BLD: bump minimum Meson version to 1.5.0

This is needed for the dependency fix in the previous commit,
and it also allows some further cleanup since `custom_target` and
`generator` now allow passing in a `CustomTargetIndex`.

Author: rgommers

.github/workflows/windows_intel_oneAPI.yml

@@ -57,7 +57,7 @@ jobs:
 
       - name: Install packages from conda
         run: |
-          conda install -c conda-forge pkg-config meson=1.4.0 meson-python=0.16.0 ninja openblas libblas=*=*openblas numpy==2.0 cython pybind11 pytest pytest-xdist pytest-timeout pytest-fail-slow pooch rich-click click doit pydevtool hypothesis
+          conda install -c conda-forge pkg-config meson meson-python ninja openblas libblas=*=*openblas numpy==2.0 cython pybind11 pytest pytest-xdist pytest-timeout pytest-fail-slow pooch rich-click click doit pydevtool hypothesis
 
       - name: cache install
         id: cache-install

meson.build

@@ -6,7 +6,7 @@ project(
   # tools/version_utils.py
   version: '1.15.0.dev0',
   license: 'BSD-3',
-  meson_version: '>= 1.1.0',
+  meson_version: '>= 1.5.0',
   default_options: [
     'buildtype=debugoptimized',
     'b_ndebug=if-release',

scipy/_build_utils/echo.py

@@ -25,18 +25,7 @@ cython_linalg = custom_target('cython_linalg',
   install_dir: py3.get_install_dir() / 'scipy/linalg',
   install_tag: 'devel'
 )
-
-# This dummy custom target is only needed to establish a dependency on
-# cython_linalg in a generator below. Adding that dependency directly yields
-# warnings about multiple outputs. And using `depends: cython_linalg[2]` does
-# not work, because that generator depends does not accept CustomTargetIndex,
-# only CustomTarget. See https://github.com/mesonbuild/meson/issues/9837
-_echo = find_program('../_build_utils/echo.py')
-cython_blas_pxd = custom_target(
-  output: '_dummy_cython_blas.pxd',
-  input: cython_linalg[2],
-  command: [_echo, '@INPUT@'],
-)
+cython_blas_pxd = cython_linalg[2]
 
 # pyx -> c, pyx -> cpp generators, depending on __init__.py here.
 linalg_init_cython_gen = generator(cython,
@@ -284,6 +273,8 @@ py3.install_sources(
 #  cython_linalg[2],  # cython_blas.pxd
 #  cython_linalg[3],  # cython_lapack.pxd
 #]
+#py.install_sources(pxd_files)
+
 #custom_target('cython_blas_lapack_pxd',
 #  input : pxd_files,
 #  output : ['cython_blas2.pxd', 'cython_lapack2.pxd'],