diff --git a/i18npool/source/localedata/LocaleNode.cxx b/i18npool/source/localedata/LocaleNode.cxx
index b0d9156ddbb9..e5123969644c 100644
--- a/i18npool/source/localedata/LocaleNode.cxx
+++ b/i18npool/source/localedata/LocaleNode.cxx
@@ -794,7 +794,7 @@ void LCFormatNode::generateCode (const OFileWriter &of) const
                         if (n100s < 0)
                             incErrorInt( "Error: Time100SecSeparator not present in FormatCode formatindex=\"%d\".\n",
                                     formatindex);
-                        n100s = aCode.indexOf( pSep->getValue() + "00");
+                        n100s = aCode.indexOf( OUString(pSep->getValue() + "00"));
                         if (n100s < 0)
                             incErrorInt( "Error: Time100SecSeparator+00 not present in FormatCode formatindex=\"%d\".\n",
                                     formatindex);
diff --git a/include/rtl/stringutils.hxx b/include/rtl/stringutils.hxx
index 29a7904e6019..2a6f841ecaed 100644
--- a/include/rtl/stringutils.hxx
+++ b/include/rtl/stringutils.hxx
@@ -94,6 +94,7 @@ struct SAL_WARN_UNUSED OUStringChar_ {
     constexpr OUStringChar_(sal_Unicode theC): c(theC) {}
     constexpr OUStringChar_(char theC): c(theC) { assert(c <= 0x7F); }
     template<typename T> OUStringChar_(T &&) = delete;
+    constexpr operator std::u16string_view() const { return {&c, 1}; }
     sal_Unicode const c;
 };
 using OUStringChar = OUStringChar_ const;
diff --git a/include/rtl/ustring.h b/include/rtl/ustring.h
index 5e481c21c4c4..6bf0d2aef0eb 100644
--- a/include/rtl/ustring.h
+++ b/include/rtl/ustring.h
@@ -2001,6 +2001,41 @@ SAL_DLLPUBLIC void SAL_CALL rtl_uString_newReplaceAllUtf16LUtf16L(
     sal_Int32 fromLength, sal_Unicode const * to, sal_Int32 toLength)
     SAL_THROW_EXTERN_C();
 
+#if defined LIBO_INTERNAL_ONLY
+/** Create a new string by replacing all occurrences of a given substring with
+    another substring.
+
+    Replacing subsequent occurrences picks up only after a given replacement.
+    That is, replacing from "xa" to "xx" in "xaa" results in "xxa", not "xxx".
+
+    @param[in, out] newStr  pointer to the new string; must not be null; must
+    point to null or a valid rtl_uString; upon return, points to the newly
+    allocated string or to null if there was either an out-of-memory condition
+    or the resulting number of UTF-16 code units would have been larger than
+    SAL_MAX_INT32
+
+    @param str  pointer to the original string; must not be null
+
+    @param from  pointer to the substring to be replaced; must not be null and
+    must point to memory of at least \p fromLength UTF-16 code units
+
+    @param fromLength  the length of the \p from substring; must be non-negative
+
+    @param to  pointer to the substring to be replaced; must not be null and
+    must point to memory of at least \p toLength UTF-16 code units
+
+    @param toLength  the length of the \p to substring; must be non-negative
+
+    @param fromIndex  the position in the string where we will begin searching
+
+    @since LibreOffice 7.1
+*/
+SAL_DLLPUBLIC void SAL_CALL rtl_uString_newReplaceAllFromIndexUtf16LUtf16L(
+    rtl_uString ** newStr, rtl_uString * str, sal_Unicode const * from,
+    sal_Int32 fromLength, sal_Unicode const * to, sal_Int32 toLengt, sal_Int32 fromIndex)
+    SAL_THROW_EXTERN_C();
+#endif
+
 /** Create a new string by converting all ASCII uppercase letters to lowercase
     within another string.
 
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 8e7a61f79005..d53eab6c3038 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -789,11 +789,18 @@ public:
                 < 0 - if this string is less than the string argument
                 > 0 - if this string is greater than the string argument
     */
+#if defined LIBO_INTERNAL_ONLY
+    sal_Int32 reverseCompareTo(std::u16string_view sv) const {
+        return rtl_ustr_reverseCompare_WithLength(
+            pData->buffer, pData->length, sv.data(), sv.size());
+    }
+#else
     sal_Int32 reverseCompareTo( const OUString & str ) const
     {
         return rtl_ustr_reverseCompare_WithLength( pData->buffer, pData->length,
                                                    str.pData->buffer, str.pData->length );
     }
+#endif
 
     /**
      @overload
@@ -811,25 +818,6 @@ public:
             libreoffice_internal::ConstCharArrayDetector<T>::length);
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, sal_Int32>::TypeUtf16
-    reverseCompareTo(T & literal) const {
-        return rtl_ustr_reverseCompare_WithLength(
-            pData->buffer, pData->length,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(literal),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    sal_Int32 reverseCompareTo(OUStringLiteral const & literal) const {
-        return rtl_ustr_reverseCompare_WithLength(
-            pData->buffer, pData->length, literal.data, literal.size);
-    }
-#endif
-
     /**
       Perform a comparison of two strings.
 
@@ -865,6 +853,14 @@ public:
       @return   true if the strings are equal;
                 false, otherwise.
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool equalsIgnoreAsciiCase(std::u16string_view sv) const {
+        return
+            rtl_ustr_compareIgnoreAsciiCase_WithLength(
+                pData->buffer, pData->length, sv.data(), sv.size())
+            == 0;
+    }
+#else
     bool equalsIgnoreAsciiCase( const OUString & str ) const
     {
         if ( pData->length != str.pData->length )
@@ -874,6 +870,7 @@ public:
         return rtl_ustr_compareIgnoreAsciiCase_WithLength( pData->buffer, pData->length,
                                                            str.pData->buffer, str.pData->length ) == 0;
     }
+#endif
 
     /**
       Perform an ASCII lowercase comparison of two strings.
@@ -890,12 +887,18 @@ public:
 
       @since LibreOffice 4.0
     */
+#if defined LIBO_INTERNAL_ONLY
+    sal_Int32 compareToIgnoreAsciiCase(std::u16string_view sv) const {
+        return rtl_ustr_compareIgnoreAsciiCase_WithLength(
+            pData->buffer, pData->length, sv.data(), sv.size());
+    }
+#else
     sal_Int32 compareToIgnoreAsciiCase( const OUString & str ) const
     {
         return rtl_ustr_compareIgnoreAsciiCase_WithLength( pData->buffer, pData->length,
                                                            str.pData->buffer, str.pData->length );
     }
-
+#endif
 
     /**
      @overload
@@ -917,29 +920,6 @@ public:
                 == 0);
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    equalsIgnoreAsciiCase(T & literal) const {
-        return
-            rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                pData->buffer, pData->length,
-                libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                    literal),
-                libreoffice_internal::ConstCharArrayDetector<T>::length)
-            == 0;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool equalsIgnoreAsciiCase(OUStringLiteral const & literal) const {
-        return
-            rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                pData->buffer, pData->length, literal.data, literal.size)
-            == 0;
-    }
-#endif
-
    /**
       Match against a substring appearing in this string.
 
