loplugin:stringadd improve detection

if one side of the expression is a compile-time-constant, we don't need
to worry about side-effects on the other side

Change-Id: Iee71ea51b327ef244bf39f128f921ac325d74e2b
Reviewed-on: https://gerrit.libreoffice.org/81589
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

36 files changed, 177 insertions, 181 deletions

diff --git a/codemaker/source/cppumaker/cppuoptions.cxx b/codemaker/source/cppumaker/cppuoptions.cxx
index 05c941b2c68a..90f16fdd3332 100644
--- a/codemaker/source/cppumaker/cppuoptions.cxx
+++ b/codemaker/source/cppumaker/cppuoptions.cxx
@@ -311,8 +311,8 @@ OString CppuOptions::prepareHelp()
         "    -nD        = no dependent types are generated.\n"
         "    -G         = generate only target files which does not exists.\n"
         "    -Gc        = generate only target files which content will be changed.\n"
-        "    -X<file>   = extra types which will not be taken into account for generation.\n\n";
-    help += prepareVersion();
+        "    -X<file>   = extra types which will not be taken into account for generation.\n\n" +
+        prepareVersion();
 
     return help;
 }
diff --git a/codemaker/source/javamaker/javaoptions.cxx b/codemaker/source/javamaker/javaoptions.cxx
index 795d1bbf8955..31e43414c68c 100644
--- a/codemaker/source/javamaker/javaoptions.cxx
+++ b/codemaker/source/javamaker/javaoptions.cxx
@@ -234,8 +234,8 @@ OString JavaOptions::prepareHelp()
         "    -nD        = no dependent types are generated.\n"
         "    -G         = generate only target files which does not exists.\n"
         "    -Gc        = generate only target files which content will be changed.\n"
-        "    -X<file>   = extra types which will not be taken into account for generation.\n\n";
-    help += prepareVersion();
+        "    -X<file>   = extra types which will not be taken into account for generation.\n\n" +
+        prepareVersion();
 
     return help;
 }
diff --git a/comphelper/source/misc/backupfilehelper.cxx b/comphelper/source/misc/backupfilehelper.cxx
index 749b9896cb0b..5421f1510ba4 100644
--- a/comphelper/source/misc/backupfilehelper.cxx
+++ b/comphelper/source/misc/backupfilehelper.cxx
@@ -1702,8 +1702,7 @@ namespace comphelper
             if (mbSafeModeDirExists)
             {
                 // adapt work URL to do all repair op's in the correct directory
-                maUserConfigWorkURL += "/";
-                maUserConfigWorkURL += getSafeModeName();
+                maUserConfigWorkURL += "/" + getSafeModeName();
             }
         }
 
diff --git a/compilerplugins/clang/stringadd.cxx b/compilerplugins/clang/stringadd.cxx
index 8b96de07e109..c1023c641bbb 100644
--- a/compilerplugins/clang/stringadd.cxx
+++ b/compilerplugins/clang/stringadd.cxx
@@ -74,11 +74,20 @@ public:
     bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const*);
 
 private:
-    const VarDecl* findAssignOrAdd(Stmt const*);
-    void checkForCompoundAssign(Stmt const* stmt1, Stmt const* stmt2, VarDecl const* varDecl);
+    struct VarDeclAndConstant
+    {
+        const VarDecl* varDecl;
+        bool bCompileTimeConstant;
+        bool bSideEffectFree;
+    };
+
+    VarDeclAndConstant findAssignOrAdd(Stmt const*);
+    void checkForCompoundAssign(Stmt const* stmt1, Stmt const* stmt2,
+                                VarDeclAndConstant const& varDecl);
 
     Expr const* ignore(Expr const*);
     bool isSideEffectFree(Expr const*);
+    bool isCompileTimeConstant(Expr const*);
 };
 
 bool StringAdd::VisitCompoundStmt(CompoundStmt const* compoundStmt)
@@ -91,9 +100,9 @@ bool StringAdd::VisitCompoundStmt(CompoundStmt const* compoundStmt)
     {
         if (it == compoundStmt->body_end())
             break;
-        const VarDecl* foundVar = findAssignOrAdd(*it);
+        VarDeclAndConstant foundVar = findAssignOrAdd(*it);
         // reference types have slightly weird behaviour
-        if (foundVar && !foundVar->getType()->isReferenceType())
+        if (foundVar.varDecl && !foundVar.varDecl->getType()->isReferenceType())
         {
             auto stmt1 = *it;
             ++it;
@@ -109,7 +118,7 @@ bool StringAdd::VisitCompoundStmt(CompoundStmt const* compoundStmt)
     return true;
 }
 
-const VarDecl* StringAdd::findAssignOrAdd(Stmt const* stmt)
+StringAdd::VarDeclAndConstant StringAdd::findAssignOrAdd(Stmt const* stmt)
 {
     if (auto exprCleanup = dyn_cast<ExprWithCleanups>(stmt))
         stmt = exprCleanup->getSubExpr();
@@ -123,14 +132,13 @@ const VarDecl* StringAdd::findAssignOrAdd(Stmt const* stmt)
                 auto tc = loplugin::TypeCheck(varDeclLHS->getType());
                 if (!tc.Class("OUString").Namespace("rtl").GlobalNamespace()
                     && !tc.Class("OString").Namespace("rtl").GlobalNamespace())
-                    return nullptr;
+                    return {};
                 if (varDeclLHS->getStorageDuration() == SD_Static)
-                    return nullptr;
+                    return {};
                 if (!varDeclLHS->hasInit())
-                    return nullptr;
-                if (!isSideEffectFree(varDeclLHS->getInit()))
-                    return nullptr;
-                return varDeclLHS;
+                    return {};
+                return { varDeclLHS, isCompileTimeConstant(varDeclLHS->getInit()),
+                         isSideEffectFree(varDeclLHS->getInit()) };
             }
     if (auto operatorCall = dyn_cast<CXXOperatorCallExpr>(stmt))
         if (operatorCall->getOperator() == OO_Equal || operatorCall->getOperator() == OO_PlusEqual)
@@ -140,16 +148,15 @@ const VarDecl* StringAdd::findAssignOrAdd(Stmt const* stmt)
                     auto tc = loplugin::TypeCheck(varDeclLHS->getType());
                     if (!tc.Class("OUString").Namespace("rtl").GlobalNamespace()
                         && !tc.Class("OString").Namespace("rtl").GlobalNamespace())
-                        return nullptr;
+                        return {};
                     auto rhs = operatorCall->getArg(1);
-                    if (!isSideEffectFree(rhs))
-                        return nullptr;
-                    return varDeclLHS;
+                    return { varDeclLHS, isCompileTimeConstant(rhs), isSideEffectFree(rhs) };
                 }
-    return nullptr;
+    return {};
 }
 
