windows: use `sys.platform == "win32"` instead of `is_windows` (#35640)

`mypy` only understands `sys.platform == "win32"`, not indirect assignments of that
value to things like `is_windows`. If we don't use the accepted platform checks, `mypy`
registers many Windows-only symbols as not present on Linux, when it should skip the
checks for platform-specific code.

7 files changed, 39 insertions, 49 deletions

diff --git a/var/spack/repos/builtin.mock/packages/cmake/package.py b/var/spack/repos/builtin.mock/packages/cmake/package.py
index 19c1a6f1c1..82e9c073d3 100644
--- a/var/spack/repos/builtin.mock/packages/cmake/package.py
+++ b/var/spack/repos/builtin.mock/packages/cmake/package.py
@@ -8,8 +8,6 @@ import sys
 
 from spack.package import *
 
-is_windows = sys.platform == "win32"
-
 
 def check(condition, msg):
     """Raise an install error if condition is False."""
@@ -59,7 +57,7 @@ class Cmake(Package):
             os.environ["for_install"] == "for_install",
             "Couldn't read env var set in compile envieonmnt",
         )
-        cmake_exe_ext = ".exe" if is_windows else ""
+        cmake_exe_ext = ".exe" if sys.platform == "win32" else ""
         cmake_exe = join_path(prefix.bin, "cmake{}".format(cmake_exe_ext))
         touch(cmake_exe)
         set_executable(cmake_exe)
diff --git a/var/spack/repos/builtin/packages/cmake/package.py b/var/spack/repos/builtin/packages/cmake/package.py
index da0f3c16b5..368c71965b 100644
--- a/var/spack/repos/builtin/packages/cmake/package.py
+++ b/var/spack/repos/builtin/packages/cmake/package.py
@@ -10,8 +10,6 @@ import sys
 import spack.build_environment
 from spack.package import *
 
-is_windows = sys.platform == "win32"
-
 
 class Cmake(Package):
     """A cross-platform, open-source build system. CMake is a family of
@@ -187,7 +185,11 @@ class Cmake(Package):
         default=False,
         description="Enables the generation of html and man page documentation",
     )
-    variant("ncurses", default=not is_windows, description="Enables the build of the ncurses gui")
+    variant(
+        "ncurses",
+        default=sys.platform != "win32",
+        description="Enables the build of the ncurses gui",
+    )
 
     # See https://gitlab.kitware.com/cmake/cmake/-/issues/21135
     conflicts(
diff --git a/var/spack/repos/builtin/packages/perl/package.py b/var/spack/repos/builtin/packages/perl/package.py
index 429530d564..a0f534b74d 100644
--- a/var/spack/repos/builtin/packages/perl/package.py
+++ b/var/spack/repos/builtin/packages/perl/package.py
@@ -23,8 +23,6 @@ from llnl.util.symlink import symlink
 from spack.operating_systems.mac_os import macos_version
 from spack.package import *
 
-is_windows = sys.platform == "win32"
-
 
 class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
     """Perl 5 is a highly capable, feature-rich programming language with over
@@ -76,7 +74,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
 
     extendable = True
 
-    if not is_windows:
+    if sys.platform != "win32":
         depends_on("gdbm@:1.23")
         # Bind us below gdbm-1.20 due to API change: https://github.com/Perl/perl5/issues/18915
         depends_on("gdbm@:1.19", when="@:5.35")
@@ -277,13 +275,13 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
         return config_args
 
     def configure(self, spec, prefix):
-        if is_windows:
+        if sys.platform == "win32":
             return
         configure = Executable("./Configure")
         configure(*self.configure_args())
 
     def build(self, spec, prefix):
-        if is_windows:
+        if sys.platform == "win32":
             pass
         else:
             make()
@@ -291,7 +289,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
     @run_after("build")
     @on_package_attributes(run_tests=True)
     def build_test(self):
-        if is_windows:
+        if sys.platform == "win32":
             win32_dir = os.path.join(self.stage.source_path, "win32")
             with working_dir(win32_dir):
                 nmake("test", ignore_quotes=True)
@@ -299,7 +297,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
             make("test")
 
     def install(self, spec, prefix):
-        if is_windows:
+        if sys.platform == "win32":
             win32_dir = os.path.join(self.stage.source_path, "win32")
             with working_dir(win32_dir):
                 nmake("install", *self.nmake_arguments, ignore_quotes=True)
@@ -308,7 +306,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
 
     @run_after("install")
     def symlink_windows(self):
-        if not is_windows:
+        if sys.platform != "win32":
             return
         win_install_path = os.path.join(self.prefix.bin, "MSWin32")
         if self.is_64bit():
@@ -331,7 +329,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
         spec = self.spec
         maker = make
         cpan_dir = join_path("cpanm", "cpanm")
-        if is_windows:
+        if sys.platform == "win32":
             maker = nmake
             cpan_dir = join_path(self.stage.source_path, cpan_dir)
         if "+cpanm" in spec:
@@ -352,7 +350,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
         if perl_lib_dirs:
             perl_lib_path = ":".join(perl_lib_dirs)
             env.prepend_path("PERL5LIB", perl_lib_path)
-        if is_windows:
+        if sys.platform == "win32":
             env.append_path("PATH", self.prefix.bin)
 
     def setup_dependent_build_environment(self, env, dependent_spec):
@@ -382,7 +380,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
             mkdirp(module.perl_lib_dir)
 
     def setup_build_environment(self, env):
-        if is_windows:
+        if sys.platform == "win32":
             env.append_path("PATH", self.prefix.bin)
             return
 