@@ -955,11 +935,21 @@ public:
                 at the given position;
                 false, otherwise.
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool match(std::u16string_view sv, sal_Int32 fromIndex = 0) const {
+        return
+            rtl_ustr_shortenedCompare_WithLength(
+                pData->buffer + fromIndex, pData->length - fromIndex, sv.data(), sv.size(),
+                sv.size())
+            == 0;
+    }
+#else
     bool match( const OUString & str, sal_Int32 fromIndex = 0 ) const
     {
         return rtl_ustr_shortenedCompare_WithLength( pData->buffer+fromIndex, pData->length-fromIndex,
                                                      str.pData->buffer, str.pData->length, str.pData->length ) == 0;
     }
+#endif
 
     /**
      @overload
@@ -980,32 +970,6 @@ public:
             == 0;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    match(T & literal, sal_Int32 fromIndex = 0) const {
-        assert(fromIndex >= 0);
-        return
-            rtl_ustr_shortenedCompare_WithLength(
-                pData->buffer + fromIndex, pData->length - fromIndex,
-                libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                    literal),
-                libreoffice_internal::ConstCharArrayDetector<T>::length,
-                libreoffice_internal::ConstCharArrayDetector<T>::length)
-            == 0;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool match(OUStringLiteral const & literal, sal_Int32 fromIndex = 0) const {
-        return
-            rtl_ustr_shortenedCompare_WithLength(
-                pData->buffer + fromIndex, pData->length - fromIndex,
-                literal.data, literal.size, literal.size)
-            == 0;
-    }
-#endif
-
     /**
       Match against a substring appearing in this string, ignoring the case of
       ASCII letters.
@@ -1024,12 +988,22 @@ public:
                 at the given position;
                 false, otherwise.
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool matchIgnoreAsciiCase(std::u16string_view sv, sal_Int32 fromIndex = 0) const {
+        return
+            rtl_ustr_shortenedCompareIgnoreAsciiCase_WithLength(
+                pData->buffer + fromIndex, pData->length - fromIndex, sv.data(), sv.size(),
+                sv.size())
+            == 0;
+    }
+#else
     bool matchIgnoreAsciiCase( const OUString & str, sal_Int32 fromIndex = 0 ) const
     {
         return rtl_ustr_shortenedCompareIgnoreAsciiCase_WithLength( pData->buffer+fromIndex, pData->length-fromIndex,
                                                                     str.pData->buffer, str.pData->length,
                                                                     str.pData->length ) == 0;
     }
+#endif
 
     /**
      @overload
@@ -1050,34 +1024,6 @@ public:
             == 0;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    matchIgnoreAsciiCase(T & literal, sal_Int32 fromIndex = 0) const {
-        assert(fromIndex >= 0);
-        return
-            rtl_ustr_shortenedCompareIgnoreAsciiCase_WithLength(
-                pData->buffer + fromIndex, pData->length - fromIndex,
-                libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                    literal),
-                libreoffice_internal::ConstCharArrayDetector<T>::length,
-                libreoffice_internal::ConstCharArrayDetector<T>::length)
-            == 0;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool matchIgnoreAsciiCase(
-        OUStringLiteral const & literal, sal_Int32 fromIndex = 0) const
-    {
-        return
-            rtl_ustr_shortenedCompareIgnoreAsciiCase_WithLength(
-                pData->buffer+fromIndex, pData->length-fromIndex, literal.data,
-                literal.size, literal.size)
-            == 0;
-    }
-#endif
-
     /**
       Compares two strings.
 
@@ -1363,6 +1309,15 @@ public:
 
       @since LibreOffice 4.0
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool startsWith(std::u16string_view sv, OUString * rest = nullptr) const {
+        auto const b = match(sv);
+        if (b && rest != nullptr) {
+            *rest = copy(sv.size());
+        }
+        return b;
+    }
+#else
     bool startsWith(OUString const & str, OUString * rest = NULL) const {
         bool b = match(str);
         if (b && rest != NULL) {
@@ -1370,6 +1325,7 @@ public:
         }
         return b;
     }
+#endif
 
     /**
      @overload
@@ -1397,43 +1353,6 @@ public:
         return b;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    startsWith(T & literal, OUString * rest = nullptr) const {
-        bool b
-            = (libreoffice_internal::ConstCharArrayDetector<T>::length
-               <= sal_uInt32(pData->length))
-            && (rtl_ustr_reverseCompare_WithLength(
-                    pData->buffer,
-                    libreoffice_internal::ConstCharArrayDetector<T>::length,
-                    libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                        literal),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(
-                libreoffice_internal::ConstCharArrayDetector<T>::length);
-        }
-        return b;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool startsWith(OUStringLiteral const & literal, OUString * rest = nullptr)
-        const
-    {
-        bool b = literal.size <= pData->length
-            && (rtl_ustr_reverseCompare_WithLength(
-                    pData->buffer, literal.size, literal.data, literal.size)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(literal.size);
-        }
-        return b;
-    }
-#endif
-
     /**
       Check whether this string starts with a given string, ignoring the case of
       ASCII letters.
@@ -1454,6 +1373,15 @@ public:
 
       @since LibreOffice 4.0
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool startsWithIgnoreAsciiCase(std::u16string_view sv, OUString * rest = nullptr) const {
+        auto const b = matchIgnoreAsciiCase(sv);
+        if (b && rest != nullptr) {
+            *rest = copy(sv.size());
+        }
+        return b;
+    }
+#else
     bool startsWithIgnoreAsciiCase(OUString const & str, OUString * rest = NULL)
         const
     {
@@ -1463,6 +1391,7 @@ public:
         }
         return b;
     }
+#endif
 
     /**
      @overload
@@ -1490,43 +1419,6 @@ public:
         return b;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    startsWithIgnoreAsciiCase(T & literal, OUString * rest = nullptr) const {
-        bool b
-            = (libreoffice_internal::ConstCharArrayDetector<T>::length
-               <= sal_uInt32(pData->length))
-            && (rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                    pData->buffer,
-                    libreoffice_internal::ConstCharArrayDetector<T>::length,
-                    libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                        literal),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(
-                libreoffice_internal::ConstCharArrayDetector<T>::length);
-        }
-        return b;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool startsWithIgnoreAsciiCase(
-        OUStringLiteral const & literal, OUString * rest = nullptr) const
-    {
-        bool b
-            = (rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                   pData->buffer, literal.size, literal.data, literal.size)
-               == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(literal.size);
-        }
-        return b;
-    }
-#endif
-
     /**
       Check whether this string ends with a given substring.
 
