support O(U)String::number() for fast string concatenation

When I did the fast string concatenation, I didn't add any support
for number(), which simply returned a O(U)String, and so it did
the extra allocation/deallocation, although that could be avoided.
In order to support this, number() now returns a special temporary
return type, similarly to O(U)StringConcat, which allows delaying
the concatenation the same way.
Also similarly, the change of the return type in some cases requires
explicit cast to the actual string type. Usage of OString::getStr()
is so extensive in the codebase that I actually added it to the helper
class, after that it's only relatively few cases.

Change-Id: Iba6e158010e1e458089698c426803052b6f46031
Reviewed-on: https://gerrit.libreoffice.org/78873
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

36 files changed, 483 insertions, 76 deletions

diff --git a/chart2/qa/extras/chart2dump/chart2dump.cxx b/chart2/qa/extras/chart2dump/chart2dump.cxx
index d8b48d3ce3bf..a03f98a0527d 100644
--- a/chart2/qa/extras/chart2dump/chart2dump.cxx
+++ b/chart2/qa/extras/chart2dump/chart2dump.cxx
@@ -50,7 +50,7 @@
     else \
         { \
             OString sTestFileName = OUStringToOString(getTestFileName(), RTL_TEXTENCODING_UTF8); \
-            CPPUNIT_ASSERT_EQUAL_MESSAGE(OString("Failing test file is: " + sTestFileName).getStr(), readExpected(#aActual), OUString::number(aActual)); \
+            CPPUNIT_ASSERT_EQUAL_MESSAGE(OString("Failing test file is: " + sTestFileName).getStr(), readExpected(#aActual), OUString(OUString::number(aActual))); \
         }
 
 #define CPPUNIT_DUMP_ASSERT_DOUBLES_EQUAL(aActual, EPS_) \
diff --git a/compilerplugins/clang/stringconcatauto.cxx b/compilerplugins/clang/stringconcatauto.cxx
index 1437b7537323..7eac4965b3ee 100644
--- a/compilerplugins/clang/stringconcatauto.cxx
+++ b/compilerplugins/clang/stringconcatauto.cxx
@@ -87,6 +87,10 @@ bool StringConcatAuto::checkDecl( const DeclaratorDecl* decl, QualType type, con
         typeString = "OUString";
     else if( tc.Struct("OStringConcat").Namespace("rtl").GlobalNamespace())
         typeString = "OString";
+    else if( tc.Struct("OUStringNumber").Namespace("rtl").GlobalNamespace())
+        typeString = "OUString";
+    else if( tc.Struct("OStringNumber").Namespace("rtl").GlobalNamespace())
+        typeString = "OString";
     else
         return true;
     report( DiagnosticsEngine::Warning,
diff --git a/compilerplugins/clang/test/stringconcatauto.cxx b/compilerplugins/clang/test/stringconcatauto.cxx
index 777da46e84a4..6c9a72c293b3 100644
--- a/compilerplugins/clang/test/stringconcatauto.cxx
+++ b/compilerplugins/clang/test/stringconcatauto.cxx
@@ -23,10 +23,14 @@ void foo()
     const auto str4 = "str4" + OString::number( 40 );
     // expected-error-re@-1 {{creating a variable of type 'const rtl::OStringConcat<{{.*}}>' will make it reference temporaries}}
     // expected-note@-2 {{use OString instead}}
+    auto str5 = OUString::number( 50 );
+    // expected-error-re@-1 {{creating a variable of type 'rtl::OUStringNumber<{{.*}}>' will make it reference temporaries}}
+    // expected-note@-2 {{use OUString instead}}
     (void) str1;
     (void) str2;
     (void) str3;
     (void) str4;
+    (void) str5;
 }
 
 struct A
@@ -37,6 +41,12 @@ struct A
     {
         return "bar" + OString::number( 110 );
     }
+    auto baz()
+    // expected-error-re@-1 {{returning a variable of type 'rtl::OStringNumber<{{.*}}>' will make it reference temporaries}}
+    // expected-note@-2 {{use OString instead}}
+    {
+        return OString::number( 120 );
+    }
 };
 
 template< typename T >
diff --git a/configmgr/source/writemodfile.cxx b/configmgr/source/writemodfile.cxx
index 017e925dee48..d7fba8264b80 100644
--- a/configmgr/source/writemodfile.cxx
+++ b/configmgr/source/writemodfile.cxx
@@ -155,19 +155,19 @@ void writeValueContent_(TempFile &handle, sal_Bool value) {
 }
 
 void writeValueContent_(TempFile &handle, sal_Int16 value) {
-    handle.writeString(OString::number(value));
+    handle.writeString(OString(OString::number(value)));
 }
 
 void writeValueContent_(TempFile &handle, sal_Int32 value) {
-    handle.writeString(OString::number(value));
+    handle.writeString(OString(OString::number(value)));
 }
 
 void writeValueContent_(TempFile &handle, sal_Int64 value) {
-    handle.writeString(OString::number(value));
+    handle.writeString(OString(OString::number(value)));
 }
 
 void writeValueContent_(TempFile &handle, double value) {
-    handle.writeString(OString::number(value));
+    handle.writeString(OString(OString::number(value)));
 }
 
 void writeValueContent_(TempFile &handle, const OUString& value) {
@@ -530,7 +530,7 @@ void writeValueContent(TempFile &handle, std::u16string_view value) {
         {
             handle.writeString(convertToUtf8(value.substr(i, j - i)));
             handle.writeString("<unicode oor:scalar=\"");
-            handle.writeString(OString::number(c));
+            handle.writeString(OString(OString::number(c)));
             handle.writeString("\"/>");
             i = j + 1;
         } else if (c == '\x0D') {
diff --git a/connectivity/source/drivers/file/FStringFunctions.cxx b/connectivity/source/drivers/file/FStringFunctions.cxx
index c8d9977472a6..06e62a1a4cc2 100644
--- a/connectivity/source/drivers/file/FStringFunctions.cxx
+++ b/connectivity/source/drivers/file/FStringFunctions.cxx
@@ -103,7 +103,7 @@ ORowSetValue OOp_Locate::operate(const std::vector<ORowSetValue>& lhs) const
         return ORowSetValue();
 
     if ( lhs.size() == 2 )
-        return OUString::number(lhs[0].getString().indexOf(lhs[1].getString())+1);
+        return OUString(OUString::number(lhs[0].getString().indexOf(lhs[1].getString())+1));
 
     else if ( lhs.size() != 3 )
         return ORowSetValue();
diff --git a/connectivity/source/drivers/flat/ETable.cxx b/connectivity/source/drivers/flat/ETable.cxx
index bc978bcc3599..0e2290dddc91 100644
--- a/connectivity/source/drivers/flat/ETable.cxx
+++ b/connectivity/source/drivers/flat/ETable.cxx
@@ -681,7 +681,7 @@ bool OFlatTable::fetchRow(OValueRefRow& _rRow, const OSQLColumns & _rCols, bool
 