-void StringAdd::checkForCompoundAssign(Stmt const* stmt1, Stmt const* stmt2, VarDecl const* varDecl)
+void StringAdd::checkForCompoundAssign(Stmt const* stmt1, Stmt const* stmt2,
+                                       VarDeclAndConstant const& varDecl)
 {
     // OString additions are frequently wrapped in these
     if (auto exprCleanup = dyn_cast<ExprWithCleanups>(stmt2))
@@ -164,10 +171,14 @@ void StringAdd::checkForCompoundAssign(Stmt const* stmt1, Stmt const* stmt2, Var
     auto declRefExprLHS = dyn_cast<DeclRefExpr>(ignore(operatorCall->getArg(0)));
     if (!declRefExprLHS)
         return;
-    if (declRefExprLHS->getDecl() != varDecl)
+    if (declRefExprLHS->getDecl() != varDecl.varDecl)
         return;
+    // if either side is a compile-time-constant, then we don't care about
+    // side-effects
     auto rhs = operatorCall->getArg(1);
-    if (!isSideEffectFree(rhs))
+    if (varDecl.bCompileTimeConstant || isCompileTimeConstant(rhs))
+        ; // good
+    else if (!varDecl.bSideEffectFree || !isSideEffectFree(rhs))
         return;
     // if we cross a #ifdef boundary
     if (containsPreprocessingConditionalInclusion(
@@ -304,6 +315,16 @@ bool StringAdd::isSideEffectFree(Expr const* expr)
     return false;
 }
 
+bool StringAdd::isCompileTimeConstant(Expr const* expr)
+{
+    expr = compat::IgnoreImplicit(expr);
+    if (auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(expr))
+        if (cxxConstructExpr->getNumArgs() > 0
+            && isa<clang::StringLiteral>(cxxConstructExpr->getArg(0)))
+            return true;
+    return false;
+}
+
 loplugin::Plugin::Registration<StringAdd> stringadd("stringadd");
 }
 
diff --git a/compilerplugins/clang/test/stringadd.cxx b/compilerplugins/clang/test/stringadd.cxx
index a8469026e509..f36bbbca999e 100644
--- a/compilerplugins/clang/test/stringadd.cxx
+++ b/compilerplugins/clang/test/stringadd.cxx
@@ -99,6 +99,13 @@ void f(Bar b1, Bar& b2, Bar* b3)
     // expected-error@+1 {{simplify by merging with the preceding assignment [loplugin:stringadd]}}
     s3 += b3->m_field;
 }
+OUString side_effect();
+void f2()
+{
+    OUString sRet = "xxx";
+    // expected-error@+1 {{simplify by merging with the preceding assignment [loplugin:stringadd]}}
+    sRet += side_effect();
+}
 }
 
 // no warning expected
@@ -117,17 +124,10 @@ void f()
 namespace test5
 {
 OUString side_effect();
-int side_effect2();
 void f()
 {
-    OUString sRet = "xxx";
-    sRet += side_effect();
-    sRet += OUString::number(side_effect2());
-}
-void g()
-{
     OUString sRet = side_effect();
-    sRet += "xxx";
+    sRet += side_effect();
 }
 }
 
diff --git a/cppu/source/uno/EnvStack.cxx b/cppu/source/uno/EnvStack.cxx
index 748557e8b98a..71c87bec7c37 100644
--- a/cppu/source/uno/EnvStack.cxx
+++ b/cppu/source/uno/EnvStack.cxx
@@ -366,8 +366,7 @@ int SAL_CALL uno_Environment_isValid(uno_Environment * pEnv, rtl_uString ** pRea
     }
     else
     {
-        OUString envDcp(UNO_LB_UNO);
-        envDcp += cppu::EnvDcp::getPurpose(pEnv->pTypeName);
+        OUString envDcp = UNO_LB_UNO + cppu::EnvDcp::getPurpose(pEnv->pTypeName);
 
         uno::Environment env(envDcp);
 
diff --git a/filter/source/msfilter/msdffimp.cxx b/filter/source/msfilter/msdffimp.cxx
index e0d17f5247ec..ebe405aefb9d 100644
--- a/filter/source/msfilter/msdffimp.cxx
+++ b/filter/source/msfilter/msdffimp.cxx
@@ -7285,9 +7285,7 @@ SdrOle2Obj* SvxMSDffManager::CreateSdrOLEFromStorage(
         // (that's not the case for e.g. Fontwork )
         // If that's not the case -> include it as graphic
         bool bValidStorage = false;
-        OUString aDstStgName(MSO_OLE_Obj);
-
-        aDstStgName += OUString::number( ++nMSOleObjCntr );
+        OUString aDstStgName = MSO_OLE_Obj + OUString::number( ++nMSOleObjCntr );
 
         {
             tools::SvRef<SotStorage> xObjStg = rSrcStorage->OpenSotStorage( rStorageName );
diff --git a/formula/source/ui/dlg/funcutl.cxx b/formula/source/ui/dlg/funcutl.cxx
index 0d8a8656afd4..b2d018befbd2 100644
--- a/formula/source/ui/dlg/funcutl.cxx
+++ b/formula/source/ui/dlg/funcutl.cxx
@@ -231,8 +231,7 @@ void ArgInput::Show()
 
 void ArgInput::UpdateAccessibleNames()
 {
-    OUString aArgName(":");
-    aArgName += pFtArg->get_label();
+    OUString aArgName = ":" + pFtArg->get_label();
 