@@ -1541,6 +1433,16 @@ public:
 
       @since LibreOffice 3.6
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool endsWith(std::u16string_view sv, OUString * rest = nullptr) const {
+        auto const b = sv.size() <= sal_uInt32(pData->length)
+            && match(sv, pData->length - sv.size());
+        if (b && rest != nullptr) {
+            *rest = copy(0, (pData->length - sv.size()));
+        }
+        return b;
+    }
+#else
     bool endsWith(OUString const & str, OUString * rest = NULL) const {
         bool b = str.getLength() <= getLength()
             && match(str, getLength() - str.getLength());
@@ -1549,6 +1451,7 @@ public:
         }
         return b;
     }
+#endif
 
     /**
      @overload
@@ -1579,47 +1482,6 @@ public:
         return b;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    endsWith(T & literal, OUString * rest = nullptr) const {
-        bool b
-            = (libreoffice_internal::ConstCharArrayDetector<T>::length
-               <= sal_uInt32(pData->length))
-            && (rtl_ustr_reverseCompare_WithLength(
-                    (pData->buffer + pData->length
-                     - libreoffice_internal::ConstCharArrayDetector<T>::length),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length,
-                    libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                        literal),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(
-                0,
-                (getLength()
-                 - libreoffice_internal::ConstCharArrayDetector<T>::length));
-        }
-        return b;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool endsWith(OUStringLiteral const & literal, OUString * rest = nullptr)
-        const
-    {
-        bool b = literal.size <= pData->length
-            && (rtl_ustr_reverseCompare_WithLength(
-                    pData->buffer + pData->length - literal.size, literal.size,
-                    literal.data, literal.size)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(0, (getLength() - literal.size));
-        }
-        return b;
-    }
-#endif
-
     /**
       Check whether this string ends with a given ASCII string.
 
@@ -1660,6 +1522,16 @@ public:
 
       @since LibreOffice 3.6
     */
+#if defined LIBO_INTERNAL_ONLY
+    bool endsWithIgnoreAsciiCase(std::u16string_view sv, OUString * rest = nullptr) const {
+        auto const b = sv.size() <= sal_uInt32(pData->length)
+            && matchIgnoreAsciiCase(sv, pData->length - sv.size());
+        if (b && rest != nullptr) {
+            *rest = copy(0, pData->length - sv.size());
+        }
+        return b;
+    }
+#else
     bool endsWithIgnoreAsciiCase(OUString const & str, OUString * rest = NULL) const
     {
         bool b =  str.getLength() <= getLength()
@@ -1669,6 +1541,7 @@ public:
         }
         return b;
     }
+#endif
 
     /**
      @overload
@@ -1701,47 +1574,6 @@ public:
         return b;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename libreoffice_internal::ConstCharArrayDetector<T, bool>::TypeUtf16
-    endsWithIgnoreAsciiCase(T & literal, OUString * rest = nullptr) const {
-        bool b
-            = (libreoffice_internal::ConstCharArrayDetector<T>::length
-               <= sal_uInt32(pData->length))
-            && (rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                    (pData->buffer + pData->length
-                     - libreoffice_internal::ConstCharArrayDetector<T>::length),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length,
-                    libreoffice_internal::ConstCharArrayDetector<T>::toPointer(
-                        literal),
-                    libreoffice_internal::ConstCharArrayDetector<T>::length)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(
-                0,
-                (getLength()
-                 - libreoffice_internal::ConstCharArrayDetector<T>::length));
-        }
-        return b;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    bool endsWithIgnoreAsciiCase(
-        OUStringLiteral const & literal, OUString * rest = nullptr) const
-    {
-        bool b = literal.size <= pData->length
-            && (rtl_ustr_compareIgnoreAsciiCase_WithLength(
-                    pData->buffer + pData->length - literal.size,
-                    literal.size, literal.data, literal.size)
-                == 0);
-        if (b && rest != nullptr) {
-            *rest = copy(0, getLength() - literal.size);
-        }
-        return b;
-    }
-#endif
-
     /**
       Check whether this string ends with a given ASCII string, ignoring the
       case of ASCII letters.
@@ -2105,12 +1937,20 @@ public:
                 returned. If it does not occur as a substring starting
                 at fromIndex or beyond, -1 is returned.
     */
+#if defined LIBO_INTERNAL_ONLY
+    sal_Int32 indexOf(std::u16string_view sv, sal_Int32 fromIndex = 0) const {
+        auto const n = rtl_ustr_indexOfStr_WithLength(
+            pData->buffer + fromIndex, pData->length - fromIndex, sv.data(), sv.size());
+        return n < 0 ? n : n + fromIndex;
+    }
+#else
     sal_Int32 indexOf( const OUString & str, sal_Int32 fromIndex = 0 ) const
     {
         sal_Int32 ret = rtl_ustr_indexOfStr_WithLength( pData->buffer+fromIndex, pData->length-fromIndex,
                                                         str.pData->buffer, str.pData->length );
         return (ret < 0 ? ret : ret+fromIndex);
     }
+#endif
 
     /**
      @overload
@@ -2129,31 +1969,6 @@ public:
         return n < 0 ? n : n + fromIndex;
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, sal_Int32>::TypeUtf16
-    indexOf(T & literal, sal_Int32 fromIndex = 0) const {
-        assert(fromIndex >= 0);
-        auto n = rtl_ustr_indexOfStr_WithLength(
-            pData->buffer + fromIndex, pData->length - fromIndex,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(literal),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-        return n < 0 ? n : n + fromIndex;
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    sal_Int32 indexOf(OUStringLiteral const & literal, sal_Int32 fromIndex = 0)
-        const
-    {
-        sal_Int32 n = rtl_ustr_indexOfStr_WithLength(
-            pData->buffer + fromIndex, pData->length - fromIndex, literal.data,
-            literal.size);
-        return n < 0 ? n : n + fromIndex;
-    }
-#endif
-
     /**
        Returns the index within this string of the first occurrence of the
        specified ASCII substring, starting at the specified index.
@@ -2208,11 +2023,18 @@ public:
                 the last such substring is returned. If it does not occur as
                 a substring, -1 is returned.
     */
+#if defined LIBO_INTERNAL_ONLY
+    sal_Int32 lastIndexOf(std::u16string_view sv) const {
+        return rtl_ustr_lastIndexOfStr_WithLength(
+            pData->buffer, pData->length, sv.data(), sv.size());
+    }
+#else
     sal_Int32 lastIndexOf( const OUString & str ) const
     {
         return rtl_ustr_lastIndexOfStr_WithLength( pData->buffer, pData->length,
                                                    str.pData->buffer, str.pData->length );
     }
+#endif
 
