Prevent += called on temporary O[U]String instances

...found regression e31205f3ec1f941ab5a188bfde6329edf2acc55b
"EditUndoRemoveChars::GetStr must return a reference" and dubious code
0e23f7b0839df68d277186b4df54ba391ac3406a "Lets assume this doesn't want to
update m_pForcedPrefix->GetText() anyway" in addition to the apparent sillies
directly fixed in this commit.

Introduces HAVE_CXX11_REF_QUALIFIER.

Change-Id: I564e98254fd53c1dd9b34193d7057c59721ee24c

2 files changed, 38 insertions, 1 deletions

diff --git a/include/rtl/string.hxx b/include/rtl/string.hxx
index 2caafc2369c7..ad143f5ae047 100644
--- a/include/rtl/string.hxx
+++ b/include/rtl/string.hxx
@@ -33,6 +33,7 @@
 #include <rtl/stringutils.hxx>
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+#include <config_global.h>
 #include <rtl/stringconcat.hxx>
 #endif
 
@@ -309,10 +310,16 @@ public:
       @param    str         a OString.
     */
     OString & operator+=( const OString & str )
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+        &
+#endif
     {
         rtl_string_newConcat( &pData, pData, str.pData );
         return *this;
     }
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+    void operator+=(OString const &) && = delete;
+#endif
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
     /**
@@ -321,6 +328,9 @@ public:
     */
     template< typename T1, typename T2 >
     OString& operator+=( const OStringConcat< T1, T2 >& c )
+#if HAVE_CXX11_REF_QUALIFIER
+        &
+#endif
     {
         sal_Int32 l = c.length();
         if( l == 0 )
@@ -332,6 +342,10 @@ public:
         pData->length = l;
         return *this;
     }
+#if HAVE_CXX11_REF_QUALIFIER
+    template<typename T1, typename T2> void operator +=(
+        OStringConcat<T1, T2> const &) && = delete;
+#endif
 #endif
 
     /**
diff --git a/include/rtl/ustring.hxx b/include/rtl/ustring.hxx
index ee96da1722fc..398dd93fbfd3 100644
--- a/include/rtl/ustring.hxx
+++ b/include/rtl/ustring.hxx
@@ -34,6 +34,7 @@
 #include <sal/log.hxx>
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
+#include <config_global.h>
 #include <rtl/stringconcat.hxx>
 #endif
 
@@ -419,10 +420,16 @@ public:
       @param    str         a OUString.
     */
     OUString & operator+=( const OUString & str )
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+        &
+#endif
     {
         rtl_uString_newConcat( &pData, pData, str.pData );
         return *this;
     }
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+    void operator+=(OUString const &) && = delete;
+#endif
 
     /** Append an ASCII string literal to this string.
 
@@ -432,7 +439,11 @@ public:
     */
     template<typename T>
     typename libreoffice_internal::ConstCharArrayDetector<T, OUString &>::Type
-    operator +=(T & literal) {
+    operator +=(T & literal)
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+        &
+#endif
+    {
         assert(
             libreoffice_internal::ConstCharArrayDetector<T>::isValid(literal));
         rtl_uString_newConcatAsciiL(
@@ -441,6 +452,11 @@ public:
             libreoffice_internal::ConstCharArrayDetector<T>::length);
         return *this;
     }
+#if defined LIBO_INTERNAL_ONLY && HAVE_CXX11_REF_QUALIFIER
+    template<typename T>
+    typename libreoffice_internal::ConstCharArrayDetector<T, OUString &>::Type
+    operator +=(T &) && = delete;
+#endif
 
 #ifdef LIBO_INTERNAL_ONLY // "RTL_FAST_STRING"
     /**
@@ -449,6 +465,9 @@ public:
     */
     template< typename T1, typename T2 >
     OUString& operator+=( const OUStringConcat< T1, T2 >& c )
+#if HAVE_CXX11_REF_QUALIFIER
+        &
+#endif
     {
         sal_Int32 l = c.length();
         if( l == 0 )
@@ -460,6 +479,10 @@ public:
         pData->length = l;
         return *this;
     }
+#if HAVE_CXX11_REF_QUALIFIER
+    template<typename T1, typename T2> void operator +=(
+        OUStringConcat<T1, T2> const &) && = delete;
+#endif
 #endif
 
     /**