     OUString aName = pBtnFx->get_tooltip_text();
     aName += aArgName;
diff --git a/idlc/source/options.cxx b/idlc/source/options.cxx
index d9b0003a60cb..2f2e3bb1e6f9 100644
--- a/idlc/source/options.cxx
+++ b/idlc/source/options.cxx
@@ -285,8 +285,7 @@ bool Options::initOptions(std::vector< std::string > & rArgs)
         {
           return badOption("invalid", option);
         }
-        OString param("-D");
-        param += OString((*first).c_str(), (*first).size());
+        OString param = "-D" + rtl::OStringView((*first).c_str(), (*first).size());
         if (m_options.count("-D") > 0)
         {
           param = m_options["-D"] + " " + param;
@@ -393,8 +392,8 @@ OString Options::prepareHelp() const
          "    -verbose    = verbose output.\n"
          "    -w          = display warning messages.\n"
          "    -we         = treat warnings as errors.\n"
-         "    -h|-?       = print this help message and exit.\n\n";
-    help += prepareVersion();
+         "    -h|-?       = print this help message and exit.\n\n" +
+        prepareVersion();
 
     return help;
 }
diff --git a/io/source/acceptor/acc_socket.cxx b/io/source/acceptor/acc_socket.cxx
index ba6938928bbe..a72179ecb356 100644
--- a/io/source/acceptor/acc_socket.cxx
+++ b/io/source/acceptor/acc_socket.cxx
@@ -168,8 +168,8 @@ namespace io_acceptor {
 
             if(i != nBytesToRead)
             {
-                OUString message("acc_socket.cxx:SocketConnection::read: error - ");
-                message +=  m_socket.getErrorAsString();
+                OUString message = "acc_socket.cxx:SocketConnection::read: error - " +
+                    m_socket.getErrorAsString();
 
                 IOException ioException(message, static_cast<XConnection *>(this));
 
@@ -202,8 +202,8 @@ namespace io_acceptor {
         {
             if( m_socket.write( seq.getConstArray() , seq.getLength() ) != seq.getLength() )
             {
-                OUString message("acc_socket.cxx:SocketConnection::write: error - ");
-                message += m_socket.getErrorAsString();
+                OUString message = "acc_socket.cxx:SocketConnection::write: error - " +
+                    m_socket.getErrorAsString();
 
                 IOException ioException(message, static_cast<XConnection *>(this));
 
diff --git a/io/source/connector/ctr_socket.cxx b/io/source/connector/ctr_socket.cxx
index ab2eefd87872..6523d6408599 100644
--- a/io/source/connector/ctr_socket.cxx
+++ b/io/source/connector/ctr_socket.cxx
@@ -129,8 +129,8 @@ namespace stoc_connector {
 
             if(i != nBytesToRead && m_socket.getError() != osl_Socket_E_None)
             {
-                OUString message("ctr_socket.cxx:SocketConnection::read: error - ");
-                message += m_socket.getErrorAsString();
+                OUString message = "ctr_socket.cxx:SocketConnection::read: error - " +
+                    m_socket.getErrorAsString();
 
                 IOException ioException(message, static_cast<XConnection *>(this));
 
@@ -163,8 +163,8 @@ namespace stoc_connector {
         {
             if( m_socket.write( seq.getConstArray() , seq.getLength() ) != seq.getLength() )
             {
-                OUString message("ctr_socket.cxx:SocketConnection::write: error - ");
-                message += m_socket.getErrorAsString();
+                OUString message = "ctr_socket.cxx:SocketConnection::write: error - "+
+                    m_socket.getErrorAsString();
 
                 IOException ioException(message, static_cast<XConnection *>(this));
 
diff --git a/lotuswordpro/source/filter/lwptblformula.cxx b/lotuswordpro/source/filter/lwptblformula.cxx
index c6af01f6e34f..fa8f39fa0bb4 100644
--- a/lotuswordpro/source/filter/lwptblformula.cxx
+++ b/lotuswordpro/source/filter/lwptblformula.cxx
@@ -101,9 +101,9 @@ void LwpFormulaInfo::ReadText()
     std::vector<char> aBuf(nStrLen + 1);
     m_pObjStrm->QuickRead(aBuf.data(), nStrLen);
     aBuf[nStrLen]= '\0';
-    OUString aText = "\"";
-    aText += OUString(aBuf.data(), nStrLen, osl_getThreadTextEncoding());
-    aText += "\"";
+    OUString aText = "\"" +
+        OUString(aBuf.data(), nStrLen, osl_getThreadTextEncoding()) +
+        "\"";
 
     m_aStack.push_back(std::make_unique<LwpFormulaText>(aText));
 }
diff --git a/lotuswordpro/source/filter/xfilter/xfdrawpath.cxx b/lotuswordpro/source/filter/xfilter/xfdrawpath.cxx
index e9ae753773a4..9061f583f152 100644
--- a/lotuswordpro/source/filter/xfilter/xfdrawpath.cxx
+++ b/lotuswordpro/source/filter/xfilter/xfdrawpath.cxx
@@ -128,9 +128,9 @@ void    XFDrawPath::ToXml(IXFStream *pStrm)
     //view-box:
     XFRect  rect = m_aRect;
 
-    OUString strViewBox = "0 0 ";
-    strViewBox += OUString::number(rect.GetWidth()*1000) + " ";
-    strViewBox += OUString::number(rect.GetHeight()*1000);
+    OUString strViewBox = "0 0 " +
+        OUString::number(rect.GetWidth()*1000) + " " +
+        OUString::number(rect.GetHeight()*1000);
     pAttrList->AddAttribute( "svg:viewBox", strViewBox);
 
     //points
diff --git a/lotuswordpro/source/filter/xfilter/xfdrawpolygon.cxx b/lotuswordpro/source/filter/xfilter/xfdrawpolygon.cxx
index 6b50db7c56ed..dcc12c2dadb8 100644
--- a/lotuswordpro/source/filter/xfilter/xfdrawpolygon.cxx
+++ b/lotuswordpro/source/filter/xfilter/xfdrawpolygon.cxx
@@ -71,9 +71,9 @@ void XFDrawPolygon::ToXml(IXFStream *pStrm)
     pAttrList->Clear();
     //view-box:
     XFRect  rect = CalcViewBox();
-    OUString strViewBox = "0 0 ";
-    strViewBox += OUString::number(rect.GetWidth()*1000) + " ";
-    strViewBox += OUString::number(rect.GetHeight()*1000);
+    OUString strViewBox = "0 0 " +
+        OUString::number(rect.GetWidth()*1000) + " " +
+        OUString::number(rect.GetHeight()*1000);
     pAttrList->AddAttribute( "svg:viewBox", strViewBox);
 