@@ -410,7 +408,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
         frustrates filter_file on some filesystems (NFSv4), so make them
         temporarily writable.
         """
-        if is_windows:
+        if sys.platform == "win32":
             return
         kwargs = {"ignore_absent": True, "backup": False, "string": False}
 
@@ -478,7 +476,7 @@ class Perl(Package):  # Perl doesn't use Autotools, it should subclass Package
         """
         for ver in ("", self.spec.version):
             ext = ""
-            if is_windows:
+            if sys.platform == "win32":
                 ext = ".exe"
             path = os.path.join(self.prefix.bin, "{0}{1}{2}".format(self.spec.name, ver, ext))
             if os.path.exists(path):
diff --git a/var/spack/repos/builtin/packages/python/package.py b/var/spack/repos/builtin/packages/python/package.py
index e52e5bc87a..747c5cd6e6 100644
--- a/var/spack/repos/builtin/packages/python/package.py
+++ b/var/spack/repos/builtin/packages/python/package.py
@@ -22,8 +22,6 @@ from spack.package import *
 from spack.util.environment import is_system_path
 from spack.util.prefix import Prefix
 
-is_windows = sys.platform == "win32"
-
 
 class Python(Package):
     """The Python programming language."""
@@ -125,12 +123,12 @@ class Python(Package):
     # See https://legacy.python.org/dev/peps/pep-0394/
     variant(
         "pythoncmd",
-        default=not is_windows,
+        default=sys.platform != "win32",
         description="Symlink 'python3' executable to 'python' (not PEP 394 compliant)",
     )
 
     # Optional Python modules
-    variant("readline", default=not is_windows, description="Build readline module")
+    variant("readline", default=sys.platform != "win32", description="Build readline module")
     variant("ssl", default=True, description="Build ssl module")
     variant("sqlite3", default=True, description="Build sqlite3 module")
     variant("dbm", default=True, description="Build dbm module")
@@ -147,7 +145,7 @@ class Python(Package):
     variant("crypt", default=True, description="Build crypt module", when="@:3.12 platform=darwin")
     variant("crypt", default=True, description="Build crypt module", when="@:3.12 platform=cray")
 
-    if not is_windows:
+    if sys.platform != "win32":
         depends_on("pkgconfig@0.9.0:", type="build")
         depends_on("gettext +libxml2", when="+libxml2")
         depends_on("gettext ~libxml2", when="~libxml2")
@@ -298,7 +296,7 @@ class Python(Package):
                 variants += "~tix"
 
         # Some modules are platform-dependent
-        if not is_windows:
+        if sys.platform != "win32":
             try:
                 python("-c", "import crypt", error=os.devnull)
                 variants += "+crypt"
@@ -542,7 +540,7 @@ class Python(Package):
         and an appropriately set prefix.
         """
         with working_dir(self.stage.source_path, create=True):
-            if is_windows:
+            if sys.platform == "win32":
                 pass
             else:
                 options = getattr(self, "configure_flag_args", [])
@@ -557,7 +555,7 @@ class Python(Package):
         # Windows builds use a batch script to drive
         # configure and build in one step
         with working_dir(self.stage.source_path):
-            if is_windows:
+            if sys.platform == "win32":
                 pcbuild_root = os.path.join(self.stage.source_path, "PCbuild")
                 builder_cmd = os.path.join(pcbuild_root, "build.bat")
                 try:
@@ -580,7 +578,7 @@ class Python(Package):
         :py:attr:``~.AutotoolsPackage.install_targets``
         """
         with working_dir(self.stage.source_path):
-            if is_windows:
+            if sys.platform == "win32":
                 self.win_installer(prefix)
             else:
                 make(*self.install_targets)
@@ -593,7 +591,7 @@ class Python(Package):
         If this isn't done, they'll have CC and CXX set to Spack's generic
         cc and c++. We want them to be bound to whatever compiler
         they were built with."""
-        if is_windows:
+        if sys.platform == "win32":
             return
         kwargs = {"ignore_absent": True, "backup": False, "string": True}
 
@@ -605,7 +603,7 @@ class Python(Package):
 
