[math] Use std::function in ROOT::Math::ParamFunctor

README/ReleaseNotes/v642/index.md

@@ -64,6 +64,7 @@ Users are encouraged to export their models to ONNX and use the retained ONNX pa
 * The **RooStats::DebuggingSampler** and **RooStats::DebuggingTestStat** classes are removed. They were mock implementations of the `TestStatSampler` and `TestStatistic` interfaces that returned uniform random numbers independent of the data, only meant for debugging the RooStats framework itself during its initial development.
 * The `RooTrace` class is deprecated and will be removed in ROOT 6.44. It was a RooFit-specific memory tracer whose instrumentation hooks are compiled out by default, so it has been inert and untested for years. For memory debugging, please use general-purpose tools such as AddressSanitizer or Valgrind instead.
 * Support for the AIX operating system has been removed from the codebase. This support has not been tested since the late v5 releases and the LLVM JIT is not yet supporting AIX.
+* The `ROOT::Math::ParamFunctionBase`, `ROOT::Math::ParamFunctorHandler` and `ROOT::Math::ParamMemFunHandler` classes in `Math/ParamFunctor.h` are removed, together with the `ParamFunctor::GetImpl()` and `ParamFunctor::SetFunction()` methods that exposed them. They implemented the type erasure that `ParamFunctor` now gets from `std::function`, mirroring what was already done for `ROOT::Math::Functor`. Constructing and calling a `ParamFunctor` is unchanged.
 
 ## Build System
 

hist/hist/src/TEfficiency.cxx

@@ -7,6 +7,7 @@
 #include <cmath>
 #include <cstdlib>
 #include <cassert>
+#include <ostream>
 
 //ROOT headers
 #include "Math/DistFuncMathCore.h"

hist/hist/src/TF12.cxx

@@ -13,6 +13,7 @@
 #include "TH1.h"
 #include "TVirtualPad.h"
 
+#include <ostream>
 
 /** \class TF12
     \ingroup Functions

hist/hist/test/test_tkde.cxx

@@ -10,6 +10,7 @@
 #include "TH1.h"
 #include "Math/DistFuncMathCore.h"
 
+#include <iostream>
 
 struct TestKDE {