[RF] Don't use std::to_string for floating point numbers

The `std::to_string` function is not locale-independent, so we should
better not use is for floating point numbers.

Author: guitargeek

roofit/codegen/src/CodegenImpl.cxx

@@ -501,15 +501,16 @@ void codegenImpl(RooParamHistFunc &arg, CodegenContext &ctx)
 {
    std::string const &idx = arg.dataHist().calculateTreeIndexForCodeSquash(ctx, arg.xList());
    std::string arrName = ctx.buildArg(arg.paramList());
-   std::string result = arrName + "[" + idx + "]";
+   std::stringstream result;
+   result << arrName << "[" << idx << "]";
    if (arg.relParam()) {
       // get weight[idx] * binv[idx]. Here we get the bin volume for the first element as we assume the distribution to
       // be binned uniformly.
       double binV = arg.dataHist().binVolume(0);
       std::string weightArr = arg.dataHist().declWeightArrayForCodeSquash(ctx, false);
-      result += " * *(" + weightArr + " + " + idx + ") * " + std::to_string(binV);
+      result << " * *(" << weightArr << " + " << idx + ") * " << binV;
    }
-   ctx.addResult(&arg, result);
+   ctx.addResult(&arg, result.str());
 }
 
 void codegenImpl(RooPoisson &arg, CodegenContext &ctx)
@@ -812,7 +813,9 @@ std::string rooHistIntegralTranslateImpl(int code, RooAbsArg const &arg, RooData
                                     << std::endl;
       return "";
    }
-   return std::to_string(dataHist.sum(histFuncMode));
+   std::stringstream ss;
+   ss << dataHist.sum(histFuncMode);
+   return ss.str();
 }
 
 } // namespace
@@ -853,7 +856,9 @@ std::string codegenIntegralImpl(RooMultiVarGaussian &arg, int code, const char *
       throw std::runtime_error(errorMsg.str().c_str());
    }
 
-   return std::to_string(arg.analyticalIntegral(code, rangeName));
+   std::stringstream ss;
+   ss << arg.analyticalIntegral(code, rangeName);
+   return ss.str();
 }
 
 std::string codegenIntegralImpl(RooPoisson &arg, int code, const char *rangeName, CodegenContext &ctx)

roofit/jsoninterface/src/JSONParser.cxx

@@ -29,9 +29,9 @@ inline nlohmann::json parseWrapper(std::istream &is)
 
 // TJSONTree methods
 
-TJSONTree::TJSONTree() : root(this){};
+TJSONTree::TJSONTree() : root(this) {};
 
-TJSONTree::TJSONTree(std::istream &is) : root(this, is){};
+TJSONTree::TJSONTree(std::istream &is) : root(this, is) {};
 
 TJSONTree::~TJSONTree()
 {
@@ -248,7 +248,11 @@ std::string TJSONTree::Node::val() const
    case nlohmann::json::value_t::boolean: return node->get().get<bool>() ? "true" : "false";
    case nlohmann::json::value_t::number_integer: return std::to_string(node->get().get<int>());
    case nlohmann::json::value_t::number_unsigned: return std::to_string(node->get().get<unsigned int>());
-   case nlohmann::json::value_t::number_float: return std::to_string(node->get().get<double>());
+   case nlohmann::json::value_t::number_float: {
+      std::stringstream ss;
+      ss << node->get().get<double>();
+      return ss.str();
+   }
    default:
       throw std::runtime_error("node \"" + node->key() + "\": implicit string conversion for type " +
                                node->get().type_name() + " not supported!");
@@ -321,9 +325,12 @@ using const_json_iterator = nlohmann::basic_json<>::const_iterator;
 template <class Nd, class NdType, class json_it>
 class TJSONTree::Node::ChildItImpl final : public RooFit::Detail::JSONNode::child_iterator_t<Nd>::Impl {
 public:
-   enum class POS { BEGIN, END };
+   enum class POS {
+      BEGIN,
+      END
+   };
    ChildItImpl(NdType &n, POS p)
-      : node(n), iter(p == POS::BEGIN ? n.get_node().get().begin() : n.get_node().get().end()){};
+      : node(n), iter(p == POS::BEGIN ? n.get_node().get().begin() : n.get_node().get().end()) {};
    ChildItImpl(NdType &n, json_it it) : node(n), iter(it) {}
    ChildItImpl(const ChildItImpl &other) : node(other.node), iter(other.iter) {}
    using child_iterator = RooFit::Detail::JSONNode::child_iterator_t<Nd>;