                     // #99178# OJ
                     if ( DataType::DECIMAL == nType || DataType::NUMERIC == nType )
-                        *(_rRow->get())[i] = OUString::number(nVal);
+                        *(_rRow->get())[i] = OUString(OUString::number(nVal));
                     else
                         *(_rRow->get())[i] = nVal;
                 } break;
diff --git a/cui/source/dialogs/cuicharmap.cxx b/cui/source/dialogs/cuicharmap.cxx
index dba595d5dd21..3f0ace55a9b4 100644
--- a/cui/source/dialogs/cuicharmap.cxx
+++ b/cui/source/dialogs/cuicharmap.cxx
@@ -873,7 +873,7 @@ IMPL_LINK(SvxCharacterMap, CharClickHdl, SvxCharView*, rView, void)
     OUString charValue = rView->GetText();
     sal_Int32 tmp = 1;
     sal_UCS4 cChar = charValue.iterateCodePoints(&tmp, -1);
-    OUString aHexText = OUString::number(cChar, 16).toAsciiUpperCase();
+    OUString aHexText = OUString(OUString::number(cChar, 16)).toAsciiUpperCase();
 
     // Get the decimal code
     OUString aDecimalText = OUString::number(cChar);
@@ -961,7 +961,7 @@ IMPL_LINK_NOARG(SvxCharacterMap, CharHighlightHdl, SvxShowCharSet*, void)
         // using the new UCS4 constructor
         aText = OUString( &cChar, 1 );
         // Get the hexadecimal code
-        aHexText = OUString::number(cChar, 16).toAsciiUpperCase();
+        aHexText = OUString(OUString::number(cChar, 16)).toAsciiUpperCase();
         // Get the decimal code
         aDecimalText = OUString::number(cChar);
         setCharName(cChar);
@@ -1001,7 +1001,7 @@ IMPL_LINK_NOARG(SvxCharacterMap, SearchCharHighlightHdl, SvxShowCharSet*, void)
     {
         aText = OUString( &cChar, 1 );
         // Get the hexadecimal code
-        aHexText = OUString::number(cChar, 16).toAsciiUpperCase();
+        aHexText = OUString(OUString::number(cChar, 16)).toAsciiUpperCase();
         // Get the decimal code
         aDecimalText = OUString::number(cChar);
         setCharName(cChar);
diff --git a/desktop/source/lib/init.cxx b/desktop/source/lib/init.cxx
index d26bfaa896cb..400e0e7f82d9 100644
--- a/desktop/source/lib/init.cxx
+++ b/desktop/source/lib/init.cxx
@@ -5162,7 +5162,8 @@ static void lo_status_indicator_callback(void *data, comphelper::LibreOfficeKit:
         pLib->mpCallback(LOK_CALLBACK_STATUS_INDICATOR_START, nullptr, pLib->mpCallbackData);
         break;
     case comphelper::LibreOfficeKit::statusIndicatorCallbackType::SetValue:
-        pLib->mpCallback(LOK_CALLBACK_STATUS_INDICATOR_SET_VALUE, OUString::number(percent).toUtf8().getStr(), pLib->mpCallbackData);
+        pLib->mpCallback(LOK_CALLBACK_STATUS_INDICATOR_SET_VALUE,
+            OUString(OUString::number(percent)).toUtf8().getStr(), pLib->mpCallbackData);
         break;
     case comphelper::LibreOfficeKit::statusIndicatorCallbackType::Finish:
         pLib->mpCallback(LOK_CALLBACK_STATUS_INDICATOR_FINISH, nullptr, pLib->mpCallbackData);
diff --git a/editeng/source/items/numitem.cxx b/editeng/source/items/numitem.cxx
index b9d90c64f764..d83ef10cc3da 100644
--- a/editeng/source/items/numitem.cxx
+++ b/editeng/source/items/numitem.cxx
@@ -701,16 +701,16 @@ void SvxNumRule::Store( SvStream &rStream )
 void SvxNumRule::dumpAsXml(xmlTextWriterPtr pWriter) const
 {
     xmlTextWriterStartElement(pWriter, BAD_CAST("SvxNumRule"));
-    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("levelCount"), BAD_CAST(OUString::number(nLevelCount).getStr()));
-    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("continuousNumbering"), BAD_CAST(OUString::boolean(bContinuousNumbering).getStr()));
-    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("numberingType"), BAD_CAST(OUString::number(static_cast<int>(eNumberingType)).getStr()));
-    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("featureFlags"), BAD_CAST(OUString::number(static_cast<int>(nFeatureFlags)).getStr()));
+    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("levelCount"), BAD_CAST(OString::number(nLevelCount).getStr()));
+    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("continuousNumbering"), BAD_CAST(OString::boolean(bContinuousNumbering).getStr()));
+    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("numberingType"), BAD_CAST(OString::number(static_cast<int>(eNumberingType)).getStr()));
+    xmlTextWriterWriteAttribute(pWriter, BAD_CAST("featureFlags"), BAD_CAST(OString::number(static_cast<int>(nFeatureFlags)).getStr()));
     for(sal_uInt16 i = 0; i < SVX_MAX_NUM; i++)
     {
         if(aFmts[i])
         {
             xmlTextWriterStartElement(pWriter, BAD_CAST("aFmts"));
-            xmlTextWriterWriteAttribute(pWriter, BAD_CAST("i"), BAD_CAST(OUString::number(i).getStr()));
+            xmlTextWriterWriteAttribute(pWriter, BAD_CAST("i"), BAD_CAST(OString::number(i).getStr()));
             xmlTextWriterWriteFormatAttribute(pWriter, BAD_CAST("ptr"), "%p", aFmts[i].get());
             xmlTextWriterEndElement(pWriter);
         }
diff --git a/framework/source/uielement/spinfieldtoolbarcontroller.cxx b/framework/source/uielement/spinfieldtoolbarcontroller.cxx
index 6abf26102e31..3ad582a464ae 100644
--- a/framework/source/uielement/spinfieldtoolbarcontroller.cxx
+++ b/framework/source/uielement/spinfieldtoolbarcontroller.cxx
@@ -299,8 +299,8 @@ void SpinfieldToolbarController::executeControlCommand( const css::frame::Contro
                 double      fValue;
                 bool        bFloat( false );
                 if ( impl_getValue( rControlCommand.Arguments[i].Value, nValue, fValue, bFloat ))
-                    aStep = bFloat ? OUString::number( fValue ) :
-                                     OUString::number( nValue );
+                    aStep = bFloat ? OUString( OUString::number( fValue )) :
+                                     OUString( OUString::number( nValue ));
                 break;
             }
         }
@@ -317,7 +317,8 @@ void SpinfieldToolbarController::executeControlCommand( const css::frame::Contro
 
