BLD Use Cython's shared memoryview utility to reduce wheel size (scikit-learn#31151)

Co-authored-by: Loïc Estève <[email protected]>

Author: thomasjpfan

sklearn/meson.build

@@ -180,6 +180,8 @@ else:
     check: true
     ).stdout().strip()
 
+cython_program = find_program(cython.cmd_array()[0])
+
 scikit_learn_cython_args = [
   '-X language_level=3', '-X boundscheck=' + boundscheck, '-X wraparound=False',
   '-X initializedcheck=False', '-X nonecheck=False', '-X cdivision=True',
@@ -190,7 +192,25 @@ scikit_learn_cython_args = [
 ]
 cython_args += scikit_learn_cython_args
 
-cython_program = find_program(cython.cmd_array()[0])
+if cython.version().version_compare('>=3.1.0')
+  cython_shared_src = custom_target(
+    install: false,
+    output: '_cyutility.c',
+    command: [
+      cython_program, '-3', '--fast-fail',
+      '--generate-shared=' + meson.current_build_dir()/'_cyutility.c'
+    ],
+  )
+
+  py.extension_module('_cyutility',
+    cython_shared_src,
+    subdir: 'sklearn',
+    cython_args: cython_args,
+    install: true,
+  )
+
+  cython_args += ['--shared=sklearn._cyutility']
+endif
 
 cython_gen = generator(cython_program,
   arguments : cython_args + ['@INPUT@', '--output-file', '@OUTPUT@'],
@@ -202,7 +222,6 @@ cython_gen_cpp = generator(cython_program,
   output : '@[email protected]',
 )
 
-
 # Write file in Meson build dir to be able to figure out from Python code
 # whether scikit-learn was built with Meson. Adapted from pandas
 # _version_meson.py.