     /**
       Returns the index within this string of the last occurrence of
@@ -2231,11 +2053,17 @@ public:
                 of the first character of the last such substring is
                 returned. Otherwise, -1 is returned.
     */
+#if defined LIBO_INTERNAL_ONLY
+    sal_Int32 lastIndexOf(std::u16string_view sv, sal_Int32 fromIndex) const {
+        return rtl_ustr_lastIndexOfStr_WithLength(pData->buffer, fromIndex, sv.data(), sv.size());
+    }
+#else
     sal_Int32 lastIndexOf( const OUString & str, sal_Int32 fromIndex ) const
     {
         return rtl_ustr_lastIndexOfStr_WithLength( pData->buffer, fromIndex,
                                                    str.pData->buffer, str.pData->length );
     }
+#endif
 
     /**
      @overload
@@ -2253,25 +2081,6 @@ public:
             libreoffice_internal::ConstCharArrayDetector<T>::length);
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T>
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, sal_Int32>::TypeUtf16
-    lastIndexOf(T & literal) const {
-        return rtl_ustr_lastIndexOfStr_WithLength(
-            pData->buffer, pData->length,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(literal),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    sal_Int32 lastIndexOf(OUStringLiteral const & literal) const {
-        return rtl_ustr_lastIndexOfStr_WithLength(
-            pData->buffer, pData->length, literal.data, literal.size);
-    }
-#endif
-
     /**
        Returns the index within this string of the last occurrence of the
        specified ASCII substring.
@@ -2411,6 +2220,18 @@ public:
 
       @since LibreOffice 3.6
     */
+#if defined LIBO_INTERNAL_ONLY
+    [[nodiscard]] OUString replaceFirst(
+        std::u16string_view from, std::u16string_view to, sal_Int32 * index = nullptr) const
+    {
+        rtl_uString * s = nullptr;
+        sal_Int32 i = 0;
+        rtl_uString_newReplaceFirstUtf16LUtf16L(
+            &s, pData, from.data(), from.size(), to.data(), to.size(),
+            index == nullptr ? &i : index);
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     SAL_WARN_UNUSED_RESULT OUString replaceFirst(
         OUString const & from, OUString const & to, sal_Int32 * index = NULL) const
     {
@@ -2420,6 +2241,7 @@ public:
             &s, pData, from.pData, to.pData, index == NULL ? &i : index);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing the first occurrence of a
@@ -2439,6 +2261,21 @@ public:
 
       @since LibreOffice 3.6
     */
+#if defined LIBO_INTERNAL_ONLY
+    template<typename T> [[nodiscard]]
+    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type replaceFirst(
+        T & from, std::u16string_view to, sal_Int32 * index = nullptr) const
+    {
+        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
+        rtl_uString * s = nullptr;
+        sal_Int32 i = 0;
+        rtl_uString_newReplaceFirstAsciiLUtf16L(
+            &s, pData, libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
+            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data(), to.size(),
+            index == nullptr ? &i : index);
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     template< typename T >
     SAL_WARN_UNUSED_RESULT typename libreoffice_internal::ConstCharArrayDetector< T, OUString >::Type replaceFirst( T& from, OUString const & to,
                                                                                                         sal_Int32 * index = NULL) const
@@ -2453,6 +2290,7 @@ public:
             index == NULL ? &i : index);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing the first occurrence of a
@@ -2472,6 +2310,21 @@ public:
 
       @since LibreOffice 5.1
     */
+#if defined LIBO_INTERNAL_ONLY
+    template<typename T> [[nodiscard]]
+    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type replaceFirst(
+        std::u16string_view from, T & to, sal_Int32 * index = nullptr) const
+    {
+        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
+        rtl_uString * s = nullptr;
+        sal_Int32 i = 0;
+        rtl_uString_newReplaceFirstUtf16LAsciiL(
+            &s, pData, from.data(), from.size(),
+            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
+            libreoffice_internal::ConstCharArrayDetector<T>::length, index == nullptr ? &i : index);
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     template< typename T >
     SAL_WARN_UNUSED_RESULT typename libreoffice_internal::ConstCharArrayDetector< T, OUString >::Type replaceFirst( OUString const & from, T& to,
                                                                                                         sal_Int32 * index = NULL) const
@@ -2486,6 +2339,7 @@ public:
             index == NULL ? &i : index);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing the first occurrence of a
@@ -2523,224 +2377,6 @@ public:
         return OUString(s, SAL_NO_ACQUIRE);
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString>::TypeUtf16
-    replaceFirst(T & from, OUString const & to, sal_Int32 * index = nullptr)
-        const
-    {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length,
-            to.pData->buffer, to.pData->length, index == nullptr ? &i : index);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString>::TypeUtf16
-    replaceFirst(OUString const & from, T & to, sal_Int32 * index = nullptr)
-        const
-    {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData, from.pData->buffer, from.pData->length,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length,
-            index == nullptr ? &i : index);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::TypeUtf16
-        >::TypeUtf16
-    replaceFirst(T1 & from, T2 & to, sal_Int32 * index = nullptr) const {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length,
-            index == nullptr ? &i : index);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::Type
-        >::TypeUtf16
-    replaceFirst(T1 & from, T2 & to, sal_Int32 * index = nullptr) const {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LAsciiL(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length,
-            index == nullptr ? &i : index);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::TypeUtf16
-        >::Type
-    replaceFirst(T1 & from, T2 & to, sal_Int32 * index = nullptr) const {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstAsciiLUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length,
-            index == nullptr ? &i : index);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceFirst(
-        OUStringLiteral const & from, OUString const & to,
-        sal_Int32 * index = nullptr) const
-    {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData, from.data, from.size, to.pData->buffer, to.pData->length,
-            index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceFirst(
-        OUString const & from, OUStringLiteral const & to,
-        sal_Int32 * index = nullptr) const
-    {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData, from.pData->buffer, from.pData->length, to.data, to.size,
-            index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceFirst(
-        OUStringLiteral const & from, OUStringLiteral const & to,
-        sal_Int32 * index = nullptr) const
-    {
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData, from.data, from.size, to.data, to.size,
-            index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type
-    replaceFirst(
-        OUStringLiteral const & from, T & to, sal_Int32 * index = nullptr) const
-    {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LAsciiL(
-            &s, pData, from.data, from.size,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length,
-            index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type
-    replaceFirst(
-        T & from, OUStringLiteral const & to, sal_Int32 * index = nullptr) const
-    {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstAsciiLUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data,
-            to.size, index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString >::TypeUtf16
-    replaceFirst(
-        OUStringLiteral const & from, T & to, sal_Int32 * index = nullptr) const
-    {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData, from.data, from.size,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length,
-            index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString >::TypeUtf16
-    replaceFirst(
-        T & from, OUStringLiteral const & to, sal_Int32 * index = nullptr) const
-    {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
-        rtl_uString * s = nullptr;
-        sal_Int32 i = 0;
-        rtl_uString_newReplaceFirstUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data,
-            to.size, index == nullptr ? &i : index);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-#endif
-
     /**
       Returns a new string resulting from replacing all occurrences of a given
       substring with another substring.
@@ -2756,6 +2392,16 @@ public:
 