                 if ( impl_getValue( rControlCommand.Arguments[i].Value, nValue, fValue, bFloat ))
                 {
-                    aValue = bFloat ? OUString::number( fValue ) : OUString::number( nValue );
+                    aValue = bFloat ? OUString( OUString::number( fValue )) :
+                                      OUString( OUString::number( nValue ));
                     bFloatValue = bFloat;
                 }
                 break;
@@ -337,18 +338,19 @@ void SpinfieldToolbarController::executeControlCommand( const css::frame::Contro
             {
                 if ( aName == "Value" )
                 {
-                    aValue = bFloat ? OUString::number( fValue ) : OUString::number( nValue );
+                    aValue = bFloat ? OUString( OUString::number( fValue )) :
+                                      OUString( OUString::number( nValue ));
                     bFloatValue = bFloat;
                 }
                 else if ( aName == "Step" )
-                    aStep = bFloat ? OUString::number( fValue ) :
-                                     OUString::number( nValue );
+                    aStep = bFloat ? OUString( OUString::number( fValue )) :
+                                     OUString( OUString::number( nValue ));
                 else if ( aName == "LowerLimit" )
-                    aMin = bFloat ? OUString::number( fValue ) :
-                                    OUString::number( nValue );
+                    aMin = bFloat ? OUString( OUString::number( fValue )) :
+                                    OUString( OUString::number( nValue ));
                 else if ( aName == "UpperLimit" )
-                    aMax = bFloat ? OUString::number( fValue ) :
-                                    OUString::number( nValue );
+                    aMax = bFloat ? OUString( OUString::number( fValue )) :
+                                    OUString( OUString::number( nValue ));
             }
             else if ( aName == "OutputFormat" )
                 rControlCommand.Arguments[i].Value >>= m_aOutFormat;
@@ -364,8 +366,8 @@ void SpinfieldToolbarController::executeControlCommand( const css::frame::Contro
                 double      fValue;
                 bool        bFloat( false );
                 if ( impl_getValue( rControlCommand.Arguments[i].Value, nValue, fValue, bFloat ))
-                    aMin = bFloat ? OUString::number( fValue ) :
-                                    OUString::number( nValue );
+                    aMin = bFloat ? OUString( OUString::number( fValue )) :
+                                    OUString( OUString::number( nValue ));
                 break;
             }
         }
@@ -380,8 +382,8 @@ void SpinfieldToolbarController::executeControlCommand( const css::frame::Contro
                 double      fValue;
                 bool        bFloat( false );
                 if ( impl_getValue( rControlCommand.Arguments[i].Value, nValue, fValue, bFloat ))
-                    aMax = bFloat ? OUString::number( fValue ) :
-                                    OUString::number( nValue );
+                    aMax = bFloat ? OUString( OUString::number( fValue )) :
+                                    OUString( OUString::number( nValue ));
                 break;
             }
         }
diff --git a/include/com/sun/star/uno/Any.hxx b/include/com/sun/star/uno/Any.hxx
index d7b3420baecc..05f032fc5b81 100644
--- a/include/com/sun/star/uno/Any.hxx
+++ b/include/com/sun/star/uno/Any.hxx
@@ -249,6 +249,14 @@ template<typename T1, typename T2>
 Any toAny(rtl::OUStringConcat<T1, T2> && value)
 { return makeAny(std::move(value)); }
 
+template<typename T>
+Any makeAny(rtl::OUStringNumber<T> && value)
+{ return Any(OUString(std::move(value))); }
+
+template<typename T>
+Any toAny(rtl::OUStringNumber<T> && value)
+{ return makeAny(std::move(value)); }
+
 template<typename T> bool fromAny(Any const & any, T * value) {
     assert(value != nullptr);
     return any >>= *value;
@@ -295,6 +303,17 @@ inline void SAL_CALL operator <<= ( Any & rAny, rtl::OUStringConcat< C1, C2 >&&
 }
 template<typename T1, typename T2>
 void operator <<=(Any &, rtl::OUStringConcat<T1, T2> const &) = delete;
+template< class C >
+inline void SAL_CALL operator <<= ( Any & rAny, rtl::OUStringNumber< C >&& value )
+{
+    const rtl::OUString str( std::move(value) );
+    const Type & rType = ::cppu::getTypeFavourUnsigned(&str);
+    ::uno_type_any_assign(
+        &rAny, const_cast< rtl::OUString * >( &str ), rType.getTypeLibType(),
+        cpp_acquire, cpp_release );
+}
+template<typename T>
+void operator <<=(Any &, rtl::OUStringNumber<T> const &) = delete;
 #endif
 
 #if defined LIBO_INTERNAL_ONLY
diff --git a/include/rtl/strbuf.hxx b/include/rtl/strbuf.hxx
index 2b8e6506b6b6..832c48959d47 100644
--- a/include/rtl/strbuf.hxx
+++ b/include/rtl/strbuf.hxx
@@ -222,6 +222,15 @@ public:
         *end = '\0';
         pData->length = l;
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OStringBuffer( OStringNumber< T >&& n )
+        : OStringBuffer( OString( n ))
+    {}
 #endif
 
     /** Assign to this a copy of value.
@@ -287,6 +296,13 @@ public:
         pData->length = n;
         return *this;
     }
+
+    /** @overload @internal */
+    template<typename T>
+    OStringBuffer & operator =(OStringNumber<T> && n)
+    {
+        return *this = OStringBuffer( std::move ( n ));
+    }
 #endif
 
     /**
@@ -560,6 +576,17 @@ public:
         pData->length = l;
         return *this;
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OStringBuffer& append( OStringNumber< T >&& c )
+    {
+        return append( c.buf, c.length );
+    }
+
 #endif
 
     /**
diff --git a/include/rtl/string.hxx b/include/rtl/string.hxx
index d06a1b727394..68450da21fa9 100644
--- a/include/rtl/string.hxx
+++ b/include/rtl/string.hxx
@@ -280,6 +280,15 @@ public:
             *end = '\0';
         }
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OString( OStringNumber< T >&& n )
+        : OString( n.buf, n.length )
+    {}
 #endif
 
 #ifdef LIBO_INTERNAL_ONLY
@@ -383,6 +392,25 @@ public:
     }
     template<typename T1, typename T2> void operator +=(
         OStringConcat<T1, T2> &&) && = delete;
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OString& operator+=( OStringNumber< T >&& n ) & {
+        sal_Int32 l = n.length;
+        if( l == 0 )
+            return *this;
+        l += pData->length;
+        rtl_string_ensureCapacity( &pData, l );
+        char* end = addDataHelper( pData->buffer + pData->length, n.buf, n.length );
+        *end = '\0';
+        pData->length = l;
+        return *this;
+    }
+    template<typename T> void operator +=(
+        OStringNumber<T> &&) && = delete;
 #endif
 
     /**
@@ -1602,6 +1630,41 @@ public:
         return rtl_str_toDouble( pData->buffer );
     }
 
+#ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+
+    static OStringNumber< int > number( int i, sal_Int16 radix = 10 )
+    {
+        return OStringNumber< int >( i, radix );
+    }
+    static OStringNumber< long long > number( long long ll, sal_Int16 radix = 10 )
+    {
+        return OStringNumber< long long >( ll, radix );
+    }
+    static OStringNumber< unsigned long long > number( unsigned long long ll, sal_Int16 radix = 10 )
+    {
+        return OStringNumber< unsigned long long >( ll, radix );
+    }
+    static OStringNumber< unsigned long long > number( unsigned int i, sal_Int16 radix = 10 )
+    {
+        return number( static_cast< unsigned long long >( i ), radix );
+    }
+    static OStringNumber< long long > number( long i, sal_Int16 radix = 10)
+    {
+        return number( static_cast< long long >( i ), radix );
+    }
+    static OStringNumber< unsigned long long > number( unsigned long i, sal_Int16 radix = 10 )
+    {
+        return number( static_cast< unsigned long long >( i ), radix );
+    }
+    static OStringNumber< float > number( float f )
+    {
+        return OStringNumber< float >( f );
+    }
+    static OStringNumber< double > number( double d )
+    {
+        return OStringNumber< double >( d );
+    }
+#else
     /**
       Returns the string representation of the integer argument.
 
