GH-45071: [Packaging][Docs] Fix NumPy v2 include directory for Emscripten, and update Pyodide-related documentation

ci/docker/conda-python-emscripten.dockerfile

@@ -27,14 +27,14 @@ ARG required_python_min="(3,12)"
 # fail if python version < 3.12
 RUN echo "check PYTHON>=${required_python_min}" && python -c "import sys;sys.exit(0 if sys.version_info>=${required_python_min} else 1)"
 
-# install selenium and pyodide-build and recent python
+# install selenium and recent pyodide-build and recent python
 
 # needs to be a login shell so ~/.profile is read
 SHELL ["/bin/bash", "--login", "-c", "-o", "pipefail"]
 
 RUN python -m pip install --no-cache-dir selenium==${selenium_version} && \
-    python -m pip install --no-cache-dir --upgrade pyodide-build==${pyodide_version}
-    
+    python -m pip install --no-cache-dir --upgrade pyodide-build>=${pyodide_version}
+
 # install pyodide dist directory to /pyodide
 RUN pyodide_dist_url="https://github.com/pyodide/pyodide/releases/download/${pyodide_version}/pyodide-${pyodide_version}.tar.bz2" && \
     wget -q "${pyodide_dist_url}" -O- | tar -xj -C /

docs/source/developers/cpp/emscripten.rst

@@ -33,7 +33,9 @@ activate it using the commands below (see https://emscripten.org/docs/getting_st
    git clone https://github.com/emscripten-core/emsdk.git
    cd emsdk
    # replace <version> with the desired EMSDK version.
-   # e.g. for Pyodide 0.24, you need EMSDK version 3.1.45
+   # e.g. for Pyodide 0.26, you need EMSDK version 3.1.58
+   # the versions can be found in the Makefile.envs file in the Pyodide repo:
+   # https://github.com/pyodide/pyodide/blob/10b484cfe427e076c929a55dc35cfff01ea8d3bc/Makefile.envs
    ./emsdk install <version>
    ./emsdk activate <version>
    source ./emsdk_env.sh
@@ -46,8 +48,8 @@ versions of emsdk tools.
 .. code:: shell
 
    # install Pyodide build tools.
-   # e.g. for version 0.24 of Pyodide:
-   pip install pyodide-build==0.24
+   # e.g., for version 0.26 of Pyodide, pyodide-build 0.26 and later work
+   pip install "pyodide-build>=0.26"
 
 Then build with the ``ninja-release-emscripten`` CMake preset,
 like below:
@@ -69,8 +71,7 @@ go to ``arrow/python`` and run
    pyodide build
 
 It should make a wheel targeting the currently enabled version of
-Pyodide (i.e. the version corresponding to the currently installed
-``pyodide-build``) in the ``dist`` subdirectory.
+Pyodide in the ``dist`` subdirectory.
 
 
 Manual Build
@@ -85,9 +86,8 @@ you will need to override. In particular you will need:
 
 #. ``CMAKE_TOOLCHAIN_FILE`` set by using ``emcmake cmake`` instead of just ``cmake``.
 
-#. You will quite likely need to set ``ARROW_ENABLE_THREADING`` to ``OFF``
-   for builds targeting single threaded Emscripten environments such as
-   Pyodide.
+#. You will need to set ``ARROW_ENABLE_THREADING`` to ``OFF`` for builds
+   targeting single-threaded Emscripten environments such as Pyodide.
 
 #. ``ARROW_FLIGHT`` and anything else that uses network probably won't
    work.

python/CMakeLists.txt

@@ -166,8 +166,17 @@ if($ENV{PYODIDE})
   # modules (at least under Pyodide it does).
   set(Python3_INCLUDE_DIR $ENV{PYTHONINCLUDE})
   set(Python3_LIBRARY $ENV{CPYTHONLIB})
-  set(Python3_NumPy_INCLUDE_DIR $ENV{NUMPY_LIB}/core/include)
   set(Python3_EXECUTABLE)
+  execute_process(COMMAND ${Python3_EXECUTABLE} -c
+                          "import numpy; print(numpy.__version__)"
+                  OUTPUT_VARIABLE PYODIDE_NUMPY_VERSION
+                  OUTPUT_STRIP_TRAILING_WHITESPACE)
+  string(REGEX MATCH "^([0-9]+)" PYODIDE_NUMPY_MAJOR_VERSION ${PYODIDE_NUMPY_VERSION})
+  if(PYODIDE_NUMPY_MAJOR_VERSION GREATER_EQUAL 2)
+    set(Python3_NumPy_INCLUDE_DIR $ENV{NUMPY_LIB}/_core/include)
+  else()
+    set(Python3_NumPy_INCLUDE_DIR $ENV{NUMPY_LIB}/core/include)
+  endif()
   set(ENV{_PYTHON_SYSCONFIGDATA_NAME} $ENV{SYSCONFIG_NAME})
   # we set the c and cxx compiler manually to bypass pywasmcross
   # which is pyodide's way of messing with C++ build parameters.