     //points
diff --git a/lotuswordpro/source/filter/xfilter/xfdrawpolyline.cxx b/lotuswordpro/source/filter/xfilter/xfdrawpolyline.cxx
index 2ddeca7f0c58..4cad76ebb3c4 100644
--- a/lotuswordpro/source/filter/xfilter/xfdrawpolyline.cxx
+++ b/lotuswordpro/source/filter/xfilter/xfdrawpolyline.cxx
@@ -71,9 +71,9 @@ void XFDrawPolyline::ToXml(IXFStream *pStrm)
     pAttrList->Clear();
     //view-box:
     XFRect  rect = CalcViewBox();
-    OUString strViewBox = "0 0 ";
-    strViewBox += OUString::number(rect.GetWidth()*1000) + " ";
-    strViewBox += OUString::number(rect.GetHeight()*1000);
+    OUString strViewBox = "0 0 " +
+        OUString::number(rect.GetWidth()*1000) + " " +
+        OUString::number(rect.GetHeight()*1000);
     pAttrList->AddAttribute( "svg:viewBox", strViewBox);
 
     //points
diff --git a/sal/qa/osl/file/osl_File.cxx b/sal/qa/osl/file/osl_File.cxx
index 348b259bc4e0..6b17d07098c6 100644
--- a/sal/qa/osl/file/osl_File.cxx
+++ b/sal/qa/osl/file/osl_File.cxx
@@ -967,11 +967,12 @@ namespace osl_FileBase
 
         bool bOk = compareFileName(aUStr, aUResultURL);
 
-        OString sError = "test for getSystemPathFromFileURL(' " +
+        OString sError =
+            "test for getSystemPathFromFileURL(' " +
             OUStringToOString(aUNormalURL, RTL_TEXTENCODING_ASCII_US) +
-            " ') function:use an absolute file URL, ";
-        sError += outputError(OUStringToOString(aUStr, RTL_TEXTENCODING_ASCII_US),
-                            OUStringToOString(aUResultURL, RTL_TEXTENCODING_ASCII_US));
+            " ') function:use an absolute file URL, " +
+            outputError(OUStringToOString(aUStr, RTL_TEXTENCODING_ASCII_US),
+                        OUStringToOString(aUResultURL, RTL_TEXTENCODING_ASCII_US));
 
         CPPUNIT_ASSERT_EQUAL_MESSAGE(sError.getStr(), osl::FileBase::E_None, nError);
         CPPUNIT_ASSERT_MESSAGE(sError.getStr(), bOk);
@@ -990,11 +991,12 @@ namespace osl_FileBase
 
         bool bOk = compareFileName(aUStr, aUResultURL);
 
-        OString sError = "test for getSystemPathFromFileURL(' " +
+        OString sError =
+            "test for getSystemPathFromFileURL(' " +
             OUStringToOString(aUNormalURL, RTL_TEXTENCODING_ASCII_US) +
-                " ') function:use a CJK coded absolute URL, ";
-        sError += outputError(OUStringToOString(aUStr, RTL_TEXTENCODING_ASCII_US),
-                            OUStringToOString(aUResultURL, RTL_TEXTENCODING_ASCII_US));
+            " ') function:use a CJK coded absolute URL, " +
+            outputError(OUStringToOString(aUStr, RTL_TEXTENCODING_ASCII_US),
+                        OUStringToOString(aUResultURL, RTL_TEXTENCODING_ASCII_US));
         deleteTestDirectory(aTmpName10);
 
         CPPUNIT_ASSERT_EQUAL_MESSAGE(sError.getStr(), osl::FileBase::E_None, nError);
diff --git a/sc/source/ui/unoobj/cellvaluebinding.cxx b/sc/source/ui/unoobj/cellvaluebinding.cxx
index 8063ecf4b54e..a5d43ab012e2 100644
--- a/sc/source/ui/unoobj/cellvaluebinding.cxx
+++ b/sc/source/ui/unoobj/cellvaluebinding.cxx
@@ -405,9 +405,9 @@ namespace calc
         OCellValueBinding* pNonConstThis = const_cast< OCellValueBinding* >( this );
         if ( !pNonConstThis->supportsType( _rType ) )
         {
-            OUString sMessage( "The given type (" );
-            sMessage += _rType.getTypeName();
-            sMessage += ") is not supported by this binding.";
+            OUString sMessage = "The given type (" +
+                _rType.getTypeName() +
+                ") is not supported by this binding.";
                 // TODO: localize this error message
 
             throw IncompatibleTypesException( sMessage, *pNonConstThis );
diff --git a/sfx2/source/control/request.cxx b/sfx2/source/control/request.cxx
index d4f48cccc012..fcdb5c036f32 100644
--- a/sfx2/source/control/request.cxx
+++ b/sfx2/source/control/request.cxx
@@ -333,9 +333,7 @@ void SfxRequest_Impl::Record
 */
 
