Make zlib required instead of optional.

This simplifies code by removing a pile of conditionals and
alternative logic.

Further simplification could be done in `Modules/binascii.c` to
simply have binascii.crc32 be a reference to zlib.crc32.

Also the conditional logic around zlib inflaceCopy existing and
`HAVE_ZLIB_COPY` can likely be removed as that API was added to zlib
in 2003.

The Windows build already treats zlib as required.

Author: gpshead

Lib/distutils/tests/test_archive_util.py

@@ -30,11 +30,7 @@
 except ImportError:
     ZIP_SUPPORT = find_executable('zip')
 
-try:
-    import zlib
-    ZLIB_SUPPORT = True
-except ImportError:
-    ZLIB_SUPPORT = False
+import zlib
 
 try:
     import bz2
@@ -63,15 +59,13 @@ class ArchiveUtilTestCase(support.TempdirManager,
                           support.LoggingSilencer,
                           unittest.TestCase):
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_make_tarball(self, name='archive'):
         # creating something to tar
         tmpdir = self._create_files()
         self._make_tarball(tmpdir, name, '.tar.gz')
         # trying an uncompressed one
         self._make_tarball(tmpdir, name, '.tar', compress=None)
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_make_tarball_gzip(self):
         tmpdir = self._create_files()
         self._make_tarball(tmpdir, 'archive', '.tar.gz', compress='gzip')
@@ -144,9 +138,8 @@ def _create_files(self):
         os.mkdir(os.path.join(dist, 'sub2'))
         return tmpdir
 
-    @unittest.skipUnless(find_executable('tar') and find_executable('gzip')
-                         and ZLIB_SUPPORT,
-                         'Need the tar, gzip and zlib command to run')
+    @unittest.skipUnless(find_executable('tar') and find_executable('gzip'),
+                         'Need the tar and gzip commands to run')
     def test_tarfile_vs_tar(self):
         tmpdir =  self._create_files()
         tmpdir2 = self.mkdtemp()
@@ -234,8 +227,7 @@ def test_compress_deprecated(self):
         self.assertFalse(os.path.exists(tarball))
         self.assertEqual(len(w.warnings), 1)
 
-    @unittest.skipUnless(ZIP_SUPPORT and ZLIB_SUPPORT,
-                         'Need zip and zlib support to run')
+    @unittest.skipUnless(ZIP_SUPPORT, 'Need zip support to run')
     def test_make_zipfile(self):
         # creating something to tar
         tmpdir = self._create_files()
@@ -249,32 +241,6 @@ def test_make_zipfile(self):
         with zipfile.ZipFile(tarball) as zf:
             self.assertEqual(sorted(zf.namelist()), self._zip_created_files)
 
-    @unittest.skipUnless(ZIP_SUPPORT, 'Need zip support to run')
-    def test_make_zipfile_no_zlib(self):
-        patch(self, archive_util.zipfile, 'zlib', None)  # force zlib ImportError
-
-        called = []
-        zipfile_class = zipfile.ZipFile
-        def fake_zipfile(*a, **kw):
-            if kw.get('compression', None) == zipfile.ZIP_STORED:
-                called.append((a, kw))
-            return zipfile_class(*a, **kw)
-
-        patch(self, archive_util.zipfile, 'ZipFile', fake_zipfile)
-
-        # create something to tar and compress
-        tmpdir = self._create_files()
-        base_name = os.path.join(self.mkdtemp(), 'archive')
-        with change_cwd(tmpdir):
-            make_zipfile(base_name, 'dist')
-
-        tarball = base_name + '.zip'
-        self.assertEqual(called,
-                         [((tarball, "w"), {'compression': zipfile.ZIP_STORED})])
-        self.assertTrue(os.path.exists(tarball))
-        with zipfile.ZipFile(tarball) as zf:
-            self.assertEqual(sorted(zf.namelist()), self._zip_created_files)
-
     def test_check_archive_formats(self):
         self.assertEqual(check_archive_formats(['gztar', 'xxx', 'zip']),
                          'xxx')
@@ -308,7 +274,6 @@ def test_make_archive_tar(self):
         self.assertEqual(os.path.basename(res), 'archive.tar')
         self.assertEqual(self._tarinfo(res), self._created_files)
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_make_archive_gztar(self):
         base_dir =  self._create_files()
         base_name = os.path.join(self.mkdtemp() , 'archive')
@@ -362,7 +327,6 @@ def test_make_archive_owner_group(self):
                            owner='kjhkjhkjg', group='oihohoh')
         self.assertTrue(os.path.exists(res))
 
-    @unittest.skipUnless(ZLIB_SUPPORT, "Requires zlib")
     @unittest.skipUnless(UID_GID_SUPPORT, "Requires grp and pwd support")
     def test_tarfile_root_owner(self):
         tmpdir =  self._create_files()

Lib/distutils/tests/test_bdist_dumb.py

@@ -2,8 +2,9 @@
 
 import os
 import sys
-import zipfile
 import unittest
+import zipfile
+import zlib
 from test.support import run_unittest
 
 from distutils.core import Distribution
@@ -19,11 +20,6 @@
 
 """
 
-try:
-    import zlib
-    ZLIB_SUPPORT = True
-except ImportError:
-    ZLIB_SUPPORT = False
 
 
 class BuildDumbTestCase(support.TempdirManager,
@@ -42,7 +38,6 @@ def tearDown(self):
         sys.argv[:] = self.old_sys_argv[1]
         super(BuildDumbTestCase, self).tearDown()
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_simple_built(self):
 
         # let's create a simple package

Lib/distutils/tests/test_bdist_rpm.py

@@ -3,7 +3,7 @@
 import unittest
 import sys
 import os
-from test.support import run_unittest, requires_zlib
+from test.support import run_unittest
 
 from distutils.core import Distribution
 from distutils.command.bdist_rpm import bdist_rpm
@@ -44,7 +44,6 @@ def tearDown(self):
     # spurious sdtout/stderr output under Mac OS X
     @unittest.skipUnless(sys.platform.startswith('linux'),
                          'spurious sdtout/stderr output under Mac OS X')
-    @requires_zlib()
     @unittest.skipIf(find_executable('rpm') is None,
                      'the rpm command is not found')
     @unittest.skipIf(find_executable('rpmbuild') is None,
@@ -87,7 +86,6 @@ def test_quiet(self):
     # spurious sdtout/stderr output under Mac OS X
     @unittest.skipUnless(sys.platform.startswith('linux'),
                          'spurious sdtout/stderr output under Mac OS X')
-    @requires_zlib()
     # http://bugs.python.org/issue1533164
     @unittest.skipIf(find_executable('rpm') is None,
                      'the rpm command is not found')

Lib/distutils/tests/test_sdist.py

@@ -4,17 +4,12 @@
 import unittest
 import warnings
 import zipfile
+import zlib
 from os.path import join
 from textwrap import dedent
 from test.support import captured_stdout, run_unittest
 from test.support.warnings_helper import check_warnings
 
-try:
-    import zlib
-    ZLIB_SUPPORT = True
-except ImportError:
-    ZLIB_SUPPORT = False
-
 try:
     import grp
     import pwd
@@ -88,7 +83,6 @@ def get_cmd(self, metadata=None):
         cmd.dist_dir = 'dist'
         return dist, cmd
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_prune_file_list(self):
         # this test creates a project with some VCS dirs and an NFS rename
         # file, then launches sdist to check they get pruned on all systems
@@ -133,7 +127,6 @@ def test_prune_file_list(self):
                     'somecode/', 'somecode/__init__.py']
         self.assertEqual(sorted(content), ['fake-1.0/' + x for x in expected])
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     @unittest.skipIf(find_executable('tar') is None,
                      "The tar command is not found")
     @unittest.skipIf(find_executable('gzip') is None,
@@ -166,7 +159,6 @@ def test_make_distribution(self):
         result.sort()
         self.assertEqual(result, ['fake-1.0.tar', 'fake-1.0.tar.gz'])
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_add_defaults(self):
 
         # http://bugs.python.org/issue2279
@@ -245,7 +237,6 @@ def test_add_defaults(self):
             f.close()
         self.assertEqual(manifest, MANIFEST % {'sep': os.sep})
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_metadata_check_option(self):
         # testing the `medata-check` option
         dist, cmd = self.get_cmd(metadata={})
@@ -332,7 +323,6 @@ def test_invalid_template_wrong_path(self):
         # this used to crash instead of raising a warning: #8286
         self._check_template('include examples/')
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_get_file_list(self):
         # make sure MANIFEST is recalculated
         dist, cmd = self.get_cmd()
@@ -374,7 +364,6 @@ def test_get_file_list(self):
         self.assertEqual(len(manifest2), 6)
         self.assertIn('doc2.txt', manifest2[-1])
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_manifest_marker(self):
         # check that autogenerated MANIFESTs have a marker
         dist, cmd = self.get_cmd()
@@ -391,7 +380,6 @@ def test_manifest_marker(self):
         self.assertEqual(manifest[0],
                          '# file GENERATED by distutils, do NOT edit')
 
-    @unittest.skipUnless(ZLIB_SUPPORT, "Need zlib support to run")
     def test_manifest_comments(self):
         # make sure comments don't cause exceptions or wrong includes
         contents = dedent("""\
@@ -408,7 +396,6 @@ def test_manifest_comments(self):
         cmd.run()
         self.assertEqual(cmd.filelist.files, ['good.py'])
 
-    @unittest.skipUnless(ZLIB_SUPPORT, 'Need zlib support to run')
     def test_manual_manifest(self):
         # check that a MANIFEST without a marker is left alone
         dist, cmd = self.get_cmd()
@@ -438,7 +425,6 @@ def test_manual_manifest(self):
         self.assertEqual(sorted(filenames), ['fake-1.0', 'fake-1.0/PKG-INFO',
                                              'fake-1.0/README.manual'])
 
-    @unittest.skipUnless(ZLIB_SUPPORT, "requires zlib")
     @unittest.skipUnless(UID_GID_SUPPORT, "Requires grp and pwd support")
     @unittest.skipIf(find_executable('tar') is None,
                      "The tar command is not found")

Lib/encodings/zlib_codec.py

@@ -6,7 +6,7 @@
 """
 
 import codecs
-import zlib # this codec needs the optional zlib module !
+import zlib
 
 ### Codec APIs
 

Lib/shutil.py

@@ -10,13 +10,7 @@
 import fnmatch
 import collections
 import errno
-
-try:
-    import zlib
-    del zlib
-    _ZLIB_SUPPORTED = True
-except ImportError:
-    _ZLIB_SUPPORTED = False
+import zlib
 
 try:
     import bz2
@@ -911,7 +905,7 @@ def _make_tarball(base_name, base_dir, compress="gzip", verbose=0, dry_run=0,
     """
     if compress is None:
         tar_compression = ''
-    elif _ZLIB_SUPPORTED and compress == 'gzip':
+    elif compress == 'gzip':
         tar_compression = 'gz'
     elif _BZ2_SUPPORTED and compress == 'bzip2':
         tar_compression = 'bz2'
@@ -1006,10 +1000,9 @@ def _make_zipfile(base_name, base_dir, verbose=0, dry_run=0, logger=None):
     'tar':   (_make_tarball, [('compress', None)], "uncompressed tar file"),
 }
 
-if _ZLIB_SUPPORTED:
-    _ARCHIVE_FORMATS['gztar'] = (_make_tarball, [('compress', 'gzip')],
-                                "gzip'ed tar-file")
-    _ARCHIVE_FORMATS['zip'] = (_make_zipfile, [], "ZIP file")
+_ARCHIVE_FORMATS['gztar'] = (_make_tarball, [('compress', 'gzip')],
+                            "gzip'ed tar-file")
+_ARCHIVE_FORMATS['zip'] = (_make_zipfile, [], "ZIP file")
 
 if _BZ2_SUPPORTED:
     _ARCHIVE_FORMATS['bztar'] = (_make_tarball, [('compress', 'bzip2')],
@@ -1217,12 +1210,9 @@ def _unpack_tarfile(filename, extract_dir):
 _UNPACK_FORMATS = {
     'tar':   (['.tar'], _unpack_tarfile, [], "uncompressed tar file"),
     'zip':   (['.zip'], _unpack_zipfile, [], "ZIP file"),
+    'gztar': (['.tar.gz', '.tgz'], _unpack_tarfile, [], "gzip'ed tar-file"),
 }
 
-if _ZLIB_SUPPORTED:
-    _UNPACK_FORMATS['gztar'] = (['.tar.gz', '.tgz'], _unpack_tarfile, [],
-                                "gzip'ed tar-file")
-
 if _BZ2_SUPPORTED:
     _UNPACK_FORMATS['bztar'] = (['.tar.bz2', '.tbz2'], _unpack_tarfile, [],
                                 "bzip2'ed tar-file")

Lib/tarfile.py

@@ -361,10 +361,7 @@ def __init__(self, name, mode, comptype, fileobj, bufsize):
 
         try:
             if comptype == "gz":
-                try:
-                    import zlib
-                except ImportError:
-                    raise CompressionError("zlib module is not available") from None
+                import zlib
                 self.zlib = zlib
                 self.crc = zlib.crc32(b"")
                 if mode == "r":
@@ -2359,13 +2356,10 @@ def next(self):
             except SubsequentHeaderError as e:
                 raise ReadError(str(e)) from None
             except Exception as e:
-                try:
-                    import zlib
-                    if isinstance(e, zlib.error):
-                        raise ReadError(f'zlib error: {e}') from None
-                    else:
-                        raise e
-                except ImportError:
+                import zlib
+                if isinstance(e, zlib.error):
+                    raise ReadError(f'zlib error: {e}') from None
+                else:
                     raise e
             break
 

Lib/test/pythoninfo.py

@@ -1,7 +1,6 @@
 """
 Collect various information about Python to help debugging test failures.
 """
-from __future__ import print_function
 import errno
 import re
 import sys
@@ -558,11 +557,7 @@ def collect_sqlite(info_add):
 
 
 def collect_zlib(info_add):
-    try:
-        import zlib
-    except ImportError:
-        return
-
+    import zlib
     attributes = ('ZLIB_VERSION', 'ZLIB_RUNTIME_VERSION')
     copy_attributes(info_add, zlib, 'zlib.%s', attributes)
 

Lib/test/test_codecs.py

@@ -2700,13 +2700,10 @@ def test_seek0(self):
     "rot_13": ["rot13"],
 }
 
-try:
-    import zlib
-except ImportError:
-    zlib = None
-else:
-    bytes_transform_encodings.append("zlib_codec")
-    transform_aliases["zlib_codec"] = ["zip", "zlib"]
+import zlib
+bytes_transform_encodings.append("zlib_codec")
+transform_aliases["zlib_codec"] = ["zip", "zlib"]
+
 try:
     import bz2
 except ImportError:
@@ -2807,7 +2804,6 @@ def test_binary_to_text_denylists_text_transforms(self):
                     bad_input.decode("rot_13")
                 self.assertIsNone(failure.exception.__cause__)
 
-    @unittest.skipUnless(zlib, "Requires zlib support")
     def test_custom_zlib_error_is_wrapped(self):
         # Check zlib codec gives a good error for malformed input
         msg = "^decoding with 'zlib_codec' codec failed"