@@ -1686,6 +1749,7 @@ public:
         rtl_string_newFromStr_WithLength( &pNewData, aBuf, rtl_str_valueOfDouble( aBuf, d ) );
         return OString( pNewData, SAL_NO_ACQUIRE );
     }
+#endif
 
     /**
       Returns the string representation of the sal_Bool argument.
diff --git a/include/rtl/stringconcat.hxx b/include/rtl/stringconcat.hxx
index 220d0a2cfc9e..50522636ea3d 100644
--- a/include/rtl/stringconcat.hxx
+++ b/include/rtl/stringconcat.hxx
@@ -11,6 +11,8 @@
 #define INCLUDED_RTL_STRINGCONCAT_HXX
 
 #include "rtl/stringutils.hxx"
+#include "rtl/string.h"
+#include "rtl/ustring.h"
 
 #include <cstddef>
 #include <string.h>
@@ -168,6 +170,9 @@ template<> struct ToStringHelper<OUStringLiteral1_> {
 
 Objects returned by operator+, instead of OString. These objects (possibly recursively) keep a representation of the whole
 concatenation operation.
+
+If you get a build error related to this class, you most probably need to explicitly convert the result of a string
+concatenation to OString.
 */
 template< typename T1, typename T2 >
 struct OStringConcat
@@ -189,6 +194,9 @@ struct OStringConcat
 
 Objects returned by operator+, instead of OUString. These objects (possibly recursively) keep a representation of the whole
 concatenation operation.
+
+If you get a build error related to this class, you most probably need to explicitly convert the result of a string
+concatenation to OUString.
 */
 template< typename T1, typename T2 >
 struct OUStringConcat
@@ -302,6 +310,156 @@ int operator+( const StringConcatInvalid&, const T& )
     }
 #endif
 
+/**
+ @internal
+
+Objects returned by OString::number(), instead of OString. These objects keep a representation of the number() operation.
+
+If you get a build error related to this class, you most probably need to explicitly convert the result of calling
+OString::number() to OString.
+*/
+template< typename T >
+struct OStringNumber;
+
+template<>
+struct OStringNumber< int >
+{
+    OStringNumber( int i, sal_Int16 radix )
+        : length( rtl_str_valueOfInt32( buf, i, radix ))
+    {}
+    // OString::number(value).getStr() is very common (writing xml code, ...),
+    // so implement that one also here, to avoid having to explicitly to convert
+    // to OString in all such places
+    const char * getStr() const SAL_RETURNS_NONNULL { return buf; }
+    char buf[RTL_STR_MAX_VALUEOFINT32];
+    const sal_Int32 length;
+};
+
+template<>
+struct OStringNumber< long long >
+{
+    OStringNumber( long long ll, sal_Int16 radix )
+        : length( rtl_str_valueOfInt64( buf, ll, radix ))
+    {}
+    const char * getStr() const SAL_RETURNS_NONNULL { return buf; }
+    char buf[RTL_STR_MAX_VALUEOFINT64];
+    const sal_Int32 length;
+};
+
+template<>
+struct OStringNumber< unsigned long long >
+{
+    OStringNumber( unsigned long long ll, sal_Int16 radix )
+        : length( rtl_str_valueOfUInt64( buf, ll, radix ))
+    {}
+    const char * getStr() const SAL_RETURNS_NONNULL { return buf; }
+    char buf[RTL_STR_MAX_VALUEOFUINT64];
+    const sal_Int32 length;
+};
+
+template<>
+struct OStringNumber< float >
+{
+    OStringNumber( float f )
+        : length( rtl_str_valueOfFloat( buf, f ))
+    {}
+    const char * getStr() const SAL_RETURNS_NONNULL { return buf; }
+    char buf[RTL_STR_MAX_VALUEOFFLOAT];
+    const sal_Int32 length;
+};
+
+template<>
+struct OStringNumber< double >
+{
+    OStringNumber( double d )
+        : length( rtl_str_valueOfDouble( buf, d ))
+    {}
+    const char * getStr() const SAL_RETURNS_NONNULL { return buf; }
+    char buf[RTL_STR_MAX_VALUEOFDOUBLE];
+    const sal_Int32 length;
+};
+
+template< typename T >
+struct ToStringHelper< OStringNumber< T > >
+    {
+    static int length( const OStringNumber< T >& n ) { return n.length; }
+    static char* addData( char* buffer, const OStringNumber< T >& n ) SAL_RETURNS_NONNULL { return addDataHelper( buffer, n.buf, n.length ); }
+    static const bool allowOStringConcat = true;
+    static const bool allowOUStringConcat = false;
+    };
+
+
+/**
+ @internal
+
+Objects returned by OUString::number(), instead of OUString. These objects keep a representation of the number() operation.
+
+If you get a build error related to this class, you most probably need to explicitly convert the result of calling
+OUString::number() to OUString.
+*/
+template< typename T >
+struct OUStringNumber;
+
+template<>
+struct OUStringNumber< int >
+{
+    OUStringNumber( int i, sal_Int16 radix )
+        : length( rtl_ustr_valueOfInt32( buf, i, radix ))
+    {}
+    sal_Unicode buf[RTL_USTR_MAX_VALUEOFINT32];
+    const sal_Int32 length;
+};
+
+template<>
+struct OUStringNumber< long long >
+{
+    OUStringNumber( long long ll, sal_Int16 radix )
+        : length( rtl_ustr_valueOfInt64( buf, ll, radix ))
+    {}
+    sal_Unicode buf[RTL_USTR_MAX_VALUEOFINT64];
+    const sal_Int32 length;
+};
+
+template<>
+struct OUStringNumber< unsigned long long >
+{
+    OUStringNumber( unsigned long long ll, sal_Int16 radix )
+        : length( rtl_ustr_valueOfUInt64( buf, ll, radix ))
+    {}
+    sal_Unicode buf[RTL_USTR_MAX_VALUEOFUINT64];
+    const sal_Int32 length;
+};
+
+template<>
+struct OUStringNumber< float >
+{
+    OUStringNumber( float f )
+        : length( rtl_ustr_valueOfFloat( buf, f ))
+    {}
+    sal_Unicode buf[RTL_USTR_MAX_VALUEOFFLOAT];
+    const sal_Int32 length;
+};
+
+template<>
+struct OUStringNumber< double >
+{
+    OUStringNumber( double d )
+        : length( rtl_ustr_valueOfDouble( buf, d ))
+    {}
+    sal_Unicode buf[RTL_USTR_MAX_VALUEOFDOUBLE];
+    const sal_Int32 length;
+};
+
+template< typename T >
+struct ToStringHelper< OUStringNumber< T > >
+    {
+    static int length( const OUStringNumber< T >& n ) { return n.length; }
+    static sal_Unicode* addData( sal_Unicode* buffer, const OUStringNumber< T >& n ) SAL_RETURNS_NONNULL { return addDataHelper( buffer, n.buf, n.length ); }
+    static const bool allowOStringConcat = false;
+    static const bool allowOUStringConcat = true;
+    };
+
+
 } // namespace
 
 #endif
diff --git a/include/rtl/ustrbuf.hxx b/include/rtl/ustrbuf.hxx
index 94bf9c789a61..4016eaf210d9 100644
--- a/include/rtl/ustrbuf.hxx
+++ b/include/rtl/ustrbuf.hxx
@@ -224,6 +224,18 @@ public:
         pData->length = l;
         // TODO realloc in case pData->>length is noticeably smaller than l ?
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OUStringBuffer( OUStringNumber< T >&& n )
+        : pData(NULL)
+        , nCapacity( n.length + 16 )
+    {
+        rtl_uStringbuffer_newFromStr_WithLength( &pData, n.buf, n.length );
+    }
 #endif
     /** Assign to this a copy of value.
      */
@@ -328,6 +340,13 @@ public:
         pData->length = n;
         return *this;
     }
+
+    /** @overload @internal */
+    template<typename T>
+    OUStringBuffer & operator =(OUStringNumber<T> && n)
+    {
+        return *this = OUStringBuffer( std::move( n ));
+    }
 #endif
 
