clang-tidy: fix `performance-unnecessary-copy-initialization` lints

Source/CursesDialog/cmCursesMainForm.cxx

@@ -617,7 +617,7 @@ void cmCursesMainForm::FillCacheManagerFromUI()
     cmValue existingValue =
       this->CMakeInstance->GetState()->GetCacheEntryValue(cacheKey);
     if (existingValue) {
-      std::string oldValue = *existingValue;
+      std::string const& oldValue = *existingValue;
       std::string newValue = entry.Entry->GetValue();
       std::string fixedOldValue;
       std::string fixedNewValue;

Source/QtDialog/QCMakeCacheView.cxx

@@ -303,7 +303,7 @@ void QCMakeCacheModel::setProperties(const QCMakePropertyList& props)
 
       int num = props2.size();
       for (int i = 0; i < num; i++) {
-        QCMakeProperty prop = props2[i];
+        QCMakeProperty const& prop = props2[i];
         QList<QStandardItem*> items;
         items.append(new QStandardItem());
         items.append(new QStandardItem());
@@ -325,7 +325,7 @@ void QCMakeCacheModel::setProperties(const QCMakePropertyList& props)
 
       int num = props2.size();
       for (int i = 0; i < num; i++) {
-        QCMakeProperty prop = props2[i];
+        QCMakeProperty const& prop = props2[i];
         QList<QStandardItem*> items;
         items.append(new QStandardItem());
         items.append(new QStandardItem());

Source/cmCTest.cxx

@@ -2804,7 +2804,7 @@ bool cmCTest::HandleTestActionArgument(const char* ctestExec, size_t& i,
                                        const std::vector<std::string>& args)
 {
   bool success = true;
-  std::string arg = args[i];
+  std::string const& arg = args[i];
   if (this->CheckArgument(arg, "-T"_s, "--test-action") &&
       (i < args.size() - 1)) {
     this->Impl->ProduceXML = true;
@@ -2836,7 +2836,7 @@ bool cmCTest::HandleTestModelArgument(const char* ctestExec, size_t& i,
                                       const std::vector<std::string>& args)
 {
   bool success = true;
-  std::string arg = args[i];
+  std::string const& arg = args[i];
   if (this->CheckArgument(arg, "-M"_s, "--test-model") &&
       (i < args.size() - 1)) {
     i++;

Source/cmDependsFortran.cxx

@@ -478,7 +478,7 @@ bool cmDependsFortran::CopyModule(const std::vector<std::string>& args)
   // when the interface described in the module does not.
 
   std::string mod = args[2];
-  std::string stamp = args[3];
+  std::string const& stamp = args[3];
   std::string compilerId;
   if (args.size() >= 5) {
     compilerId = args[4];

Source/cmFileCommand.cxx

@@ -285,7 +285,7 @@ bool HandleStringsCommand(std::vector<std::string> const& args,
   }
 
   // Get the variable in which to store the results.
-  std::string outVar = args[2];
+  std::string const& outVar = args[2];
 
   // Parse the options.
   enum

Source/cmGeneratorExpressionNode.cxx

@@ -413,7 +413,7 @@ static const struct TargetExistsNode : public cmGeneratorExpressionNode
       return std::string();
     }
 
-    std::string targetName = parameters.front();
+    std::string const& targetName = parameters.front();
     if (targetName.empty() ||
         !cmGeneratorExpression::IsValidTargetName(targetName)) {
       reportError(context, content->GetOriginalExpression(),
@@ -445,7 +445,7 @@ static const struct TargetNameIfExistsNode : public cmGeneratorExpressionNode
       return std::string();
     }
 