 {
-    OUString aCommand(".uno:");
-    aCommand += OUString( pSlot->GetUnoName(), strlen( pSlot->GetUnoName() ), RTL_TEXTENCODING_UTF8 );
-    OUString aCmd( aCommand );
+    OUString aCmd = ".uno:" + OUString::createFromAscii( pSlot->GetUnoName() );
     if(!xRecorder.is())
         return;
 
diff --git a/sot/source/sdstor/ucbstorage.cxx b/sot/source/sdstor/ucbstorage.cxx
index 5340f841454c..7ca803627124 100644
--- a/sot/source/sdstor/ucbstorage.cxx
+++ b/sot/source/sdstor/ucbstorage.cxx
@@ -1480,9 +1480,8 @@ UCBStorage_Impl::UCBStorage_Impl( const OUString& rName, StreamMode nMode, UCBSt
     if ( m_bIsRoot )
     {
         // create the special package URL for the package content
-        OUString aTemp = "vnd.sun.star.pkg://";
-        aTemp += INetURLObject::encode( aName, INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All );
-        m_aURL = aTemp;
+        m_aURL = "vnd.sun.star.pkg://" +
+            INetURLObject::encode( aName, INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All );
 
         if ( m_nMode & StreamMode::WRITE )
         {
@@ -1521,9 +1520,8 @@ UCBStorage_Impl::UCBStorage_Impl( SvStream& rStream, UCBStorage* pStorage, bool
     // UCBStorages work on a content, so a temporary file for a content must be created, even if the stream is only
     // accessed readonly
     // the root storage opens the package; create the special package URL for the package content
-    OUString aTemp = "vnd.sun.star.pkg://";
-    aTemp += INetURLObject::encode( m_pTempFile->GetURL(), INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All );
-    m_aURL = aTemp;
+    m_aURL = "vnd.sun.star.pkg://" +
+        INetURLObject::encode( m_pTempFile->GetURL(), INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All );
 
     // copy data into the temporary file
     std::unique_ptr<SvStream> pStream(::utl::UcbStreamHelper::CreateStream( m_pTempFile->GetURL(), StreamMode::STD_READWRITE, true /* bFileExists */ ));
diff --git a/svl/qa/unit/svl.cxx b/svl/qa/unit/svl.cxx
index 4b9300d5a1bf..17035f29dc86 100644
--- a/svl/qa/unit/svl.cxx
+++ b/svl/qa/unit/svl.cxx
@@ -415,8 +415,8 @@ void Test::checkPreviewString(SvNumberFormatter& aFormatter,
             "\", " +
             OString::number( fPreviewNumber ) +
             ", sStr, ppColor, ";
-        aMessage += OString::number( static_cast<sal_uInt16>(eLang) );
-        aMessage += " ) failed";
+        aMessage += OString::number( static_cast<sal_uInt16>(eLang) ) +
+            " ) failed";
         CPPUNIT_FAIL( aMessage.getStr() );
     }
     CPPUNIT_ASSERT_EQUAL(sExpected, sStr);
diff --git a/svx/source/dialog/hexcolorcontrol.cxx b/svx/source/dialog/hexcolorcontrol.cxx
index a387a427687d..8cd9089c7051 100644
--- a/svx/source/dialog/hexcolorcontrol.cxx
+++ b/svx/source/dialog/hexcolorcontrol.cxx
@@ -70,8 +70,7 @@ Color HexColorControl::GetColor() const
 {
     sal_Int32 nColor = -1;
 
-    OUString aStr("#");
-    aStr += m_xEntry->get_text();
+    OUString aStr = "#" + m_xEntry->get_text();
     sal_Int32 nLen = aStr.getLength();
 
     if (nLen < 7)
diff --git a/svx/source/form/fmcontrollayout.cxx b/svx/source/form/fmcontrollayout.cxx
index 7d503519650f..5fcea4b7d6bc 100644
--- a/svx/source/form/fmcontrollayout.cxx
+++ b/svx/source/form/fmcontrollayout.cxx
@@ -74,8 +74,8 @@ namespace svxform
     {
         ::utl::OConfigurationNode getLayoutSettings( DocumentType _eDocType )
         {
-            OUString sConfigName = "/org.openoffice.Office.Common/Forms/ControlLayout/";
-            sConfigName += DocumentClassification::getModuleIdentifierForDocumentType( _eDocType );
+            OUString sConfigName = "/org.openoffice.Office.Common/Forms/ControlLayout/" +
+                DocumentClassification::getModuleIdentifierForDocumentType( _eDocType );
             return OConfigurationTreeRoot::createWithComponentContext(
                 ::comphelper::getProcessComponentContext(),    // TODO
                 sConfigName );
diff --git a/svx/source/form/fmtextcontrolshell.cxx b/svx/source/form/fmtextcontrolshell.cxx
index 6b8e42bfe340..e709b9c7fa86 100644
--- a/svx/source/form/fmtextcontrolshell.cxx
+++ b/svx/source/form/fmtextcontrolshell.cxx
@@ -566,9 +566,9 @@ namespace svx
                 sUnoSlotName = lcl_getUnoSlotName( nSlotId );
             else
                 sUnoSlotName = "<unknown>";
-            OString sUnoSlotNameAscii( "\"" );
-            sUnoSlotNameAscii += OString( sUnoSlotName.getStr(), sUnoSlotName.getLength(), RTL_TEXTENCODING_ASCII_US );
-            sUnoSlotNameAscii += "\"";
+            OString sUnoSlotNameAscii = "\"" +
+                OString( sUnoSlotName.getStr(), sUnoSlotName.getLength(), RTL_TEXTENCODING_ASCII_US ) +
+                "\"";
 #endif
 
             if ( _bTranslateLatin )
diff --git a/svx/source/gallery2/galtheme.cxx b/svx/source/gallery2/galtheme.cxx
index e02802525313..fa3ab3ea9167 100644
--- a/svx/source/gallery2/galtheme.cxx
+++ b/svx/source/gallery2/galtheme.cxx
@@ -303,9 +303,7 @@ INetURLObject GalleryTheme::ImplCreateUniqueURL( SgaObjKind eObjKind, ConvertDat
         }
         else
         {
-            OUString aFileName( "dd" );
-
-            aFileName += OUString::number( ++nNextNumber % 999999 );
+            OUString aFileName = "dd" + OUString::number( ++nNextNumber % 999999 );
 
             if (pExt)
                 aFileName += OUString( pExt, strlen(pExt), RTL_TEXTENCODING_ASCII_US );
diff --git a/svx/source/svdraw/svdmrkv.cxx b/svx/source/svdraw/svdmrkv.cxx
index c012cc0fb10e..56a1ef2b91a6 100644
--- a/svx/source/svdraw/svdmrkv.cxx
+++ b/svx/source/svdraw/svdmrkv.cxx
@@ -953,13 +953,13 @@ void SdrMarkView::SetMarkHandles(SfxViewShell* pOtherShell)
 
