                              qsizetype from, Qt::CaseSensitivity cs) noexcept = delete; // unwanted, would detach
 static inline qsizetype qt_string_count(QStringView haystack, QStringView needle, Qt::CaseSensitivity cs);
 static inline qsizetype qt_string_count(QStringView haystack, QChar needle, Qt::CaseSensitivity cs);
 
@@ -3817,7 +3820,7 @@ int QString::indexOf(const QStringRef &str, int from, Qt::CaseSensitivity cs) co
 int QString::lastIndexOf(const QString &str, int from, Qt::CaseSensitivity cs) const
 {
     // ### Qt6: qsizetype
-    return int(QtPrivate::lastIndexOf(*this, from, str, cs));
+    return int(QtPrivate::lastIndexOf(QStringView(*this), from, str, cs));
 }
 
 #endif // QT_STRINGVIEW_LEVEL < 2
@@ -3856,7 +3859,7 @@ int QString::lastIndexOf(QLatin1String str, int from, Qt::CaseSensitivity cs) co
 int QString::lastIndexOf(QChar ch, int from, Qt::CaseSensitivity cs) const
 {
     // ### Qt6: qsizetype
-    return int(qLastIndexOf(*this, ch, from, cs));
+    return int(qLastIndexOf(QStringView(*this), ch, from, cs));
 }
 
 #if QT_STRINGVIEW_LEVEL < 2
diff --git a/src/corelib/text/qstring.h b/src/corelib/text/qstring.h
index 5def2c81a1..1669d7c94a 100644
--- a/src/corelib/text/qstring.h
+++ b/src/corelib/text/qstring.h
@@ -487,7 +487,7 @@ public:
     Q_REQUIRED_RESULT QString rightJustified(int width, QChar fill = QLatin1Char(' '), bool trunc = false) const;
 
 #if defined(Q_COMPILER_REF_QUALIFIERS) && !defined(QT_COMPILING_QSTRING_COMPAT_CPP) && !defined(Q_CLANG_QDOC)
-#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !QT_HAS_CPP_ATTRIBUTE(nodiscard)
+#  if defined(Q_CC_GNU) && !defined(Q_CC_CLANG) && !defined(Q_CC_INTEL) && !__has_cpp_attribute(nodiscard)
     // required due to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61941
 #    pragma push_macro("Q_REQUIRED_RESULT")
 #    undef Q_REQUIRED_RESULT