     /**
@@ -658,6 +677,16 @@ public:
         pData->length = l;
         return *this;
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OUStringBuffer& append( OUStringNumber< T >&& c )
+    {
+        return append( c.buf, c.length );
+    }
 #endif
 
     /**
diff --git a/include/rtl/ustring.h b/include/rtl/ustring.h
index 90aff10dd169..35e4a7d4ad67 100644
--- a/include/rtl/ustring.h
+++ b/include/rtl/ustring.h
@@ -1000,7 +1000,7 @@ SAL_DLLPUBLIC sal_Int32 SAL_CALL rtl_ustr_valueOfInt64(
  */
 SAL_DLLPUBLIC sal_Int32 SAL_CALL rtl_ustr_valueOfUInt64(
         sal_Unicode * str, sal_uInt64 l, sal_Int16 radix ) SAL_THROW_EXTERN_C();
-#define RTL_USTR_MAX_VALUEOFINT64 RTL_STR_MAX_VALUEOFINT64
+#define RTL_USTR_MAX_VALUEOFUINT64 RTL_STR_MAX_VALUEOFUINT64
 
 /** Create the string representation of a float.
 
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index 18b717fd2b04..a6d9e22c37b5 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -409,6 +409,15 @@ public:
             // TODO realloc in case pData->length is noticeably smaller than l?
         }
     }
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OUString( OUStringNumber< T >&& n )
+        : OUString( n.buf, n.length )
+    {}
 #endif
 
 #if defined LIBO_INTERNAL_ONLY
@@ -632,6 +641,25 @@ public:
     }
     template<typename T1, typename T2> void operator +=(
         OUStringConcat<T1, T2> &&) && = delete;
+
+    /**
+     @overload
+     @internal
+    */
+    template< typename T >
+    OUString& operator+=( OUStringNumber< T >&& n ) & {
+        sal_Int32 l = n.length;
+        if( l == 0 )
+            return *this;
+        l += pData->length;
+        rtl_uString_ensureCapacity( &pData, l );
+        sal_Unicode* end = addDataHelper( pData->buffer + pData->length, n.buf, n.length );
+        *end = '\0';
+        pData->length = l;
+        return *this;
+    }
+    template<typename T> void operator +=(
+        OUStringNumber<T> &&) && = delete;
 #endif
 
     /**
@@ -3345,6 +3373,41 @@ public:
         return aTarget;
     }
 
+#ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+
+    static OUStringNumber< int > number( int i, sal_Int16 radix = 10 )
+    {
+        return OUStringNumber< int >( i, radix );
+    }
+    static OUStringNumber< long long > number( long long ll, sal_Int16 radix = 10 )
+    {
+        return OUStringNumber< long long >( ll, radix );
+    }
+    static OUStringNumber< unsigned long long > number( unsigned long long ll, sal_Int16 radix = 10 )
+    {
+        return OUStringNumber< unsigned long long >( ll, radix );
+    }
+    static OUStringNumber< unsigned long long > number( unsigned int i, sal_Int16 radix = 10 )
+    {
+        return number( static_cast< unsigned long long >( i ), radix );
+    }
+    static OUStringNumber< long long > number( long i, sal_Int16 radix = 10)
+    {
+        return number( static_cast< long long >( i ), radix );
+    }
+    static OUStringNumber< unsigned long long > number( unsigned long i, sal_Int16 radix = 10 )
+    {
+        return number( static_cast< unsigned long long >( i ), radix );
+    }
+    static OUStringNumber< float > number( float f )
+    {
+        return OUStringNumber< float >( f );
+    }
+    static OUStringNumber< double > number( double d )
+    {
+        return OUStringNumber< double >( d );
+    }
+#else
     /**
       Returns the string representation of the integer argument.
 
@@ -3432,6 +3495,7 @@ public:
         rtl_uString_newFromStr_WithLength( &pNewData, aBuf, rtl_ustr_valueOfDouble( aBuf, d ) );
         return OUString( pNewData, SAL_NO_ACQUIRE );
     }
+#endif
 
     /**
       Returns the string representation of the sal_Bool argument.
diff --git a/oox/source/export/chartexport.cxx b/oox/source/export/chartexport.cxx
index c282b0d9263f..3b0072838a87 100644
--- a/oox/source/export/chartexport.cxx
+++ b/oox/source/export/chartexport.cxx
@@ -3137,7 +3137,7 @@ void writeLabelProperties( const FSHelperPtr& pFS, ChartExport* pChartExport,
         {
             pFS->startElement(FSNS(XML_a, XML_solidFill));
 
-            OString aStr = OString::number(nLabelBorderColor, 16).toAsciiUpperCase();
+            OString aStr = OString(OString::number(nLabelBorderColor, 16)).toAsciiUpperCase();
             pFS->singleElement(FSNS(XML_a, XML_srgbClr), XML_val, aStr);
 
             pFS->endElement(FSNS(XML_a, XML_solidFill));
diff --git a/sal/qa/rtl/oustring/rtl_OUString2.cxx b/sal/qa/rtl/oustring/rtl_OUString2.cxx
index 3b6474d1cafa..52e8656efd96 100644
--- a/sal/qa/rtl/oustring/rtl_OUString2.cxx
+++ b/sal/qa/rtl/oustring/rtl_OUString2.cxx
@@ -896,11 +896,11 @@ public:
         std::unique_ptr<OUString[]> pStrs(new OUString[nSequence]);
         for (i = 0; i < nSequence; i++)
         {
-            pStrs[i] = OUString::number( sqrt( static_cast<double>(i) ) ).intern();
+            pStrs[i] = OUString( OUString::number( sqrt( static_cast<double>(i) ) ) ).intern();
         }
         for (i = 0; i < nSequence; i++)
         {
-            OUString aNew = OUString::number( sqrt( static_cast<double>(i) ) ).intern();
+            OUString aNew = OUString( OUString::number( sqrt( static_cast<double>(i) ) ) ).intern();
             CPPUNIT_ASSERT_EQUAL_MESSAGE("double intern failed",
                                    pStrs[i].pData, aNew.pData);
         }
diff --git a/sal/qa/rtl/strings/test_ostring_concat.cxx b/sal/qa/rtl/strings/test_ostring_concat.cxx
index 15795d039cee..e676aab2d27e 100644
--- a/sal/qa/rtl/strings/test_ostring_concat.cxx
+++ b/sal/qa/rtl/strings/test_ostring_concat.cxx
@@ -81,6 +81,19 @@ void test::ostring::StringConcat::checkConcat()
     CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, const char* > )), typeid( OString( "foo" ) + d3 ));
     CPPUNIT_ASSERT_EQUAL( OString( "fooabc" ), OString( OString( "foo" ) + d4 ));
     CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, char* > )), typeid( OString( "foo" ) + d4 ));
+    CPPUNIT_ASSERT_EQUAL( OString( "fooabc" ), OString( OString( "foo" ) + d4 ));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, char* > )), typeid( OString( "foo" ) + d4 ));
+
+    CPPUNIT_ASSERT_EQUAL( OString( "num10" ), OString( OString( "num" ) + OString::number( 10 )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, OStringNumber< int > > )), typeid( OString( "num" ) + OString::number( 10 )));
+    CPPUNIT_ASSERT_EQUAL( OString( "num10" ), OString( OString( "num" ) + OString::number( 10L )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, OStringNumber< long long > > )), typeid( OString( "num" ) + OString::number( 10L )));
+    CPPUNIT_ASSERT_EQUAL( OString( "num10" ), OString( OString( "num" ) + OString::number( 10ULL )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, OStringNumber< unsigned long long > > )), typeid( OString( "num" ) + OString::number( 10ULL )));
+    CPPUNIT_ASSERT_EQUAL( OString( "num10.5" ), OString( OString( "num" ) + OString::number( 10.5f )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, OStringNumber< float > > )), typeid( OString( "num" ) + OString::number( 10.5f )));
+    CPPUNIT_ASSERT_EQUAL( OString( "num10.5" ), OString( OString( "num" ) + OString::number( 10.5 )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OStringConcat< OString, OStringNumber< double > > )), typeid( OString( "num" ) + OString::number( 10.5 )));
 }
 