                                                     aSelection = OutputDevice::LogicToLogic(aSelection, MapMode(MapUnit::MapTwip), MapMode(MapUnit::Map100thMM));
 
-                                                    OString sSVGElem(R"elem(<svg version=\"1.2\" width=\")elem");
-                                                    sSVGElem += OString::number(aSelection.GetWidth() / 100.0);
-                                                    sSVGElem += R"elem(mm\" height=\")elem";
-                                                    sSVGElem += OString::number(aSelection.GetHeight() / 100.0);
-                                                    sSVGElem += R"elem(mm\" viewBox=\")elem";
-                                                    sSVGElem += aSelection.toString();
-                                                    sSVGElem += R"elem(\" preserveAspectRatio=\"xMidYMid\" xmlns=\"http://www.w3.org/2000/svg\">)elem";
+                                                    OString sSVGElem = R"elem(<svg version=\"1.2\" width=\")elem" +
+                                                        OString::number(aSelection.GetWidth() / 100.0) +
+                                                        R"elem(mm\" height=\")elem" +
+                                                        OString::number(aSelection.GetHeight() / 100.0) +
+                                                        R"elem(mm\" viewBox=\")elem" +
+                                                        aSelection.toString() +
+                                                        R"elem(\" preserveAspectRatio=\"xMidYMid\" xmlns=\"http://www.w3.org/2000/svg\">)elem";
 
                                                     aExtraInfo.append(", \"svg\": \"");
                                                     aExtraInfo.append(sSVGElem);
@@ -982,8 +982,7 @@ void SdrMarkView::SetMarkHandles(SfxViewShell* pOtherShell)
                 sSelectionText += OStringLiteral(", ") + OString::number(nRotAngle);
                 if (!aExtraInfo.isEmpty())
                 {
-                    sSelectionText += ", ";
-                    sSelectionText += aExtraInfo.makeStringAndClear();
+                    sSelectionText += ", " + aExtraInfo.makeStringAndClear();
                 }
             }
 
diff --git a/sw/qa/extras/layout/layout.cxx b/sw/qa/extras/layout/layout.cxx
index d8cef7ef98aa..5b90067a174f 100644
--- a/sw/qa/extras/layout/layout.cxx
+++ b/sw/qa/extras/layout/layout.cxx
@@ -3168,10 +3168,9 @@ CPPUNIT_TEST_FIXTURE(SwLayoutWriter, testShapeAllowOverlap)
     // <bounds left="1984" top="1984" width="1137" height="1137"/>
     // <bounds left="2551" top="2551" width="1137" height="1137"/>
     // so there was a clear vertical overlap. (Allow for 1px tolerance.)
-    OString aMessage("Unexpected overlap: first shape's bottom is ");
-    aMessage += OString::number(pFirst->GetObjRect().Bottom());
-    aMessage += ", second shape's top is ";
-    aMessage += OString::number(pSecond->GetObjRect().Top());
+    OString aMessage = "Unexpected overlap: first shape's bottom is "
+                       + OString::number(pFirst->GetObjRect().Bottom()) + ", second shape's top is "
+                       + OString::number(pSecond->GetObjRect().Top());
     CPPUNIT_ASSERT_MESSAGE(aMessage.getStr(),
                            std::abs(pFirst->GetObjRect().Bottom() - pSecond->GetObjRect().Top())
                                < 15);
diff --git a/sw/qa/extras/rtfexport/rtfexport2.cxx b/sw/qa/extras/rtfexport/rtfexport2.cxx
index c90f4ca201db..ff63ac7db40f 100644
--- a/sw/qa/extras/rtfexport/rtfexport2.cxx
+++ b/sw/qa/extras/rtfexport/rtfexport2.cxx
@@ -746,8 +746,7 @@ DECLARE_RTFEXPORT_TEST(testFdo52989, "fdo52989.rtf")
 {
     // Same as n#192129, but for JPEG files.
     uno::Reference<drawing::XShape> xShape = getShape(1);
-    OString aMessage("xShape->getSize().Width() = ");
-    aMessage += OString::number(xShape->getSize().Width);
+    OString aMessage = "xShape->getSize().Width() = " + OString::number(xShape->getSize().Width);
 
     // This was 2, should be 423 (or 369?).
     CPPUNIT_ASSERT_MESSAGE(aMessage.getStr(), xShape->getSize().Width >= 273);
diff --git a/sw/source/core/doc/dbgoutsw.cxx b/sw/source/core/doc/dbgoutsw.cxx
index 62cd9e4da77e..26792bd8e3a0 100644
--- a/sw/source/core/doc/dbgoutsw.cxx
+++ b/sw/source/core/doc/dbgoutsw.cxx
@@ -279,15 +279,14 @@ const char * dbg_out(const SfxItemSet & rSet)
 
 static OUString lcl_dbg_out(const SwTextAttr & rAttr)
 {
-    OUString aStr("[ ");
-
-    aStr += OUString::number(rAttr.GetStart());
-    aStr += "->";
-    aStr += OUString::number(*rAttr.End());
-    aStr += " ";
-    aStr += lcl_dbg_out(rAttr.GetAttr());
-
-    aStr += " ]";
+    OUString aStr =
+        "[ " +
+        OUString::number(rAttr.GetStart()) +
+        "->" +
+        OUString::number(*rAttr.End()) +
+        " " +
+        lcl_dbg_out(rAttr.GetAttr()) +
+        " ]";
 
     return aStr;
 }
@@ -320,16 +319,14 @@ const char * dbg_out(const SwpHints &rHints)
 
 static OUString lcl_dbg_out(const SwPosition & rPos)
 {
-    OUString aStr("( ");
-
-    aStr += OUString::number(rPos.nNode.GetIndex());
-    aStr += ", ";
-    aStr += OUString::number(rPos.nContent.GetIndex());
-    aStr += ": ";
-    aStr += OUString::number
-        (reinterpret_cast<sal_IntPtr>(rPos.nContent.GetIdxReg()), 16);
-
-    aStr += " )";
+    OUString aStr =
+        "( " +
+        OUString::number(rPos.nNode.GetIndex()) +
+        ", " +
+        OUString::number(rPos.nContent.GetIndex()) +
+        ": " +
+        OUString::number(reinterpret_cast<sal_IntPtr>(rPos.nContent.GetIdxReg()), 16) +
+        " )";
 