-    std::string targetName = parameters.front();
+    std::string const& targetName = parameters.front();
     if (targetName.empty() ||
         !cmGeneratorExpression::IsValidTargetName(targetName)) {
       reportError(context, content->GetOriginalExpression(),
@@ -1759,7 +1759,7 @@ static const struct TargetObjectsNode : public cmGeneratorExpressionNode
     const GeneratorExpressionContent* content,
     cmGeneratorExpressionDAGChecker* /*dagChecker*/) const override
   {
-    std::string tgtName = parameters.front();
+    std::string const& tgtName = parameters.front();
     cmGeneratorTarget* gt = context->LG->FindGeneratorTargetToUse(tgtName);
     if (!gt) {
       std::ostringstream e;
@@ -1847,7 +1847,7 @@ static const struct TargetRuntimeDllsNode : public cmGeneratorExpressionNode
     const GeneratorExpressionContent* content,
     cmGeneratorExpressionDAGChecker* /*dagChecker*/) const override
   {
-    std::string tgtName = parameters.front();
+    std::string const& tgtName = parameters.front();
     cmGeneratorTarget* gt = context->LG->FindGeneratorTargetToUse(tgtName);
     if (!gt) {
       std::ostringstream e;
@@ -2396,7 +2396,7 @@ protected:
     cmGeneratorExpressionDAGChecker* dagChecker) const
   {
     // Lookup the referenced target.
-    std::string name = parameters.front();
+    std::string const& name = parameters.front();
 
     if (!cmGeneratorExpression::IsValidTargetName(name)) {
       ::reportError(context, content->GetOriginalExpression(),

Source/cmGetPropertyCommand.cxx

@@ -71,7 +71,7 @@ bool cmGetPropertyCommand(std::vector<std::string> const& args,
   }
 
   // The cmake variable in which to store the result.
-  const std::string variable = args[0];
+  std::string const& variable = args[0];
 
   std::string name;
   std::string propertyName;

Source/cmListCommand.cxx

@@ -1199,7 +1199,7 @@ bool HandleSortCommand(std::vector<std::string> const& args,
   const std::string messageHint = "sub-command SORT ";
 
   while (argumentIndex < args.size()) {
-    const std::string option = args[argumentIndex++];
+    std::string const& option = args[argumentIndex++];
     if (option == "COMPARE") {
       if (sortCompare != cmStringSorter::Compare::UNINITIALIZED) {
         std::string error = cmStrCat(messageHint, "option \"", option,
@@ -1208,7 +1208,7 @@ bool HandleSortCommand(std::vector<std::string> const& args,
         return false;
       }
       if (argumentIndex < args.size()) {
-        const std::string argument = args[argumentIndex++];
+        std::string const& argument = args[argumentIndex++];
         if (argument == "STRING") {
           sortCompare = cmStringSorter::Compare::STRING;
         } else if (argument == "FILE_BASENAME") {
@@ -1235,7 +1235,7 @@ bool HandleSortCommand(std::vector<std::string> const& args,
         return false;
       }
       if (argumentIndex < args.size()) {
-        const std::string argument = args[argumentIndex++];
+        std::string const& argument = args[argumentIndex++];
         if (argument == "SENSITIVE") {
           sortCaseSensitivity = cmStringSorter::CaseSensitivity::SENSITIVE;
         } else if (argument == "INSENSITIVE") {
@@ -1259,7 +1259,7 @@ bool HandleSortCommand(std::vector<std::string> const& args,
         return false;
       }
       if (argumentIndex < args.size()) {
-        const std::string argument = args[argumentIndex++];
+        std::string const& argument = args[argumentIndex++];
         if (argument == "ASCENDING") {
           sortOrder = cmStringSorter::Order::ASCENDING;
         } else if (argument == "DESCENDING") {

Source/cmLoadCacheCommand.cxx

@@ -106,7 +106,7 @@ static bool ReadWithPrefix(std::vector<std::string> const& args,
   }
 
   // Prepare the table of variables to read.
-  std::string const prefix = args[2];
+  std::string const& prefix = args[2];
   std::set<std::string> const variablesToRead(args.begin() + 3, args.end());
 
   // Read the cache file.

Source/cmMathCommand.cxx

@@ -57,10 +57,10 @@ bool HandleExprCommand(std::vector<std::string> const& args,
 
   if (argumentIndex < args.size()) {
     const std::string messageHint = "sub-command EXPR ";
-    const std::string option = args[argumentIndex++];
+    std::string const& option = args[argumentIndex++];
     if (option == "OUTPUT_FORMAT") {
       if (argumentIndex < args.size()) {
-        const std::string argument = args[argumentIndex++];
+        std::string const& argument = args[argumentIndex++];
         if (argument == "DECIMAL") {
           outputFormat = NumericFormat::DECIMAL;
         } else if (argument == "HEXADECIMAL") {