 void test::ostring::StringConcat::checkEnsureCapacity()
@@ -149,6 +162,8 @@ void test::ostring::StringConcat::checkInvalid()
     rtl_uString* rus = nullptr;
     CPPUNIT_ASSERT( INVALID_CONCAT( OUString( "b" ) + rs ));
     CPPUNIT_ASSERT( INVALID_CONCAT( OUString( "b" ) + rus ));
+    CPPUNIT_ASSERT( INVALID_CONCAT( OString( "a" ) + OUString::number( 10 )));
+    CPPUNIT_ASSERT( INVALID_CONCAT( OString::number( 0 ) + OUString::number( 10 )));
 
 #if 0
     // Should fail to compile, to avoid use of OStringConcat lvalues that
diff --git a/sal/qa/rtl/strings/test_oustring_concat.cxx b/sal/qa/rtl/strings/test_oustring_concat.cxx
index 8ec1699d4431..56b38ec1ee90 100644
--- a/sal/qa/rtl/strings/test_oustring_concat.cxx
+++ b/sal/qa/rtl/strings/test_oustring_concat.cxx
@@ -71,6 +71,17 @@ void test::oustring::StringConcat::checkConcat()
     const char d1[] = "xyz";
     CPPUNIT_ASSERT_EQUAL( OUString( "fooxyz" ), OUString( OUString( "foo" ) + d1 ));
     CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, const char[ 4 ] > )), typeid( OUString( "foo" ) + d1 ));
+
+    CPPUNIT_ASSERT_EQUAL( OUString( "num10" ), OUString( OUString( "num" ) + OUString::number( 10 )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, OUStringNumber< int > > )), typeid( OUString( "num" ) + OUString::number( 10 )));
+    CPPUNIT_ASSERT_EQUAL( OUString( "num10" ), OUString( OUString( "num" ) + OUString::number( 10L )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, OUStringNumber< long long > > )), typeid( OUString( "num" ) + OUString::number( 10L )));
+    CPPUNIT_ASSERT_EQUAL( OUString( "num10" ), OUString( OUString( "num" ) + OUString::number( 10ULL )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, OUStringNumber< unsigned long long > > )), typeid( OUString( "num" ) + OUString::number( 10ULL )));
+    CPPUNIT_ASSERT_EQUAL( OUString( "num10.5" ), OUString( OUString( "num" ) + OUString::number( 10.5f )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, OUStringNumber< float > > )), typeid( OUString( "num" ) + OUString::number( 10.5f )));
+    CPPUNIT_ASSERT_EQUAL( OUString( "num10.5" ), OUString( OUString( "num" ) + OUString::number( 10.5 )));
+    CPPUNIT_ASSERT_EQUAL(( typeid( OUStringConcat< OUString, OUStringNumber< double > > )), typeid( OUString( "num" ) + OUString::number( 10.5 )));
 }
 
 void test::oustring::StringConcat::checkConcatAsciiL()
@@ -159,6 +170,8 @@ void test::oustring::StringConcat::checkInvalid()
     rtl_uString* rus = nullptr;
     CPPUNIT_ASSERT( INVALID_CONCAT( OUString( "b" ) + rs ));
     CPPUNIT_ASSERT( INVALID_CONCAT( OUString( "b" ) + rus ));
+    CPPUNIT_ASSERT( INVALID_CONCAT( OUString( "a" ) + OString::number( 10 )));
+    CPPUNIT_ASSERT( INVALID_CONCAT( OUString::number( 0 ) + OString::number( 10 )));
 
 #if 0
     // Should fail to compile, to avoid use of OUStringConcat lvalues that
diff --git a/sal/qa/rtl/strings/test_strings_valuex.cxx b/sal/qa/rtl/strings/test_strings_valuex.cxx
index b1102cce6fd1..85fee5f00dd8 100644
--- a/sal/qa/rtl/strings/test_strings_valuex.cxx
+++ b/sal/qa/rtl/strings/test_strings_valuex.cxx
@@ -58,30 +58,30 @@ void test::strings::valueX::testOUBoolean() {
 
 template< typename T >
 static void testInt() {
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( 30039062 ));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( 30039062 )));
 
     // test the overloading resolution
 
-    CPPUNIT_ASSERT_EQUAL( T( "30" ), T::number( static_cast< signed char >( 30 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30" ), T::number( static_cast< unsigned char >( 30 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T::number( static_cast< short >( 30039 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T::number( static_cast< unsigned short >( 30039 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< int >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< unsigned int >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< long >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< unsigned long >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< long long >( 30039062 )));
+    CPPUNIT_ASSERT_EQUAL( T( "30" ), T( T::number( static_cast< signed char >( 30 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30" ), T( T::number( static_cast< unsigned char >( 30 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T( T::number( static_cast< short >( 30039 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T( T::number( static_cast< unsigned short >( 30039 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< int >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< unsigned int >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< long >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< unsigned long >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< long long >( 30039062 ))));
     // The highest bit set in unsigned long long may not actually work.
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< unsigned long long >( 30039062 )));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< unsigned long long >( 30039062 ))));
 
-    CPPUNIT_ASSERT_EQUAL( T( "30" ), T::number( static_cast< sal_Int8 >( 30 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30" ), T::number( static_cast< sal_uInt8 >( 30 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T::number( static_cast< sal_Int16 >( 30039 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T::number( static_cast< sal_uInt16 >( 30039 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< sal_Int32 >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< sal_uInt32 >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< sal_Int64 >( 30039062 )));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T::number( static_cast< sal_uInt64 >( 30039062 )));
+    CPPUNIT_ASSERT_EQUAL( T( "30" ), T( T::number( static_cast< sal_Int8 >( 30 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30" ), T( T::number( static_cast< sal_uInt8 >( 30 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T( T::number( static_cast< sal_Int16 >( 30039 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039" ), T( T::number( static_cast< sal_uInt16 >( 30039 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< sal_Int32 >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< sal_uInt32 >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< sal_Int64 >( 30039062 ))));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062" ), T( T::number( static_cast< sal_uInt64 >( 30039062 ))));
 