       @since LibreOffice 4.0
     */
+#if defined LIBO_INTERNAL_ONLY
+    [[nodiscard]] OUString replaceAll(
+        std::u16string_view from, std::u16string_view to, sal_Int32 fromIndex = 0) const
+    {
+        rtl_uString * s = nullptr;
+        rtl_uString_newReplaceAllFromIndexUtf16LUtf16L(
+            &s, pData, from.data(), from.size(), to.data(), to.size(), fromIndex);
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     SAL_WARN_UNUSED_RESULT OUString replaceAll(
         OUString const & from, OUString const & to, sal_Int32 fromIndex = 0) const
     {
@@ -2763,6 +2409,7 @@ public:
         rtl_uString_newReplaceAllFromIndex(&s, pData, from.pData, to.pData, fromIndex);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing all occurrences of a given
@@ -2777,6 +2424,19 @@ public:
 
       @since LibreOffice 3.6
     */
+#if defined LIBO_INTERNAL_ONLY
+    template<typename T> [[nodiscard]]
+    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type replaceAll(
+        T & from, std::u16string_view to) const
+    {
+        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
+        rtl_uString * s = nullptr;
+        rtl_uString_newReplaceAllAsciiLUtf16L(
+            &s, pData, libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
+            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data(), to.size());
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     template< typename T >
     SAL_WARN_UNUSED_RESULT typename libreoffice_internal::ConstCharArrayDetector< T, OUString >::Type replaceAll( T& from, OUString const & to) const
     {
@@ -2788,6 +2448,7 @@ public:
             libreoffice_internal::ConstCharArrayDetector<T>::length, to.pData);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing all occurrences of a given
@@ -2802,6 +2463,20 @@ public:
 
       @since LibreOffice 5.1
     */
+#if defined LIBO_INTERNAL_ONLY
+    template<typename T> [[nodiscard]]
+    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type replaceAll(
+        std::u16string_view from, T & to) const
+    {
+        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
+        rtl_uString * s = nullptr;
+        rtl_uString_newReplaceAllUtf16LAsciiL(
+            &s, pData, from.data(), from.size(),
+            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
+            libreoffice_internal::ConstCharArrayDetector<T>::length);
+        return OUString(s, SAL_NO_ACQUIRE);
+    }
+#else
     template< typename T >
     SAL_WARN_UNUSED_RESULT typename libreoffice_internal::ConstCharArrayDetector< T, OUString >::Type replaceAll( OUString const & from, T& to) const
     {
@@ -2813,6 +2488,7 @@ public:
             libreoffice_internal::ConstCharArrayDetector<T>::length);
         return OUString(s, SAL_NO_ACQUIRE);
     }
+#endif
 
     /**
       Returns a new string resulting from replacing all occurrences of a given
@@ -2843,188 +2519,6 @@ public:
         return OUString(s, SAL_NO_ACQUIRE);
     }
 
-#if defined LIBO_INTERNAL_ONLY
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString>::TypeUtf16
-    replaceAll(T & from, OUString const & to) const {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length,
-            to.pData->buffer, to.pData->length);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString>::TypeUtf16
-    replaceAll(OUString const & from, T & to) const {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData, from.pData->buffer, from.pData->length,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::TypeUtf16
-        >::TypeUtf16
-    replaceAll(T1 & from, T2 & to) const {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::Type
-        >::TypeUtf16
-    replaceAll(T1 & from, T2 & to) const {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LAsciiL(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.3 */
-    template<typename T1, typename T2> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<
-            T1,
-            typename libreoffice_internal::ConstCharArrayDetector<
-                T2, OUString>::TypeUtf16
-        >::Type
-    replaceAll(T1 & from, T2 & to) const {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllAsciiLUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T1>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T1>::length,
-            libreoffice_internal::ConstCharArrayDetector<T2>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T2>::length);
-        if (s == nullptr) {
-            throw std::bad_alloc();
-                // should be std::length_error if resulting would be too large
-        }
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceAll(
-        OUStringLiteral const & from, OUString const & to) const
-    {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData, from.data, from.size, to.pData->buffer, to.pData->length);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceAll(
-        OUString const & from, OUStringLiteral const & to) const
-    {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData, from.pData->buffer, from.pData->length, to.data, to.size);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    [[nodiscard]] OUString replaceAll(
-        OUStringLiteral const & from, OUStringLiteral const & to) const
-    {
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData, from.data, from.size, to.data, to.size);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type
-    replaceAll(OUStringLiteral const & from, T & to) const {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LAsciiL(
-            &s, pData, from.data, from.size,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename libreoffice_internal::ConstCharArrayDetector<T, OUString >::Type
-    replaceAll(T & from, OUStringLiteral const & to) const {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllAsciiLUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data,
-            to.size);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString >::TypeUtf16
-    replaceAll(OUStringLiteral const & from, T & to) const {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(to));
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData, from.data, from.size,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(to),
-            libreoffice_internal::ConstCharArrayDetector<T>::length);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-    /** @overload @since LibreOffice 5.4 */
-    template<typename T> [[nodiscard]]
-    typename
-        libreoffice_internal::ConstCharArrayDetector<T, OUString >::TypeUtf16
-    replaceAll(T & from, OUStringLiteral const & to) const {
-        assert(libreoffice_internal::ConstCharArrayDetector<T>::isValid(from));
-        rtl_uString * s = nullptr;
-        rtl_uString_newReplaceAllUtf16LUtf16L(
-            &s, pData,
-            libreoffice_internal::ConstCharArrayDetector<T>::toPointer(from),
-            libreoffice_internal::ConstCharArrayDetector<T>::length, to.data,
-            to.size);
-        return OUString(s, SAL_NO_ACQUIRE);
-    }
-#endif
-
     /**
       Converts from this string all ASCII uppercase characters (65-90)
       to ASCII lowercase characters (97-122).
diff --git a/sal/CompilerTest_sal_rtl_oustring.mk b/sal/CompilerTest_sal_rtl_oustring.mk
new file mode 100644
index 000000000000..fb77d89048a6
--- /dev/null
+++ b/sal/CompilerTest_sal_rtl_oustring.mk
@@ -0,0 +1,16 @@
+# -*- Mode: makefile-gmake; tab-width: 4; indent-tabs-mode: t; fill-column: 100 -*-
+#
+# This file is part of the LibreOffice project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+
+$(eval $(call gb_CompilerTest_CompilerTest,sal_rtl_oustring))
+
+$(eval $(call gb_CompilerTest_add_exception_objects,sal_rtl_oustring, \
+    sal/qa/rtl/strings/compile-oustring \
+))
+
+# vim: set noet sw=4 ts=4:
diff --git a/sal/Module_sal.mk b/sal/Module_sal.mk
index 4d7a84ee4e61..7611bc950f07 100644
--- a/sal/Module_sal.mk
+++ b/sal/Module_sal.mk
@@ -30,6 +30,8 @@ $(eval $(call gb_Module_add_check_targets,sal,\
 	CppunitTest_sal_osl \
 	CppunitTest_sal_rtl \
 	CppunitTest_sal_types \
+	$(if $(COM_IS_CLANG),$(if $(COMPILER_EXTERNAL_TOOL)$(COMPILER_PLUGIN_TOOL),, \
+	    CompilerTest_sal_rtl_oustring)) \
 ))
 
