[CMake] Always build Minuit2

In the discussion thread to JIRA ticket ROOT-10864, Axel suggested the
removal of the option to disable minuit2 as a possible solution.

I think this is a very good idea good idea, because:

  * Minuit2 only depends on `Hist` and `MathCore` anyway.

  * Now that Minuit2 is the default for *all* minimization in ROOT,
    building ROOT without Minuit2 changes the behavior of ROOT way too
    much, in a ways that people that set `minuit2=OFF` probably are not
    intending or aware of.

This closes the following JIRA ticket:
https://sft.its.cern.ch/jira/browse/ROOT-10864

Author: guitargeek

cmake/modules/RootBuildOptions.cmake

@@ -141,7 +141,7 @@ ROOT_BUILD_OPTION(libcxx OFF "Build using libc++")
 ROOT_BUILD_OPTION(macos_native OFF "Disable looking for libraries, includes and binaries in locations other than a native installation (MacOS only)")
 ROOT_BUILD_OPTION(mathmore OFF "Build libMathMore extended math library (requires GSL) [GPL]")
 ROOT_BUILD_OPTION(memory_termination OFF "Free internal ROOT memory before process termination (experimental, used for leak checking)")
-ROOT_BUILD_OPTION(minuit2 ON "Build Minuit2 minimization library")
+ROOT_BUILD_OPTION(minuit2 IGNORE "Build Minuit2 minimization library (deprecated, Minuit2 is always built)")
 ROOT_BUILD_OPTION(minuit2_mpi OFF "Enable support for MPI in Minuit2")
 ROOT_BUILD_OPTION(minuit2_omp OFF "Enable support for OpenMP in Minuit2")
 ROOT_BUILD_OPTION(mpi OFF "Enable support for Message Passing Interface (MPI)")
@@ -239,7 +239,6 @@ if(all)
  set(fcgi_defvalue ON)
  set(imt_defvalue ON)
  set(mathmore_defvalue ON)
- set(minuit2_defvalue ON)
  set(monalisa_defvalue ON)
  set(mysql_defvalue ON)
  set(odbc_defvalue ON)
@@ -372,12 +371,6 @@ endif()
 #---Define at moment the options with the selected default values------------------------------
 ROOT_APPLY_OPTIONS()
 
-# RooFit multiprocess only works with Minuit2. In fact, it depends on it at build time.
-if(roofit_multiprocess AND NOT minuit2)
-    message(WARNING "Option 'roofit_multiprocess' requires option `minuit2`. We're setting `minuit2=ON` for you. Consider setting `minuit2=ON` yourself to silence this warning.")
-    set(minuit2 ON CACHE BOOL "" FORCE)
-endif()
-
 #---roottest option implies testing
 if(roottest OR rootbench)
   set(testing ON CACHE BOOL "" FORCE)
@@ -419,7 +412,7 @@ foreach(opt afdsmgrd afs alien bonjour castor chirp cxx11 cxx14 cxx17 geocad gfa
 endforeach()
 
 #---Deprecated options------------------------------------------------------------------------
-foreach(opt cxxmodules exceptions oracle pythia6 pythia6_nolink pyroot-python2)
+foreach(opt cxxmodules exceptions oracle pythia6 pythia6_nolink pyroot-python2 minuit2)
   if(${opt})
     message(DEPRECATION ">>> Option '${opt}' is deprecated and will be removed in the next release of ROOT. Please contact [email protected] should you still need it.")
   endif()

cmake/modules/RootConfiguration.cmake

@@ -301,7 +301,6 @@ set(gslflags)
 set(shadowpw ${value${shadowpw}})
 set(buildmathmore ${value${mathmore}})
 set(buildroofit ${value${roofit}})
-set(buildminuit2 ${value${minuit2}})
 set(buildunuran ${value${unuran}})
 set(buildgdml ${value${gdml}})
 set(buildhttp ${value${http}})

math/CMakeLists.txt

@@ -10,9 +10,7 @@ if(mathmore)
 endif()
 add_subdirectory(matrix)
 add_subdirectory(minuit)
-if(minuit2)
-  add_subdirectory(minuit2)
-endif()
+add_subdirectory(minuit2)
 add_subdirectory(fumili)
 add_subdirectory(physics)
 add_subdirectory(mlp)

math/mathcore/CMakeLists.txt

@@ -212,10 +212,6 @@ foreach(incl ${math_incl})
    target_include_directories(MathCore PUBLIC $<BUILD_INTERFACE:${incl}>)
 endforeach()
 