     // The implementation internally uses sal_Int64 etc. types, so check ranges.
     assert( sizeof( int ) <= sizeof( sal_Int32 ));
@@ -100,8 +100,8 @@ void test::strings::valueX::testOInt() {
 
 template< typename T >
 static void testFloat() {
-    CPPUNIT_ASSERT_EQUAL( T( "39062.2" ), T::number( 39062.2f ));
-    CPPUNIT_ASSERT_EQUAL( T( "30039062.2" ), T::number( 30039062.2 ));
+    CPPUNIT_ASSERT_EQUAL( T( "39062.2" ), T( T::number( 39062.2f )));
+    CPPUNIT_ASSERT_EQUAL( T( "30039062.2" ), T( T::number( 30039062.2 )));
     // long double not supported
 }
 
diff --git a/sc/source/core/tool/interpr7.cxx b/sc/source/core/tool/interpr7.cxx
index 908c1d20aef2..4e682b531df8 100644
--- a/sc/source/core/tool/interpr7.cxx
+++ b/sc/source/core/tool/interpr7.cxx
@@ -437,7 +437,7 @@ void ScInterpreter::ScEncodeURL()
             else
             {
                 aUrlBuf.append( '%' );
-                OString convertedChar = OString::number( static_cast<unsigned char>( c ), 16 ).toAsciiUpperCase();
+                OString convertedChar = OString( OString::number( static_cast<unsigned char>( c ), 16 )).toAsciiUpperCase();
                 // RFC 3986 indicates:
                 // "A percent-encoded octet is encoded as a character triplet,
                 // consisting of the percent character "%" followed by the two hexadecimal digits
diff --git a/sc/source/filter/excel/xepage.cxx b/sc/source/filter/excel/xepage.cxx
index 3e32ab1f3251..9783ea5e5fc0 100644
--- a/sc/source/filter/excel/xepage.cxx
+++ b/sc/source/filter/excel/xepage.cxx
@@ -95,8 +95,8 @@ void XclExpSetup::SaveXml( XclExpXmlStream& rStrm )
     }
     else
     {
-        pAttrList->add( XML_paperWidth,          OString::number(  mrData.mnPaperWidth ).concat("mm").getStr() );
-        pAttrList->add( XML_paperHeight,         OString::number(  mrData.mnPaperHeight ).concat("mm").getStr() );
+        pAttrList->add( XML_paperWidth,     OString(OString::number( mrData.mnPaperWidth ) + "mm").getStr() );
+        pAttrList->add( XML_paperHeight,    OString(OString::number( mrData.mnPaperHeight ) + "mm").getStr() );
         // pAttrList->add( XML_paperUnits,          "mm" );
     }
     pAttrList->add( XML_scale,              OString::number(  mrData.mnScaling ).getStr() );
diff --git a/sc/source/filter/inc/xestream.hxx b/sc/source/filter/inc/xestream.hxx
index 93b070a55da9..6b8152bc6b48 100644
--- a/sc/source/filter/inc/xestream.hxx
+++ b/sc/source/filter/inc/xestream.hxx
@@ -287,12 +287,12 @@ public:
     sax_fastparser::FSHelperPtr     GetStreamForPath( const OUString& rPath );
 
     template <typename Str, typename... Args>
-    void WriteAttributes(sal_Int32 nAttribute, const Str& value, Args... rest)
+    void WriteAttributes(sal_Int32 nAttribute, Str&& value, Args&&... rest)
     {
-        WriteAttribute(nAttribute, value);
+        WriteAttribute(nAttribute, std::forward<Str>(value));
         // coverity[stray_semicolon : FALSE] - coverity parse error
         if constexpr(sizeof...(rest) > 0)
-            WriteAttributes(rest...);
+            WriteAttributes(std::forward<Args>(rest)...);
     }
 
     sax_fastparser::FSHelperPtr     CreateOutputStream (
diff --git a/scaddins/source/analysis/analysishelper.cxx b/scaddins/source/analysis/analysishelper.cxx
index 502e47a5d252..ae83afd174fb 100644
--- a/scaddins/source/analysis/analysishelper.cxx
+++ b/scaddins/source/analysis/analysishelper.cxx
@@ -709,7 +709,7 @@ OUString ConvertFromDec( double fNum, double fMin, double fMax, sal_uInt16 nBase
     if( bNeg )
         nNum = sal_Int64( pow( double( nBase ), double( nMaxPlaces ) ) ) + nNum;
 
-    OUString          aRet( OUString::number( nNum, nBase ).toAsciiUpperCase() );
+    OUString          aRet( OUString( OUString::number( nNum, nBase )).toAsciiUpperCase() );
 
 
     if( bUsePlaces )
diff --git a/sd/source/ui/unoidl/unomodel.cxx b/sd/source/ui/unoidl/unomodel.cxx
index cf31dfa902e7..eeda330cc569 100644
--- a/sd/source/ui/unoidl/unomodel.cxx
+++ b/sd/source/ui/unoidl/unomodel.cxx
@@ -2405,7 +2405,7 @@ OUString SdXImpressDocument::getPostIts()
             aAnnotation.put("dateTime", utl::toISO8601(xAnnotation->getDateTime()));
             uno::Reference<text::XText> xText(xAnnotation->getTextRange());
             aAnnotation.put("text", xText->getString());
-            aAnnotation.put("parthash", OUString::number(pPage->GetHashCode()));
+            aAnnotation.put("parthash", OUString(OUString::number(pPage->GetHashCode())));
 
             aAnnotations.push_back(std::make_pair("", aAnnotation));
         }
diff --git a/sfx2/source/appl/fileobj.cxx b/sfx2/source/appl/fileobj.cxx
index 2c42c5a59e33..744793e0626e 100644
--- a/sfx2/source/appl/fileobj.cxx
+++ b/sfx2/source/appl/fileobj.cxx
@@ -430,7 +430,7 @@ void SvFileObject::SendStateChg_Impl( sfx2::LinkManager::LinkState nState )
     if( !bStateChangeCalled && HasDataLinks() )
     {
         DataChanged( SotExchange::GetFormatName(
-                        sfx2::LinkManager::RegisterStatusInfoId()), css::uno::Any(OUString::number( nState )) );
+                        sfx2::LinkManager::RegisterStatusInfoId()), css::uno::makeAny(OUString::number( nState )) );
         bStateChangeCalled = true;
     }
 }
diff --git a/starmath/source/dialog.cxx b/starmath/source/dialog.cxx
index 066c4016c07a..5e236f6460d3 100644
--- a/starmath/source/dialog.cxx
+++ b/starmath/source/dialog.cxx
@@ -1584,7 +1584,7 @@ IMPL_LINK_NOARG(SmSymDefineDialog, CharHighlightHdl, SvxShowCharSet*, void)
     UpdateButtons();
 