 endif
diff --git a/sal/qa/rtl/strings/compile-oustring.cxx b/sal/qa/rtl/strings/compile-oustring.cxx
new file mode 100644
index 000000000000..667a52324e4e
--- /dev/null
+++ b/sal/qa/rtl/strings/compile-oustring.cxx
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <sal/config.h>
+
+#include <rtl/string.h>
+#include <rtl/ustring.hxx>
+
+// expected-note@rtl/ustring.hxx:* 1+ {{}}
+
+void checkExtraIntArgument()
+{
+    // This makes sure that using by mistake RTL_CONSTASCII_STRINGPARAM does not trigger a different
+    // overload, i.e. the second argument to match() in this case is the indexFrom argument,
+    // but with the macro it would contain the length of the string. Therefore
+    // match( RTL_CONSTASCII_STRINGPARAM( "bar" )) would be match( "bar", 3 ), which would be
+    // true when called for OUString( "foobar" ). But this should not happen because of the
+    // &foo[0] trick in the RTL_CONSTASCII_STRINGPARAM macro.
+    // expected-error@+1 {{}}
+    OUString("foobar").match(RTL_CONSTASCII_STRINGPARAM("bar"));
+}
+
+void checkNonconstChar()
+{
+    // check that non-const char[] data do not trigger string literal overloads
+    char test[] = "test";
+    char bar[] = "bar";
+    const char consttest[] = "test";
+    const char constbar[] = "bar";
+    // expected-error@+1 {{}}
+    (void)OUString("footest").replaceAll(test, bar);
+    // expected-error@+1 {{}}
+    (void)OUString("footest").replaceAll(consttest, bar);
+    // expected-error@+1 {{}}
+    (void)OUString("footest").replaceAll(test, constbar);
+    (void)OUString("footest").replaceAll(consttest, constbar);
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */
diff --git a/sal/qa/rtl/strings/test_oustring_compare.cxx b/sal/qa/rtl/strings/test_oustring_compare.cxx
index c06d40c4d653..6316f09b1d58 100644
--- a/sal/qa/rtl/strings/test_oustring_compare.cxx
+++ b/sal/qa/rtl/strings/test_oustring_compare.cxx
@@ -67,12 +67,12 @@ void test::oustring::Compare::compareToIgnoreAsciiCase()
 {
     CPPUNIT_ASSERT_EQUAL(
         sal_Int32(0),
-        OUString("abc").compareToIgnoreAsciiCase("ABC"));
+        OUString("abc").compareToIgnoreAsciiCase(u"ABC"));
     CPPUNIT_ASSERT(
-        OUString("ABC").compareToIgnoreAsciiCase("abcdef")
+        OUString("ABC").compareToIgnoreAsciiCase(u"abcdef")
         < 0);
     CPPUNIT_ASSERT(
-        OUString("A").compareToIgnoreAsciiCase("_") > 0);
+        OUString("A").compareToIgnoreAsciiCase(u"_") > 0);
 }
 
 void test::oustring::Compare::compareTo()
diff --git a/sal/qa/rtl/strings/test_oustring_stringliterals.cxx b/sal/qa/rtl/strings/test_oustring_stringliterals.cxx
index 4ba1b04067d4..a1c79f8cc9e5 100644
--- a/sal/qa/rtl/strings/test_oustring_stringliterals.cxx
+++ b/sal/qa/rtl/strings/test_oustring_stringliterals.cxx
@@ -12,6 +12,8 @@
 
 #include <sal/config.h>
 
+#include <string>
+#include <string_view>
 #include <utility>
 
 #include <o3tl/cppunittraitshelper.hxx>
@@ -33,12 +35,11 @@ class StringLiterals: public CppUnit::TestFixture
 private:
     void checkCtors();
     void checkUsage();
-    void checkExtraIntArgument();
-    void checkNonconstChar();
     void checkBuffer();
     void checkOUStringLiteral();
     void checkOUStringChar();
     void checkUtf16();
+    void checkEmbeddedNul();
 
     void testcall( const char str[] );
 
@@ -48,12 +49,11 @@ private:
 CPPUNIT_TEST_SUITE(StringLiterals);
 CPPUNIT_TEST(checkCtors);
 CPPUNIT_TEST(checkUsage);
-CPPUNIT_TEST(checkExtraIntArgument);
-CPPUNIT_TEST(checkNonconstChar);
 CPPUNIT_TEST(checkBuffer);
 CPPUNIT_TEST(checkOUStringLiteral);
 CPPUNIT_TEST(checkOUStringChar);
 CPPUNIT_TEST(checkUtf16);
+CPPUNIT_TEST(checkEmbeddedNul);
 CPPUNIT_TEST_SUITE_END();
 };
 
@@ -157,40 +157,6 @@ void test::oustring::StringLiterals::checkUsage()
     CPPUNIT_ASSERT( !rtl_string_unittest_const_literal );
 }
 