-if(NOT minuit2)
-    target_compile_definitions(MathCore PRIVATE MATH_USE_LEGACY_MINUIT_AS_DEFAULT)
-endif()
-
 target_compile_definitions(MathCore INTERFACE ${VecCore_DEFINITIONS})
 target_link_libraries(MathCore PRIVATE ${CMAKE_THREAD_LIBS_INIT})
 

math/mathcore/src/MinimizerOptions.cxx

@@ -104,12 +104,7 @@ const std::string & MinimizerOptions::DefaultMinimizerType()
 
 
    // The "default default" minimizer in case there is nothing set in .rootrc
-#ifndef MATH_USE_LEGACY_MINUIT_AS_DEFAULT
    static constexpr auto defaultDefaultMinimizer = "Minuit2";
-#else
-   static constexpr auto defaultDefaultMinimizer = "Minuit";
-#endif // MATH_USE_LEGACY_MINUIT_AS_DEFAULT
-
 
 #ifdef MATH_NO_PLUGIN_MANAGER
    if (Minim::gDefaultMinimizer.size() != 0)

math/mathcore/test/CMakeLists.txt

@@ -6,7 +6,7 @@
 
 project(mathcore-tests)
 
-set(Libraries Core RIO Net Hist Graf Graf3d Gpad Tree
+set(Libraries Core RIO Net Hist Graf Graf3d Gpad Tree Minuit2
               Rint Postscript Matrix Physics MathCore Thread)
 
 set(TestSource
@@ -32,23 +32,19 @@ set(TestSource
     testIntegrationMultiDim.cxx
     testAnalyticalIntegrals.cxx
     testTStatistic.cxx
-    fit/testFit.cxx
-    fit/testGraphFit.cxx
     fit/SparseDataComparer.cxx
-    fit/SparseFit4.cxx
     fit/SparseFit3.cxx
+    fit/SparseFit4.cxx
     fit/testBinnedFitExecPolicy.cxx
-    fit/testLogLExecPolicy.cxx )
+    fit/testFit.cxx
+    fit/testGraphFit.cxx
+    fit/testLogLExecPolicy.cxx
+    fit/testMinim.cxx)
 
 if(mathmore)
   list(APPEND Libraries MathMore)
 endif()
 
-if(minuit2)
-  list(APPEND TestSource fit/testMinim.cxx)
-  list(APPEND Libraries Minuit2)
-endif()
-
 if(r)
  add_definitions(-DROOT_HAS_R)
  list(APPEND Libraries RInterface)

roofit/roostats/test/CMakeLists.txt

@@ -20,6 +20,4 @@ endif()
 if(roofit_legacy_eval_backend AND minuit2)
   ROOT_ADD_TEST(test-stressroostats-legacy-minuit2 COMMAND stressRooStats -minim Minuit2 -b legacy FAILREGEX "FAILED|Error in" LABELS longtest)
 endif()
-if(minuit2)
-  ROOT_ADD_TEST(test-stressroostats-cpu-minuit2 COMMAND stressRooStats -minim Minuit2 -b cpu FAILREGEX "FAILED|Error in" LABELS longtest)
-endif()
+ROOT_ADD_TEST(test-stressroostats-cpu-minuit2 COMMAND stressRooStats -minim Minuit2 -b cpu FAILREGEX "FAILED|Error in" LABELS longtest)

tutorials/CMakeLists.txt

@@ -64,14 +64,6 @@ function(ROOT_ADD_TUTORIAL macrofile rc)
 endfunction()
 
 #---Tutorials disabled depending on the build components-------------
-if(NOT ROOT_minuit2_FOUND)
-  set(minuit2_veto fit/fit2dHist.C fit/fitCircle.C
-                   fit/minuit2FitBench2D.C fit/minuit2FitBench.C
-                   fit/minuit2GausFit.C fit/NumericalMinimization.C
-                   fit/combinedFit.C fit/TestBinomial.C
-                   fit/fitNormSum.C fit/vectorizedFit.C
-                   tutorials/roostats/rs_bernsteinCorrection.C)
-endif()
 
 if(NOT clad)
   set(clad_veto fit/minuit2GausFit.C)
@@ -442,7 +434,6 @@ set(all_veto hsimple.C
              ${extra_veto}
              ${gdml_veto}
              ${gui_veto}
-             ${minuit2_veto}
              ${roofit_veto}
              ${unuran_veto}
              ${xml_veto}