     // display Unicode position as symbol name while iterating over characters
-    const OUString aHex(OUString::number(cChar, 16 ).toAsciiUpperCase());
+    const OUString aHex(OUString(OUString::number(cChar, 16 )).toAsciiUpperCase());
     const OUString aPattern( (aHex.getLength() > 4) ? OUString("Ux000000") : OUString("Ux0000") );
     OUString aUnicodePos( aPattern.copy( 0, aPattern.getLength() - aHex.getLength() ) );
     aUnicodePos += aHex;
diff --git a/svl/source/numbers/zforlist.cxx b/svl/source/numbers/zforlist.cxx
index 7a558bd015df..04fcc99a9772 100644
--- a/svl/source/numbers/zforlist.cxx
+++ b/svl/source/numbers/zforlist.cxx
@@ -4210,7 +4210,7 @@ OUString NfCurrencyEntry::BuildSymbolString(bool bBank,
         if ( !bWithoutExtension && eLanguage != LANGUAGE_DONTKNOW && eLanguage != LANGUAGE_SYSTEM )
         {
             sal_Int32 nLang = static_cast<sal_uInt16>(eLanguage);
-            aBuf.append('-').append( OUString::number(nLang, 16).toAsciiUpperCase());
+            aBuf.append('-').append( OUString( OUString::number(nLang, 16)).toAsciiUpperCase());
         }
     }
     aBuf.append(']');
diff --git a/svl/source/numbers/zformat.cxx b/svl/source/numbers/zformat.cxx
index 092d6b2b5908..64505adab290 100644
--- a/svl/source/numbers/zformat.cxx
+++ b/svl/source/numbers/zformat.cxx
@@ -1165,7 +1165,7 @@ SvNumberformat::SvNumberformat(OUString& rString,
                             ((eLanguage = MsLangId::getRealLanguage( eLan)) == LANGUAGE_THAI) &&
                             NumFor[nIndex].GetNatNum().GetLang() == LANGUAGE_DONTKNOW)
                         {
-                            sStr = "[$-" + OUString::number( sal_uInt16(eLanguage), 16 ).toAsciiUpperCase() + "]" + sStr;
+                            sStr = "[$-" + OUString(OUString::number( sal_uInt16(eLanguage), 16 )).toAsciiUpperCase() + "]" + sStr;
                             NumFor[nIndex].SetNatNumLang( eLanguage);
                         }
                         sBuff.remove(nPosOld, nPos - nPosOld);
@@ -5085,7 +5085,7 @@ static void lcl_insertLCID( OUStringBuffer& rFormatStr, sal_uInt32 nLCID, sal_In
         // No format code, no locale.
         return;
 
-    OUStringBuffer aLCIDString = OUString::number( nLCID , 16 ).toAsciiUpperCase();
+    OUStringBuffer aLCIDString = OUString(OUString::number( nLCID , 16 )).toAsciiUpperCase();
     // Search for only last DBNum which is the last element before insertion position
     if ( bDBNumInserted && nPosInsertLCID >= 8
         && aLCIDString.getLength() > 4
diff --git a/tools/qa/cppunit/test_xmlwalker.cxx b/tools/qa/cppunit/test_xmlwalker.cxx
index 4c2f9a808ea6..e06886deddd8 100644
--- a/tools/qa/cppunit/test_xmlwalker.cxx
+++ b/tools/qa/cppunit/test_xmlwalker.cxx
@@ -53,7 +53,8 @@ void XmlWalkerTest::testReadXML()
         {
             nNumberOfChildNodes++;
 
-            CPPUNIT_ASSERT_EQUAL(OString::number(nNumberOfChildNodes), aWalker.attribute("number"));
+            CPPUNIT_ASSERT_EQUAL(OString(OString::number(nNumberOfChildNodes)),
+                                 aWalker.attribute("number"));
 
             if (nNumberOfChildNodes == 1) // only the first node has the attribute
                 CPPUNIT_ASSERT_EQUAL(OString("123"), aWalker.attribute("attribute"));
diff --git a/unoidl/source/sourceprovider-scanner.l b/unoidl/source/sourceprovider-scanner.l
index 29d594caf8e5..d0dd5a0dc155 100644
--- a/unoidl/source/sourceprovider-scanner.l
+++ b/unoidl/source/sourceprovider-scanner.l
@@ -245,7 +245,7 @@ ALNUM {DIGIT}|{ALPHA}
     yyextra->errorMessage = c >= ' ' && c <= '~'
         ? OUString("invalid character \"" + OUStringLiteral1(c) + "\"")
         : OUString(
-            "invalid byte x" + OUString::number(c, 16).toAsciiUpperCase());
+            "invalid byte x" + OUString(OUString::number(c, 16)).toAsciiUpperCase());
     return TOK_ERROR;
 }
 
diff --git a/vcl/source/control/field.cxx b/vcl/source/control/field.cxx
index f44d13e18b83..ffc6956d4cf2 100644
--- a/vcl/source/control/field.cxx
+++ b/vcl/source/control/field.cxx
@@ -814,12 +814,12 @@ namespace
         OUStringBuffer aBuf;
         sal_Int32 nTextLen;
 
-        nTextLen = OUString::number(rFormatter.GetMin()).getLength();
+        nTextLen = OUString(OUString::number(rFormatter.GetMin())).getLength();
         string::padToLength(aBuf, nTextLen, '9');
         Size aMinTextSize = rSpinField.CalcMinimumSizeForText(
             rFormatter.CreateFieldText(aBuf.makeStringAndClear().toInt64()));
 
-        nTextLen = OUString::number(rFormatter.GetMax()).getLength();
+        nTextLen = OUString(OUString::number(rFormatter.GetMax())).getLength();
         string::padToLength(aBuf, nTextLen, '9');
         Size aMaxTextSize = rSpinField.CalcMinimumSizeForText(
             rFormatter.CreateFieldText(aBuf.makeStringAndClear().toInt64()));
diff --git a/winaccessibility/source/UAccCOM/AccTextBase.cxx b/winaccessibility/source/UAccCOM/AccTextBase.cxx
index 6fe5130b4c11..9e5c63605df0 100644
--- a/winaccessibility/source/UAccCOM/AccTextBase.cxx
+++ b/winaccessibility/source/UAccCOM/AccTextBase.cxx
@@ -170,7 +170,7 @@ STDMETHODIMP CAccTextBase::get_attributes(long offset, long * startOffset, long
             unsigned long nColor;
             pValue.Value >>= nColor;
             strAttrs.append('#');
-            auto const hex = OUString::number(nColor, 16).toAsciiUpperCase();
+            auto const hex = OUString(OUString::number(nColor, 16)).toAsciiUpperCase();
             for (sal_Int32 j = hex.getLength(); j < 8; ++j) {
                 strAttrs.append('0');
             }
diff --git a/xmloff/source/style/xmlnumfi.cxx b/xmloff/source/style/xmlnumfi.cxx
index 59e40a39d681..133e2a4eace0 100644
--- a/xmloff/source/style/xmlnumfi.cxx
+++ b/xmloff/source/style/xmlnumfi.cxx
@@ -1474,7 +1474,7 @@ SvXMLNumFormatContext::SvXMLNumFormatContext( SvXMLImport& rImport,
         {
             aFormatCode.append( "][$-" );
             // language code in upper hex:
-            aFormatCode.append(OUString::number(static_cast<sal_uInt16>(eLang), 16).toAsciiUpperCase());
+            aFormatCode.append(OUString(OUString::number(static_cast<sal_uInt16>(eLang), 16)).toAsciiUpperCase());
         }
         aFormatCode.append( ']' );
     }
@@ -2029,7 +2029,7 @@ void SvXMLNumFormatContext::AddCurrency( const OUString& rContent, LanguageType
         if ( nLang != LANGUAGE_SYSTEM )
         {
             //  '-' sign and language code in hex:
-            aFormatCode.append("-").append(OUString::number(sal_uInt16(nLang), 16).toAsciiUpperCase());
+            aFormatCode.append("-").append(OUString(OUString::number(sal_uInt16(nLang), 16)).toAsciiUpperCase());
         }
 
         aFormatCode.append( ']' );    // end of "new" currency symbol