     return aStr;
 }
@@ -341,9 +338,9 @@ const char * dbg_out(const SwPosition & rPos)
 
 static OUString lcl_dbg_out(const SwPaM & rPam)
 {
-    OUString aStr("[ Pt: ");
-
-    aStr += lcl_dbg_out(*rPam.GetPoint());
+    OUString aStr =
+        "[ Pt: " +
+        lcl_dbg_out(*rPam.GetPoint());
 
     if (rPam.HasMark())
     {
@@ -373,17 +370,16 @@ const char * dbg_out(const SwNodeNum & rNum)
 
 static OUString lcl_dbg_out(const SwRect & rRect)
 {
-    OUString aResult("[ [");
-
-    aResult += OUString::number(rRect.Left());
-    aResult += ", ";
-    aResult += OUString::number(rRect.Top());
-    aResult += "], [";
-    aResult += OUString::number(rRect.Right());
-    aResult += ", ";
-    aResult += OUString::number(rRect.Bottom());
-
-    aResult += "] ]";
+    OUString aResult =
+        "[ [" +
+        OUString::number(rRect.Left()) +
+        ", " +
+        OUString::number(rRect.Top()) +
+        "], [" +
+        OUString::number(rRect.Right()) +
+        ", " +
+        OUString::number(rRect.Bottom()) +
+        "] ]";
 
     return aResult;
 }
@@ -857,13 +853,12 @@ const char * dbg_out(const SwFormTokens & rTokens)
 
 static OUString lcl_dbg_out(const SwNodeRange & rRange)
 {
-    OUString aStr("[");
-
-    aStr += lcl_dbg_out(SwPosition(rRange.aStart));
-    aStr += ", ";
-    aStr += lcl_dbg_out(SwPosition(rRange.aEnd));
-
-    aStr += "]";
+    OUString aStr =
+        "[" +
+        lcl_dbg_out(SwPosition(rRange.aStart)) +
+        ", " +
+        lcl_dbg_out(SwPosition(rRange.aEnd)) +
+        "]";
 
     return aStr;
 }
diff --git a/sw/source/filter/html/htmlnumwriter.cxx b/sw/source/filter/html/htmlnumwriter.cxx
index cb21883db528..0d20869ee8be 100644
--- a/sw/source/filter/html/htmlnumwriter.cxx
+++ b/sw/source/filter/html/htmlnumwriter.cxx
@@ -186,8 +186,7 @@ Writer& OutHTML_NumBulListStart( SwHTMLWriter& rWrt,
         rWrt.OutNewLine(); // <OL>/<UL> in a new row
 
         rWrt.m_aBulletGrfs[i].clear();
-        OString sOut = "<";
-        sOut += rWrt.GetNamespace();
+        OString sOut = "<" + rWrt.GetNamespace();
         const SwNumFormat& rNumFormat = rInfo.GetNumRule()->Get( i );
         sal_Int16 eType = rNumFormat.GetNumberingType();
         if( SVX_NUM_CHAR_SPECIAL == eType )
diff --git a/sw/source/filter/xml/xmltexte.cxx b/sw/source/filter/xml/xmltexte.cxx
index b2ae6f5ff08c..509784e78818 100644
--- a/sw/source/filter/xml/xmltexte.cxx
+++ b/sw/source/filter/xml/xmltexte.cxx
@@ -561,8 +561,7 @@ void SwXMLTextParagraphExport::_exportTextEmbedded(
     }
     if( SV_EMBEDDED_OUTPLACE==nType || SV_EMBEDDED_OWN==nType )
     {
-        OUString sURL(XML_EMBEDDEDOBJECTGRAPHIC_URL_BASE);
-        sURL += rOLEObj.GetCurrentPersistName();
+        OUString sURL = XML_EMBEDDEDOBJECTGRAPHIC_URL_BASE + rOLEObj.GetCurrentPersistName();
         if( !(rXMLExport.getExportFlags() & SvXMLExportFlags::EMBEDDED) )
         {
             sURL = GetExport().AddEmbeddedObject( sURL );
diff --git a/sw/source/uibase/dbui/dbmgr.cxx b/sw/source/uibase/dbui/dbmgr.cxx
index c127143bf848..2fa0ee8a4055 100644
--- a/sw/source/uibase/dbui/dbmgr.cxx
+++ b/sw/source/uibase/dbui/dbmgr.cxx
@@ -272,8 +272,8 @@ void SAL_CALL SwDataSourceRemovedListener::revokedDatabaseLocation(const sdb::Da
         return;
 
     OUString aOwnURL = pDocShell->GetMedium()->GetURLObject().GetMainURL(INetURLObject::DecodeMechanism::WithCharset);
-    OUString sTmpName = "vnd.sun.star.pkg://";
-    sTmpName += INetURLObject::encode(aOwnURL, INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All);
+    OUString sTmpName = "vnd.sun.star.pkg://" +
+        INetURLObject::encode(aOwnURL, INetURLObject::PART_AUTHORITY, INetURLObject::EncodeMechanism::All);
     sTmpName += "/" + m_pDBManager->getEmbeddedName();
 