roofit/roofitcore/inc/RooFit/CodegenContext.h

@@ -223,10 +223,12 @@ std::string CodegenContext::buildArgSpanImpl(std::span<const T> arr)
 {
    unsigned int n = arr.size();
    std::string arrName = getTmpVarName();
-   std::string arrDecl = typeName<T>() + " " + arrName + "[" + std::to_string(n) + "] = {";
+   std::stringstream ss;
+   ss << typeName<T>() << " " << arrName << "[" << n << "] = {";
    for (unsigned int i = 0; i < n; i++) {
-      arrDecl += " " + std::to_string(arr[i]) + ",";
+      ss << " " << arr[i] << ",";
    }
+   std::string arrDecl = ss.str();
    arrDecl.back() = '}';
    arrDecl += ";\n";
    addToCodeBody(arrDecl, true);

roofit/roofitcore/src/RooAbsArg.cxx

@@ -1970,12 +1970,14 @@ void RooAbsArg::graphVizTree(std::ostream &os, const char *delimiter, bool useTi
       std::string typeFormat = "\\texttt{";
       std::string nodeType = (useLatex) ? typeFormat + node->ClassName() + "}" : node->ClassName();
 
+      os << "\"" << nodeName << "\" [ color=" << (node->isFundamental() ? "blue" : "red") << ", label=\"" << nodeType
+         << delimiter << nodeLabel;
+
       if (auto realNode = dynamic_cast<RooAbsReal *>(node)) {
-         nodeLabel += delimiter + std::to_string(realNode->getVal());
+         os << delimiter << realNode->getVal();
       }
 
-      os << "\"" << nodeName << "\" [ color=" << (node->isFundamental() ? "blue" : "red") << ", label=\"" << nodeType
-         << delimiter << nodeLabel << "\"];" << std::endl;
+      os << "\"];" << std::endl;
    }
 
    // Get set of all server links

roofit/roofitcore/test/testRooProdPdf.cxx

@@ -83,13 +83,13 @@ TEST(RooProdPdf, TestGetPartIntList)
 
    RooWorkspace ws;
 
-   double a = 10.;
-   double b = 4.;
-   double c = 2.5;
+   auto &x = static_cast<RooRealVar &>(*ws.factory("x[0, 0, 10.]"));
+   auto &y = static_cast<RooRealVar &>(*ws.factory("y[0, 0, 4.]"));
+   auto &z = static_cast<RooRealVar &>(*ws.factory("z[0, 0, 2.5]"));
 
-   auto &x = static_cast<RooRealVar &>(*ws.factory("x[0, 0, " + std::to_string(a) + "]"));
-   auto &y = static_cast<RooRealVar &>(*ws.factory("y[0, 0, " + std::to_string(b) + "]"));
-   auto &z = static_cast<RooRealVar &>(*ws.factory("z[0, 0, " + std::to_string(c) + "]"));
+   double a = x.getMax();
+   double b = y.getMax();
+   double c = z.getMax();
 
    // Factorize the product in one 1D and one 2D pdf to get a more complicated
    // and complete test case.

roofit/roofitcore/test/testRooRombergIntegrator.cxx

@@ -112,7 +112,9 @@ void testConvergenceSettings(const RooFormulaVar &formula, const RooArgSet &obse
    SCOPED_TRACE(std::string("Function to integrate: ") + name + "\t" + formula.GetTitle());
 
    for (double relEps : {1.E-3, 1.E-6, 1.E-8}) {
-      SCOPED_TRACE(std::string("relEps=" + std::to_string(relEps)));
+      std::stringstream traceName;
+      traceName << "relEps=" << relEps;
+      SCOPED_TRACE(traceName.str());
       TStopwatch stopNew;
       TStopwatch stopRoot;
 
@@ -300,9 +302,9 @@ TEST(RooIntegrator1D, RunErf_NStep)
       const double min = limits.first;
       const double max = limits.second;
       RooRealVar theX("theX", "x", min, max);
-      std::string funcStr =
-         std::string("ROOT::Math::gaussian_pdf(theX, ") + std::to_string(sigma) + ", " + std::to_string(mean) + ")";
-      RooFormulaVar gaus("gaus", funcStr.c_str(), theX);
+      std::stringstream funcStr;
+      funcStr << "ROOT::Math::gaussian_pdf(theX, " << sigma << ", " << mean << ")";
+      RooFormulaVar gaus("gaus", funcStr.str().c_str(), theX);
       RooRealBinding binding(gaus, theX);
 
       double targetError = 0.;