[Build] Deprecate builtin_zeromq and builtin_cppzmq build options

The `builtin_zeromq` and `builtin_cppzmq` build options are deprecated
and will be removed in ROOT 6.42. The ZeroMQ library and its Python
bindings are used by the experimental RooFit multiprocessing package,
and the ZeroMQ versions it requires (>=4.3.5) are now readily available
in the package managers (Conda, Homebrew, and newer Linux
distributions).

Author: guitargeek

.github/workflows/root-ci-config/buildconfig/fedora43.txt

@@ -1,10 +1,9 @@
 CMAKE_CXX_STANDARD=23
-builtin_cppzmq=OFF
-builtin_zeromq=OFF
 builtin_zlib=ON
 builtin_zstd=ON
 experimental_adaptivecpp=ON
 pythia8=ON
+roofit_multiprocess=ON
 test_distrdf_dask=OFF
 test_distrdf_pyspark=OFF
 vdt=OFF

.github/workflows/root-ci-config/buildconfig/fedora44.txt

@@ -1,9 +1,8 @@
 CMAKE_CXX_STANDARD=23
-builtin_cppzmq=OFF
-builtin_zeromq=OFF
 builtin_zlib=ON
 builtin_zstd=ON
 experimental_adaptivecpp=ON
 pythia8=ON
+roofit_multiprocess=ON
 test_distrdf_pyspark=OFF
 vdt=OFF

.github/workflows/root-ci-config/buildconfig/global.txt

@@ -6,7 +6,7 @@ asserts=OFF
 builtin_cfitsio=OFF
 builtin_clang=ON
 builtin_cling=ON
-builtin_cppzmq=ON
+builtin_cppzmq=OFF
 builtin_fftw3=OFF
 builtin_freetype=OFF
 builtin_ftgl=OFF
@@ -24,7 +24,7 @@ builtin_unuran=OFF
 builtin_vdt=OFF
 builtin_xrootd=OFF
 builtin_xxhash=OFF
-builtin_zeromq=ON
+builtin_zeromq=OFF
 builtin_zlib=OFF
 builtin_zstd=OFF
 ccache=ON
@@ -67,7 +67,7 @@ pythia8=OFF
 qt6web=OFF
 r=ON
 roofit=ON
-roofit_multiprocess=ON
+roofit_multiprocess=OFF
 root7=ON
 rootbench=OFF
 roottest=ON

.github/workflows/root-ci-config/buildconfig/mac-beta.txt

@@ -1,6 +1,5 @@
 CMAKE_CXX_STANDARD=23
 builtin_cfitsio=ON
-builtin_cppzmq=ON
 builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
@@ -17,7 +16,6 @@ builtin_unuran=ON
 builtin_vdt=ON
 builtin_xrootd=ON
 builtin_xxhash=ON
-builtin_zeromq=ON
 builtin_zstd=ON
 check_connection=ON
 cocoa=ON

.github/workflows/root-ci-config/buildconfig/mac14.txt

@@ -1,7 +1,6 @@
 ROOT_CTEST_CUSTOM_FLAGS="-E ^tutorial-"
 asimage_tiff=OFF
 builtin_cfitsio=ON
-builtin_cppzmq=ON
 builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
@@ -20,7 +19,6 @@ builtin_unuran=ON
 builtin_vdt=ON
 builtin_xrootd=ON
 builtin_xxhash=ON
-builtin_zeromq=ON
 builtin_zstd=ON
 cocoa=ON
 davix=OFF

.github/workflows/root-ci-config/buildconfig/mac15.txt

@@ -1,5 +1,4 @@
 builtin_cfitsio=ON
-builtin_cppzmq=ON
 builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
@@ -16,7 +15,6 @@ builtin_unuran=ON
 builtin_vdt=ON
 builtin_xrootd=ON
 builtin_xxhash=ON
-builtin_zeromq=ON
 builtin_zstd=ON
 cocoa=ON
 davix=OFF

.github/workflows/root-ci-config/buildconfig/mac26.txt

@@ -1,6 +1,5 @@
 CMAKE_CXX_STANDARD=23
 builtin_cfitsio=ON
-builtin_cppzmq=ON
 builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
@@ -17,7 +16,6 @@ builtin_unuran=ON
 builtin_vdt=ON
 builtin_xrootd=ON
 builtin_xxhash=ON
-builtin_zeromq=ON
 builtin_zstd=ON
 check_connection=ON
 cocoa=ON

.github/workflows/root-ci-config/buildconfig/rawhide.txt

@@ -1,9 +1,8 @@
-builtin_cppzmq=OFF
-builtin_zeromq=OFF
 builtin_zlib=ON
 builtin_zstd=ON
 pythia8=ON
 test_distrdf_dask=OFF
 test_distrdf_pyspark=OFF
 tmva-sofie=OFF
 vdt=OFF
+roofit_multiprocess=ON

.github/workflows/root-ci-config/buildconfig/windows10.txt

@@ -25,7 +25,6 @@ minuit2_omp=OFF
 pyroot2=OFF
 pyroot3=ON
 r=OFF
-roofit_multiprocess=OFF
 runtime_cxxmodules=OFF
 ssl=OFF
 test_distrdf_dask=OFF

README/ReleaseNotes/v640/index.md

@@ -43,6 +43,10 @@ The following people have contributed to this new version:
   never had any effect on ROOT. The associated bit TDirectory::fgAddDirectory was deprecated as well. Although users can set and read the bit, its usage should be
   stopped completely to avoid any confusion. The bit and functions will be removed in ROOT 7.
 * The method `RooRealVar::removeRange()` and the corresponding method in `RooErrorVar` have been deprecated because the name was misleading, and they will be removed in ROOT 6.42. Despite the name, the function did not actually remove a range, but only cleared its limits by setting them to  `−inf,+inf` leaving the named range itself defined (so `hasRange()` would still return `true`). Users should now explicitly call `removeMin()` and `removeMax()` to remove the lower and upper limits of a range.
+* The `builtin_zeromq` and `builtin_cppzmq` build options are deprecated and will be removed in ROOT 6.42.
+  The ZeroMQ library and its C++ bindings are used by the experimental RooFit multiprocessing package, enabled by the `roofit_multiprocess` build option.
+  The ZeroMQ versions it requires (>=4.3.6 or 4.3.5 with the draft API) are now available in the package managers of several platforms, for example Conda, Homebrew, Fedora and the Extra Packages for Enterprise Linux (EPEL).
+  The `roofit_multiprocess` feature is only required by a small set of RooFit power uses, who are using one of these environments and therefore don't require the builtin ZeroMQ library.
 
 ## Removals