-void test::oustring::StringLiterals::checkExtraIntArgument()
-{
-    // This makes sure that using by mistake RTL_CONSTASCII_STRINGPARAM does not trigger a different
-    // overload, i.e. the second argument to match() in this case is the indexFrom argument,
-    // but with the macro it would contain the length of the string. Therefore
-    // match( RTL_CONSTASCII_STRINGPARAM( "bar" )) would be match( "bar", 3 ), which would be
-    // true when called for OUString( "foobar" ). But this should not happen because of the
-    // &foo[0] trick in the RTL_CONSTASCII_STRINGPARAM macro.
-    CPPUNIT_ASSERT( !rtl::OUString("foobar").match( "bar" ));
-    CPPUNIT_ASSERT( !rtl::OUString("foobar").match( RTL_CONSTASCII_STRINGPARAM( "bar" )));
-}
-
-void test::oustring::StringLiterals::checkNonconstChar()
-{ // check that non-const char[] data do not trigger string literal overloads
-    CPPUNIT_ASSERT_EQUAL( rtl::OUString( "foobar" ), rtl::OUString( "footest" ).replaceAll( "test", "bar" ));
-    char test[] = "test";
-    char bar[] = "bar";
-    const char consttest[] = "test";
-    const char constbar[] = "bar";
-    CPPUNIT_ASSERT(
-        !VALID_CONVERSION_CALL(
-            [&test, &bar]() {
-                return rtl::OUString("footest").replaceAll(test, bar); }));
-    CPPUNIT_ASSERT(
-        !VALID_CONVERSION_CALL(
-            [&consttest, &bar]() {
-                return rtl::OUString("footest").replaceAll(consttest, bar); }));
-    CPPUNIT_ASSERT(
-        !VALID_CONVERSION_CALL(
-            [&test, &constbar]() {
-                return rtl::OUString("footest").replaceAll(test, constbar); }));
-    CPPUNIT_ASSERT_EQUAL( rtl::OUString( "foobar" ), rtl::OUString( "footest" ).replaceAll( consttest, constbar ));
-}
-
 void test::oustring::StringLiterals::checkBuffer()
 {
     rtl::OUStringBuffer buf;
@@ -424,6 +390,20 @@ void test::oustring::StringLiterals::checkUtf16() {
     CPPUNIT_ASSERT_EQUAL(sal_Int32(5), b.lastIndexOf(u"ab"));
 }
 
+void test::oustring::StringLiterals::checkEmbeddedNul() {
+    using namespace std::literals;
+    rtl::OUString const s("foobar");
+    constexpr char16_t const a[] = u"foo\0hidden";
+    char16_t const * const p = a;
+    CPPUNIT_ASSERT(s.startsWith(a));
+    CPPUNIT_ASSERT(s.startsWith(p));
+    CPPUNIT_ASSERT(s.startsWith(u"foo\0hidden"));
+    CPPUNIT_ASSERT(!s.startsWith(u"foo\0hidden"s));
+    CPPUNIT_ASSERT(!s.startsWith(u"foo\0hidden"sv));
+    CPPUNIT_ASSERT(!s.startsWith(rtlunittest::OUStringLiteral(a)));
+    CPPUNIT_ASSERT(!s.startsWith(rtlunittest::OUStringLiteral(u"foo\0hidden")));
+}
+
 } // namespace
 
 CPPUNIT_TEST_SUITE_REGISTRATION(test::oustring::StringLiterals);
diff --git a/sal/qa/rtl/strings/test_strings_replace.cxx b/sal/qa/rtl/strings/test_strings_replace.cxx
index a27f5f14286b..3be6e176ad41 100644
--- a/sal/qa/rtl/strings/test_strings_replace.cxx
+++ b/sal/qa/rtl/strings/test_strings_replace.cxx
@@ -273,6 +273,9 @@ void Test::ustringReplaceAll() {
     CPPUNIT_ASSERT_EQUAL(
         OUString("xxa"),
         OUString("xaa").replaceAll(s_xa, s_xx));
+
+    CPPUNIT_ASSERT_EQUAL(
+        OUString("foobarbaz"), OUString("foobarfoo").replaceAll(u"foo", u"baz", 1));
 }
 
 void Test::ustringReplaceAllAsciiL() {
diff --git a/sal/rtl/ustring.cxx b/sal/rtl/ustring.cxx
index d3bf1daedc78..cbadddc6a98e 100644
--- a/sal/rtl/ustring.cxx
+++ b/sal/rtl/ustring.cxx
@@ -1547,10 +1547,19 @@ void rtl_uString_newReplaceAllUtf16LUtf16L(
     rtl_uString ** newStr, rtl_uString * str, sal_Unicode const * from,
     sal_Int32 fromLength, sal_Unicode const * to, sal_Int32 toLength)
     SAL_THROW_EXTERN_C()
+{
+    rtl_uString_newReplaceAllFromIndexUtf16LUtf16L(newStr, str, from, fromLength, to, toLength, 0);
+}
+
+void rtl_uString_newReplaceAllFromIndexUtf16LUtf16L(
+    rtl_uString ** newStr, rtl_uString * str, sal_Unicode const * from,
+    sal_Int32 fromLength, sal_Unicode const * to, sal_Int32 toLength, sal_Int32 fromIndex)
+    SAL_THROW_EXTERN_C()
 {
     assert(toLength >= 0);
+    assert(fromIndex >= 0 && fromIndex <= str->length);
     rtl_uString_assign(newStr, str);
-    for (sal_Int32 i = 0;; i += toLength) {
+    for (sal_Int32 i = fromIndex;; i += toLength) {
         rtl_uString_newReplaceFirstUtf16LUtf16L(
             newStr, *newStr, from, fromLength, to, toLength, &i);
         if (i == -1 || *newStr == nullptr) {
diff --git a/sal/util/sal.map b/sal/util/sal.map
index 48d76b1a3802..dbd22c36ee16 100644
--- a/sal/util/sal.map
+++ b/sal/util/sal.map
@@ -749,6 +749,11 @@ PRIVATE_1.6 { # LibreOffice 6.4
         rtl_ustr_toInt64_WithLength;
 } PRIVATE_1.5;
 
+PRIVATE_1.7 { # LibreOffice 7.1
+    global:
+        rtl_uString_newReplaceAllFromIndexUtf16LUtf16L;
+} PRIVATE_1.5;
+
 PRIVATE_textenc.1 { # LibreOffice 3.6
     global:
         _ZN3sal6detail7textenc20convertCharToUnicode*;
diff --git a/sc/source/filter/excel/xecontent.cxx b/sc/source/filter/excel/xecontent.cxx
index 3fdd33784ede..d73683deadd1 100644
--- a/sc/source/filter/excel/xecontent.cxx
+++ b/sc/source/filter/excel/xecontent.cxx
@@ -452,7 +452,7 @@ XclExpHyperlink::XclExpHyperlink( const XclExpRoot& rRoot, const SvxURLField& rU
         mnFlags |= EXC_HLINK_MARK;
 
