py-numpy package: enable build on Windows (#43686)

* Add conflicts for some blas implementations that don't build on
  Windows (or with %msvc)
* Need to enclose CC/CXX variables in quotes in case those paths
  have spaces, otherwise Meson runs into errors
* On Windows, Python dependencies now add <prefix>/Scripts to the
  PATH (this is established as a standard in PEP 370)

var/spack/repos/builtin/packages/armpl-gcc/package.py

@@ -319,6 +319,8 @@ class ArmplGcc(Package):
     conflicts("%gcc@:7", when="@22.0.1_gcc-8.2")
     conflicts("%gcc@:6", when="@22.0.1_gcc-7.5")
 
+    conflicts("%msvc", msg="Not compatible with MSVC compiler.")
+
     variant("ilp64", default=False, description="use ilp64 specific Armpl library")
     variant("shared", default=True, description="enable shared libs")
     variant(

var/spack/repos/builtin/packages/atlas/package.py

@@ -61,6 +61,12 @@ class Atlas(Package):
         description="Number of threads to tune to, " "-1 for autodetect, 0 for no threading",
     )
 
+    conflicts(
+        "platform=windows",
+        msg="Atlas requires cygwin to build on Windows, which is unsupported by Spack. "
+        "See https://math-atlas.sourceforge.net/atlas_install/node55.html",
+    )
+
     provides("blas")
     provides("lapack")
     provides("lapack@3.6.1")

var/spack/repos/builtin/packages/cray-libsci/package.py

@@ -25,6 +25,9 @@ class CrayLibsci(Package):
     version("16.06.1")
     version("16.03.1")
 
+    conflicts("platform=windows")
+    conflicts("platform=darwin")
+
     variant("shared", default=True, description="enable shared libs")
     variant("openmp", default=False, description="link with openmp")
     variant("mpi", default=False, description="link with mpi libs")

var/spack/repos/builtin/packages/meson/package.py

@@ -2,8 +2,6 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-
 from spack.package import *
 
 

var/spack/repos/builtin/packages/py-numpy/package.py

@@ -394,9 +394,14 @@ def set_blas_lapack(self):
 
     @when("@1.26:")
     def setup_build_environment(self, env):
-        # https://github.com/scipy/scipy/issues/19357
         if self.spec.satisfies("%apple-clang@15:"):
+            # https://github.com/scipy/scipy/issues/19357
             env.append_flags("LDFLAGS", "-Wl,-ld_classic")
+        elif self.spec.satisfies("%msvc"):
+            # For meson build system, compiler paths must be in quotes
+            # to prevent paths from being split by spaces.
+            env.set("CC", f'"{self.compiler.cc}"')
+            env.set("CXX", f'"{self.compiler.cxx}"')
 
     @when("@:1.25")
     def setup_build_environment(self, env):

var/spack/repos/builtin/packages/python/package.py

@@ -1191,6 +1191,11 @@ def setup_dependent_build_environment(self, env, dependent_spec):
             for directory in {self.platlib, self.purelib}:
                 env.prepend_path("PYTHONPATH", os.path.join(prefix, directory))
 
+            if self.spec.satisfies("platform=windows"):
+                prefix_scripts_dir = prefix.Scripts
+                if os.path.exists(prefix_scripts_dir):
+                    env.prepend_path("PATH", prefix_scripts_dir)
+
         # We need to make sure that the extensions are compiled and linked with
         # the Spack wrapper. Paths to the executables that are used for these
         # operations are normally taken from the sysconfigdata file, which we