     if (sTmpName != rEvent.OldLocation)
@@ -2625,15 +2625,15 @@ uno::Any GetDBunoURI(const INetURLObject &rURL, DBConnURIType& rType)
         break;
     case DBConnURIType::CALC:
     {
-        OUString sDBURL("sdbc:calc:");
-        sDBURL += rURL.GetMainURL(INetURLObject::DecodeMechanism::NONE);
+        OUString sDBURL = "sdbc:calc:" +
+            rURL.GetMainURL(INetURLObject::DecodeMechanism::NONE);
         aURLAny <<= sDBURL;
     }
     break;
     case DBConnURIType::WRITER:
     {
-        OUString sDBURL("sdbc:writer:");
-        sDBURL += rURL.GetMainURL(INetURLObject::DecodeMechanism::NONE);
+        OUString sDBURL = "sdbc:writer:" +
+            rURL.GetMainURL(INetURLObject::DecodeMechanism::NONE);
         aURLAny <<= sDBURL;
     }
     break;
@@ -2642,8 +2642,8 @@ uno::Any GetDBunoURI(const INetURLObject &rURL, DBConnURIType& rType)
         INetURLObject aUrlTmp(rURL);
         aUrlTmp.removeSegment();
         aUrlTmp.removeFinalSlash();
-        OUString sDBURL("sdbc:dbase:");
-        sDBURL += aUrlTmp.GetMainURL(INetURLObject::DecodeMechanism::NONE);
+        OUString sDBURL = "sdbc:dbase:" +
+            aUrlTmp.GetMainURL(INetURLObject::DecodeMechanism::NONE);
         aURLAny <<= sDBURL;
     }
     break;
@@ -2652,9 +2652,9 @@ uno::Any GetDBunoURI(const INetURLObject &rURL, DBConnURIType& rType)
         INetURLObject aUrlTmp(rURL);
         aUrlTmp.removeSegment();
         aUrlTmp.removeFinalSlash();
-        OUString sDBURL("sdbc:flat:");
-        //only the 'path' has to be added
-        sDBURL += aUrlTmp.GetMainURL(INetURLObject::DecodeMechanism::NONE);
+        OUString sDBURL = "sdbc:flat:" +
+            //only the 'path' has to be added
+            aUrlTmp.GetMainURL(INetURLObject::DecodeMechanism::NONE);
         aURLAny <<= sDBURL;
     }
     break;
diff --git a/ucb/source/ucp/ftp/ftpurl.cxx b/ucb/source/ucp/ftp/ftpurl.cxx
index c1c35b5db02e..413b89c8605c 100644
--- a/ucb/source/ucp/ftp/ftpurl.cxx
+++ b/ucb/source/ucp/ftp/ftpurl.cxx
@@ -715,15 +715,13 @@ OUString FTPURL::ren(const OUString& NewTitle)
     CURL *curl = m_pFCP->handle();
 
     // post request
-    OString renamefrom("RNFR ");
     OUString OldTitle = net_title();
-    renamefrom +=
+    OString renamefrom = "RNFR " +
         OString(OldTitle.getStr(),
                      OldTitle.getLength(),
                      RTL_TEXTENCODING_UTF8);
 
-    OString renameto("RNTO ");
-    renameto +=
+    OString renameto = "RNTO " +
         OString(NewTitle.getStr(),
                      NewTitle.getLength(),
                      RTL_TEXTENCODING_UTF8);
diff --git a/writerfilter/source/dmapper/OLEHandler.cxx b/writerfilter/source/dmapper/OLEHandler.cxx
index 123475515522..3750398c0800 100644
--- a/writerfilter/source/dmapper/OLEHandler.cxx
+++ b/writerfilter/source/dmapper/OLEHandler.cxx
@@ -284,8 +284,7 @@ OUString OLEHandler::copyOLEOStream(
         //hack to work with the ImportEmbeddedObjectResolver
         static sal_Int32 nObjectCount = 100;
         uno::Reference< container::XNameAccess > xNA( xEmbeddedResolver, uno::UNO_QUERY_THROW );
-        OUString aURL("Obj");
-        aURL += OUString::number( nObjectCount++ );
+        OUString aURL = "Obj" + OUString::number( nObjectCount++ );
         uno::Reference < io::XOutputStream > xOLEStream;
         if( (xNA->getByName( aURL ) >>= xOLEStream) && xOLEStream.is() )
         {
diff --git a/xmlhelp/source/cxxhelp/provider/urlparameter.cxx b/xmlhelp/source/cxxhelp/provider/urlparameter.cxx
index 8e99fe22df03..6893c17cc213 100644
--- a/xmlhelp/source/cxxhelp/provider/urlparameter.cxx
+++ b/xmlhelp/source/cxxhelp/provider/urlparameter.cxx
@@ -819,11 +819,11 @@ InputStreamTransformer::InputStreamTransformer( URLParameter* urlParam,
 
         OUString xslURL = pDatabases->getInstallPathAsURL();
 
-        OString xslURLascii(
-            xslURL.getStr(),
-            xslURL.getLength(),
-            RTL_TEXTENCODING_UTF8);
-        xslURLascii += "main_transform.xsl";
+        OString xslURLascii = OString(
+                xslURL.getStr(),
+                xslURL.getLength(),
+                RTL_TEXTENCODING_UTF8) +
+            "main_transform.xsl";
 
         ugblData = &userData;
 
diff --git a/xmloff/source/core/unointerfacetouniqueidentifiermapper.cxx b/xmloff/source/core/unointerfacetouniqueidentifiermapper.cxx
index 6a7f4c7cac73..82159e0175fc 100644
--- a/xmloff/source/core/unointerfacetouniqueidentifiermapper.cxx
+++ b/xmloff/source/core/unointerfacetouniqueidentifiermapper.cxx
@@ -44,8 +44,7 @@ const OUString& UnoInterfaceToUniqueIdentifierMapper::registerReference( const R
     }
     else
     {
-        OUString aId( "id" );
-        aId += OUString::number( mnNextId++ );
+        OUString aId = "id" + OUString::number( mnNextId++ );
         return (*maEntries.emplace( aId, xRef ).first).first;
     }
 }
diff --git a/xmloff/source/draw/sdxmlexp.cxx b/xmloff/source/draw/sdxmlexp.cxx
index 930539053467..212f6060edae 100644
--- a/xmloff/source/draw/sdxmlexp.cxx
+++ b/xmloff/source/draw/sdxmlexp.cxx
@@ -689,8 +689,8 @@ bool SdXMLExport::ImpPrepAutoLayoutInfo(const Reference<XDrawPage>& xPage, OUStr
                 {
                     pNew = new ImpXMLAutoLayoutInfo(nType, pInfo);
                     mvAutoLayoutInfoList.emplace_back( pNew );
-                    OUString sNewName = "AL";
-                    sNewName += OUString::number(mvAutoLayoutInfoList.size() - 1);
+                    OUString sNewName =
+                        "AL" + OUString::number(mvAutoLayoutInfoList.size() - 1);
                     sNewName += "T" + OUString::number(nType);
                     pNew->SetLayoutName(sNewName);
                 }