         OUString location = XclXmlUtils::ToOUString(*mxTextMark);
-        if (!location.isEmpty() && msTarget.endsWith("#" + location))
+        if (!location.isEmpty() && msTarget.endsWith(OUString("#" + location)))
             msTarget = msTarget.copy(0, msTarget.getLength() - location.getLength() - 1);
     }
 
diff --git a/stoc/source/typeconv/convert.cxx b/stoc/source/typeconv/convert.cxx
index 554c13400fdd..e8fe65830a99 100644
--- a/stoc/source/typeconv/convert.cxx
+++ b/stoc/source/typeconv/convert.cxx
@@ -589,7 +589,7 @@ Any SAL_CALL TypeConverter_Impl::convertTo( const Any& rVal, const Type& aDestTy
             for ( nPos = reinterpret_cast<typelib_EnumTypeDescription *>(aEnumTD.get())->nEnumValues; nPos--; )
             {
                 if (o3tl::forceAccess<OUString>(rVal)->equalsIgnoreAsciiCase(
-                        reinterpret_cast<typelib_EnumTypeDescription *>(aEnumTD.get())->ppEnumNames[nPos] ))
+                        OUString::unacquired(&reinterpret_cast<typelib_EnumTypeDescription *>(aEnumTD.get())->ppEnumNames[nPos]) ))
                     break;
             }
         }
diff --git a/svl/source/numbers/zformat.cxx b/svl/source/numbers/zformat.cxx
index b0e90b4916f6..03fe0f68c041 100644
--- a/svl/source/numbers/zformat.cxx
+++ b/svl/source/numbers/zformat.cxx
@@ -5558,7 +5558,7 @@ OUString SvNumberformat::impTransliterateImpl(const OUString& rStr,
     sal_Int32 nField = -1;
     do
     {
-        nField = rNum.GetParams().indexOf(rKeywords[nDateKey] + "=", ++nField);
+        nField = rNum.GetParams().indexOf(OUString(rKeywords[nDateKey] + "="), ++nField);
     }
     while (nField != -1 && nField != 0 &&
             (rNum.GetParams()[nField - 1] != ',' &&
diff --git a/svtools/source/dialogs/PlaceEditDialog.cxx b/svtools/source/dialogs/PlaceEditDialog.cxx
index b41f16072d71..80df9d61c87c 100644
--- a/svtools/source/dialogs/PlaceEditDialog.cxx
+++ b/svtools/source/dialogs/PlaceEditDialog.cxx
@@ -194,7 +194,7 @@ void PlaceEditDialog::InitDetails( )
     auto nSize = std::min(aTypesUrlsList.getLength(), aTypesNamesList.getLength());
     for ( sal_Int32 i = 0; i < nSize; ++i )
     {
-        OUString sUrl = aTypesUrlsList[i].replaceFirst("<host", "<" + SvtResId(STR_SVT_HOST)).replaceFirst("port>",  SvtResId(STR_SVT_PORT) + ">");
+        OUString sUrl = aTypesUrlsList[i].replaceFirst("<host", OUString("<" + SvtResId(STR_SVT_HOST))).replaceFirst("port>",  OUString(SvtResId(STR_SVT_PORT) + ">"));
 
         if ((sUrl == GDRIVE_BASE_URL && bSkipGDrive) ||
             (sUrl.startsWith( ALFRESCO_CLOUD_BASE_URL) && bSkipAlfresco) ||
diff --git a/svx/source/gallery2/gallery1.cxx b/svx/source/gallery2/gallery1.cxx
index 600b8cc01c95..b732294648c8 100644
--- a/svx/source/gallery2/gallery1.cxx
+++ b/svx/source/gallery2/gallery1.cxx
@@ -288,7 +288,7 @@ void Gallery::ImplLoadSubDirs( const INetURLObject& rBaseURL, bool& rbDirIsReadO
         {
             const char *appBundle = [[[NSBundle mainBundle] bundlePath] UTF8String];
             OUString path = rBaseURL.GetURLPath();
-            if( path.startsWith( OUString( appBundle, strlen( appBundle ), RTL_TEXTENCODING_UTF8 ) + "/" ) )
+            if( path.startsWith( OUString(OUString( appBundle, strlen( appBundle ), RTL_TEXTENCODING_UTF8 ) + "/") ) )
                 rbDirIsReadOnly = true;
         }
 #else
diff --git a/sw/source/filter/ww8/ww8par5.cxx b/sw/source/filter/ww8/ww8par5.cxx
index 1897a874582a..2e7546527b73 100644
--- a/sw/source/filter/ww8/ww8par5.cxx
+++ b/sw/source/filter/ww8/ww8par5.cxx
@@ -98,7 +98,7 @@ namespace
     // #120879# - helper method to identify a bookmark name to match the internal TOC bookmark naming convention
     bool IsTOCBookmarkName(const OUString& rName)
     {
-        return rName.startsWith("_Toc") || rName.startsWith(IDocumentMarkAccess::GetCrossRefHeadingBookmarkNamePrefix()+"_Toc");
+        return rName.startsWith("_Toc") || rName.startsWith(OUString(IDocumentMarkAccess::GetCrossRefHeadingBookmarkNamePrefix()+"_Toc"));
     }
 
     OUString EnsureTOCBookmarkName(const OUString& rName)
diff --git a/sw/source/ui/dbui/mmaddressblockpage.cxx b/sw/source/ui/dbui/mmaddressblockpage.cxx
index f83529d4aaa7..20bcb4fd735a 100644
--- a/sw/source/ui/dbui/mmaddressblockpage.cxx
+++ b/sw/source/ui/dbui/mmaddressblockpage.cxx
@@ -632,7 +632,7 @@ bool SwCustomizeAddressBlockDialog::HasItem(sal_Int32 nUserData)
         }
     }
     //search for this entry in the content
-    return m_xDragED->GetText().indexOf("<" + sEntry + ">") >= 0;
+    return m_xDragED->GetText().indexOf(OUString("<" + sEntry + ">")) >= 0;
 }
 
 IMPL_LINK_NOARG(SwCustomizeAddressBlockDialog, SelectionChangedIdleHdl, Timer*, void)
diff --git a/xmlsecurity/source/helper/documentsignaturehelper.cxx b/xmlsecurity/source/helper/documentsignaturehelper.cxx
index 784a5571d2a9..f1c48daa3a0c 100644
--- a/xmlsecurity/source/helper/documentsignaturehelper.cxx
+++ b/xmlsecurity/source/helper/documentsignaturehelper.cxx
@@ -314,7 +314,7 @@ void DocumentSignatureHelper::AppendContentTypes(const uno::Reference<embed::XSt
 
         it = std::find_if(rDefaults.begin(), rDefaults.end(), [&](const beans::StringPair& rPair)
         {
-            return rElement.endsWith("." + rPair.First);
+            return rElement.endsWith(OUString("." + rPair.First));
         });
 
         if (it != rDefaults.end())