     @run_after("install")
     def symlink(self):
-        if is_windows:
+        if sys.platform == "win32":
             return
         spec = self.spec
         prefix = self.prefix
@@ -723,7 +721,7 @@ class Python(Package):
         # in that order if using python@3.11.0, for example.
         version = self.spec.version
         for ver in [version.up_to(2), version.up_to(1), ""]:
-            if not is_windows:
+            if sys.platform != "win32":
                 path = os.path.join(self.prefix.bin, "python{0}".format(ver))
             else:
                 path = os.path.join(self.prefix, "python{0}.exe".format(ver))
@@ -772,11 +770,11 @@ print(json.dumps(config))
 """
 
         dag_hash = self.spec.dag_hash()
-        lib_prefix = "lib" if not is_windows else ""
+        lib_prefix = "lib" if sys.platform != "win32" else ""
         if dag_hash not in self._config_vars:
             # Default config vars
             version = self.version.up_to(2)
-            if is_windows:
+            if sys.platform == "win32":
                 version = str(version).split(".")[0]
             config = {
                 # get_config_vars
@@ -886,9 +884,9 @@ print(json.dumps(config))
     @property
     def libs(self):
         py_version = self.version.up_to(2)
-        if is_windows:
+        if sys.platform == "win32":
             py_version = str(py_version).replace(".", "")
-        lib_prefix = "lib" if not is_windows else ""
+        lib_prefix = "lib" if sys.platform != "win32" else ""
         # The values of LDLIBRARY and LIBRARY aren't reliable. Intel Python uses a
         # static binary but installs shared libraries, so sysconfig reports
         # libpythonX.Y.a but only libpythonX.Y.so exists. So we add our own paths, too.
@@ -1121,7 +1119,7 @@ print(json.dumps(config))
             # fact that LDSHARED is set in the environment, therefore we export
             # the variable only if the new value is different from what we got
             # from the sysconfigdata file:
-            if config_link != new_link and not is_windows:
+            if config_link != new_link and sys.platform != "win32":
                 env.set(link_var, new_link)
 
     def setup_dependent_run_environment(self, env, dependent_spec):
@@ -1180,7 +1178,7 @@ print(json.dumps(config))
                 view.link(new_link_target, dst, spec=self.spec)
 
     def remove_files_from_view(self, view, merge_map):
-        bin_dir = self.spec.prefix.bin if not is_windows else self.spec.prefix
+        bin_dir = self.spec.prefix.bin if sys.platform != "win32" else self.spec.prefix
         for src, dst in merge_map.items():
             if not path_contains_subdirectory(src, bin_dir):
                 view.remove_file(src, dst)
diff --git a/var/spack/repos/builtin/packages/re2c/package.py b/var/spack/repos/builtin/packages/re2c/package.py
index 9311140f16..a135b2f381 100644
--- a/var/spack/repos/builtin/packages/re2c/package.py
+++ b/var/spack/repos/builtin/packages/re2c/package.py
@@ -7,8 +7,6 @@ import sys
 
 from spack.package import *
 
-is_windows = sys.platform == "win32"
-
 
 class Re2c(Package):
     """re2c: a free and open-source lexer generator for C and C++"""
@@ -33,7 +31,7 @@ class Re2c(Package):
 
     @property
     def make_tool(self):
-        if is_windows:
+        if sys.platform == "win32":
             return ninja
         else:
             return make
diff --git a/var/spack/repos/builtin/packages/scons/package.py b/var/spack/repos/builtin/packages/scons/package.py
index bb5bfea725..095fa5e275 100644
--- a/var/spack/repos/builtin/packages/scons/package.py
+++ b/var/spack/repos/builtin/packages/scons/package.py
@@ -6,8 +6,6 @@ import sys
 
 from spack.package import *
 
-is_windows = sys.platform == "win32"
-
 
 class Scons(PythonPackage):
     """SCons is a software construction tool"""
@@ -55,7 +53,7 @@ class Scons(PythonPackage):
         env.prepend_path("PYTHONPATH", self.prefix.lib.scons)
 
     def setup_dependent_package(self, module, dspec):
-        if is_windows:
+        if sys.platform == "win32":
             module.scons = Executable(self.spec.prefix.Scripts.scons)
         else:
             module.scons = Executable(self.spec.prefix.bin.scons)
diff --git a/var/spack/repos/builtin/packages/wrf/package.py b/var/spack/repos/builtin/packages/wrf/package.py
index 1318a4367d..c186d7785e 100644
--- a/var/spack/repos/builtin/packages/wrf/package.py
+++ b/var/spack/repos/builtin/packages/wrf/package.py
@@ -5,18 +5,16 @@
 
 import glob
 import re
+import sys
 import time
 from os.path import basename
 from subprocess import PIPE, Popen
-from sys import platform, stdout
 
 from llnl.util import tty
 
 from spack.package import *
 
-is_windows = platform == "win32"
-
-if not is_windows:
+if sys.platform != "win32":
     from fcntl import F_GETFL, F_SETFL, fcntl
     from os import O_NONBLOCK
 
@@ -333,7 +331,7 @@ class Wrf(Package):
             )
 
         p = Popen("./configure", stdin=PIPE, stdout=PIPE, stderr=PIPE)
-        if not is_windows:
+        if sys.platform != "win32":
             setNonBlocking(p.stdout)
             setNonBlocking(p.stderr)
 
@@ -358,7 +356,7 @@ class Wrf(Package):
                 time.sleep(0.1)  # Try to do a bit of rate limiting
                 stallcounter += 1
                 continue
-            stdout.write(line)
+            sys.stdout.write(line)
             stallcounter = 0
             outputbuf += line
             if "Enter selection" in outputbuf or "Compile for nesting" in outputbuf: