[build] Migrate build backend to scikit-build-core

Author: jase231

bindings/pyroot/pythonizations/python/ROOT/__init__.py

@@ -18,6 +18,7 @@
 import types
 from importlib.abc import Loader, MetaPathFinder
 from importlib.machinery import ModuleSpec
+from importlib.metadata import PackageNotFoundError, version
 
 from . import _asan  # noqa: F401  # imported for side effects for setup specific to AddressSanitizer environments
 from ._facade import ROOTFacade
@@ -190,6 +191,28 @@ def find_spec(self, fullname: str, path, target=None) -> ModuleSpec:
 
         # from . import JsMVA
 
+# importlib.metadata.version reads distribution metadata from the package's
+# .dist-info folder, which is typically generated by the package manager.
+# An installed ROOT wheel distribution will contain this metadata,
+# and version("ROOT") will succeed. However, ROOT built or installed
+# through any other channel (e.g. from source) has no .dist-info folder,
+# so the corresponding metadata is missing, therefore version("ROOT") raises
+# PackageNotFoundError, despite `import ROOT` succeeding in the same environment.
+# See: https://docs.python.org/3/library/importlib.metadata.html
+try:
+    if "a" in version("ROOT"):
+        import warnings
+
+        warnings.warn(
+            "This distribution of ROOT is in alpha stage. Feedback is welcome and appreciated. "
+            "Feel free to reach out to the user forum for questions and general feedback at "
+            "https://github.com/root-project/root/issues. "
+            "Do not rely on this distribution for production purposes.",
+            stacklevel=2,  # emit the warning in the caller
+        )
+except PackageNotFoundError:
+    pass
+
 
 def _cleanup():
     # Delete TBrowser instances while the GUI event loop is still alive,

pyproject.toml

@@ -1,8 +1,9 @@
 [build-system]
-requires = ["cmake", "setuptools<72", "wheel", "numpy"]
+requires = ["scikit-build-core>=0.10"]
+build-backend = "scikit_build_core.build"
 
 [project]
-name = "ROOT"
+name = "root"
 version = "0.1a12"
 requires-python = ">=3.10"
 maintainers = [
@@ -15,16 +16,73 @@ dependencies = [
   "numpy",
 ]
 
-# Demonstrate how to expose ROOT CLI tools the Python way. For now only include
-# `root`, other tools can be added later using the same approach.
+# Point backend to python packages and to explicitly use Ninja
+[tool.scikit-build]
+wheel.packages = [
+	"bindings/pyroot/pythonizations/python/ROOT",
+	"bindings/pyroot/cppyy/cppyy/python/cppyy",
+]
+cmake.args = [
+	"-GNinja", 
+]
+
+[tool.scikit-build.cmake.define]
+# CMake install directories
+CMAKE_INSTALL_BINDIR = "ROOT/bin"
+CMAKE_INSTALL_CMAKEDIR = "ROOT/cmake"
+CMAKE_INSTALL_FONTDIR = "ROOT/fonts"
+CMAKE_INSTALL_ICONDIR = "ROOT/icons"
+CMAKE_INSTALL_INCLUDEDIR = "ROOT/include"
+CMAKE_INSTALL_LIBDIR = "ROOT/lib"
+CMAKE_INSTALL_MACRODIR = "ROOT/macros"
+CMAKE_INSTALL_MANDIR = "ROOT/man"
+CMAKE_INSTALL_PYTHONDIR = "."
+CMAKE_INSTALL_SYSCONFDIR = "ROOT/etc"
+CMAKE_INSTALL_TUTDIR = "ROOT/tutorials"
+
+# Generic minimal build config
+gminimal="ON"
+asimage="ON"
+opengl="OFF"
+runtime_cxxmodules="ON"
+fail-on-missing="ON"
+
+# Explicitly list components that gminimal implicitly turns off as documentation
+# tmva-pymva and tpython are disabled for manylinux compatibility
+# see https://peps.python.org/pep-0513/#libpythonx-y-so-1 
+tmva-pymva="OFF"
+tpython="OFF"
+thisroot_scripts="OFF" # the thisroot.* scripts are broken if CMAKE_INSTALL_PYTHONDIR!=CMAKE_INSTALL_LIBDIR
+
+# Builtins
+builtin_nlohmannjson="ON"
+builtin_tbb="ON"
+builtin_xrootd="ON"
+builtin_tiff="ON"
+builtin_lz4="ON"
+builtin_fftw3="ON"
+builtin_gsl="ON"
+builtin_lzma="ON"
+builtin_zstd="ON"
+builtin_xxhash="ON"
+pyroot="ON"
+dataframe="ON"
+xrootd="ON"
+ssl="ON"
+imt="ON"
+roofit="ON"
+mathmore="ON"
+
+# Expose the ROOT cli as an executable command via _rootcli wrapper 
 [project.scripts]
 root = "ROOT._rootcli:main"
 
 [tool.cibuildwheel]
-# Increase pip debugging output
+build-frontend = { name = "build" }
 build-verbosity = 1
 manylinux-x86_64-image = "manylinux_2_28"
 
 # Install system libraries
 [tool.cibuildwheel.linux]
 before-all = "dnf install -y epel-release && /usr/bin/crb enable && dnf install -y openssl-devel libX11-devel libXpm-devel libXft-devel libXext-devel libuuid-devel libjpeg-devel giflib-devel libtiff-devel"
+