Improve byte-compilation in packaging to be independent of -O or -B.

The code I fixed to comply with PEP 3147 still had one bug: When run
under python -O, some paths for pyc files would be pyo, because I called
imp.cache_from_source without explicit debug_override argument in some
places, and under -O that would return .pyo (this is well explained in
the imp docs).  Now all code (util.byte_compile, build_py, install_lib)
can create .pyo files according to options given by users,
without interference from the calling Python’s own optimize mode.

On a related topic, I also removed the code that prevented byte
compilation under python -B.  The rationale is that packaging gives
control over the creation of pyc files to the user with its own explicit
option, and the behavior should not be changed if the calling Python
happens to run with -B for whatever reason.  I will argue that this is a
bug fix and ask to be allowed to backport this change to distutils.

Finally, I moved one nugget of information about the --compile and
--optimize options from the source into the doc.  It clears up a
misunderstanding that I (and maybe other people) had.

9 files changed, 117 insertions, 155 deletions

diff --git a/Lib/packaging/command/build_py.py b/Lib/packaging/command/build_py.py
index 0248213..5faae39 100644
--- a/Lib/packaging/command/build_py.py
+++ b/Lib/packaging/command/build_py.py
@@ -2,7 +2,6 @@
 
 import os
 import imp
-import sys
 from glob import glob
 
 from packaging import logger
@@ -14,10 +13,14 @@ from packaging.compat import Mixin2to3
 # marking public APIs
 __all__ = ['build_py']
 
+
 class build_py(Command, Mixin2to3):
 
     description = "build pure Python modules (copy to build directory)"
 
+    # The options for controlling byte compilations are two independent sets;
+    # more info in install_lib or the reST docs
+
     user_options = [
         ('build-lib=', 'd', "directory to build (copy) to"),
         ('compile', 'c', "compile .py to .pyc"),
@@ -35,7 +38,8 @@ class build_py(Command, Mixin2to3):
         ]
 
     boolean_options = ['compile', 'force']
-    negative_opt = {'no-compile' : 'compile'}
+
+    negative_opt = {'no-compile': 'compile'}
 
     def initialize_options(self):
         self.build_lib = None
@@ -116,7 +120,7 @@ class build_py(Command, Mixin2to3):
     def get_data_files(self):
         """Generate list of '(package,src_dir,build_dir,filenames)' tuples.
 
-        Helper function for `finalize_options()`.
+        Helper function for finalize_options.
         """
         data = []
         if not self.packages:
@@ -131,7 +135,7 @@ class build_py(Command, Mixin2to3):
             # Length of path to strip from found files
             plen = 0
             if src_dir:
-                plen = len(src_dir)+1
+                plen = len(src_dir) + 1
 
             # Strip directory from globbed filenames
             filenames = [
@@ -143,7 +147,7 @@ class build_py(Command, Mixin2to3):
     def find_data_files(self, package, src_dir):
         """Return filenames for package's data files in 'src_dir'.
 
-        Helper function for `get_data_files()`.
+        Helper function for get_data_files.
         """
         globs = (self.package_data.get('', [])
                  + self.package_data.get(package, []))
@@ -158,7 +162,7 @@ class build_py(Command, Mixin2to3):
     def build_package_data(self):
         """Copy data files into build directory.
 
-        Helper function for `run()`.
+        Helper function for run.
         """
         # FIXME add tests for this method
         for package, src_dir, build_dir, filenames in self.data_files:
@@ -168,16 +172,17 @@ class build_py(Command, Mixin2to3):
                 self.mkpath(os.path.dirname(target))
                 outf, copied = self.copy_file(srcfile,
                                target, preserve_mode=False)
-                if copied and srcfile in self.distribution.convert_2to3.doctests:
+                doctests = self.distribution.convert_2to3_doctests
+                if copied and srcfile in doctests:
                     self._doctests_2to3.append(outf)
 
     # XXX - this should be moved to the Distribution class as it is not
     # only needed for build_py. It also has no dependencies on this class.
     def get_package_dir(self, package):
         """Return the directory, relative to the top of the source
-           distribution, where package 'package' should be found
-           (at least according to the 'package_dir' option, if any)."""
-
+        distribution, where package 'package' should be found
+        (at least according to the 'package_dir' option, if any).
+        """
         path = package.split('.')
         if self.package_dir is not None:
             path.insert(0, self.package_dir)
@@ -188,8 +193,7 @@ class build_py(Command, Mixin2to3):
         return ''
 
     def check_package(self, package, package_dir):
-        """Helper function for `find_package_modules()` and `find_modules()'.
-        """
+        """Helper function for find_package_modules and find_modules."""
         # Empty dir name means current directory, which we can probably
         # assume exists.  Also, os.path.exists and isdir don't know about
         # my "empty string means current dir" convention, so we have to
@@ -209,8 +213,8 @@ class build_py(Command, Mixin2to3):
             if os.path.isfile(init_py):
                 return init_py
             else:
-                logger.warning(("package init file '%s' not found " +
-                                "(or not a regular file)"), init_py)
+                logger.warning("package init file %r not found "
+                               "(or not a regular file)", init_py)
 
         # Either not in a package at all (__init__.py not expected), or
         # __init__.py doesn't exist -- so don't return the filename.
@@ -218,7 +222,7 @@ class build_py(Command, Mixin2to3):
 
     def check_module(self, module, module_file):
         if not os.path.isfile(module_file):
-            logger.warning("file %s (for module %s) not found",
+            logger.warning("file %r (for module %r) not found",
                            module_file, module)
             return False
         else:
@@ -239,7 +243,7 @@ class build_py(Command, Mixin2to3):
                 module = os.path.splitext(os.path.basename(f))[0]
                 modules.append((package, module, f))
             else:
-                logger.debug("excluding %s", setup_script)
+                logger.debug("excluding %r", setup_script)
         return modules
 
     def find_modules(self):
@@ -331,7 +335,8 @@ class build_py(Command, Mixin2to3):
             outputs.append(filename)
             if include_bytecode:
                 if self.compile:
-                    outputs.append(imp.cache_from_source(filename))
+                    outputs.append(imp.cache_from_source(filename,
+                                                         debug_override=True))
                 if self.optimize > 0:
                     outputs.append(imp.cache_from_source(filename,
                                                          debug_override=False))
@@ -361,7 +366,6 @@ class build_py(Command, Mixin2to3):
     def build_modules(self):
         modules = self.find_modules()
         for package, module, module_file in modules:
-
             # Now "build" the module -- ie. copy the source file to
             # self.build_lib (the build directory for Python source).
             # (Actually, it gets copied to the directory for this package
@@ -370,7 +374,6 @@ class build_py(Command, Mixin2to3):
 
     def build_packages(self):
         for package in self.packages:
-
             # Get list of (package, module, module_file) tuples based on
             # scanning the package directory.  'package' is only included
             # in the tuple so that 'find_modules()' and
@@ -390,11 +393,6 @@ class build_py(Command, Mixin2to3):
                 self.build_module(module, module_file, package)
 
     def byte_compile(self, files):
-        if sys.dont_write_bytecode:
-            logger.warning('%s: byte-compiling is disabled, skipping.',
-                           self.get_command_name())
-            return
-
         from packaging.util import byte_compile  # FIXME use compileall
         prefix = self.build_lib
         if prefix[-1] != os.sep:
@@ -403,7 +401,6 @@ class build_py(Command, Mixin2to3):
         # XXX this code is essentially the same as the 'byte_compile()
         # method of the "install_lib" command, except for the determination
         # of the 'prefix' string.  Hmmm.
-
         if self.compile:
             byte_compile(files, optimize=0,
                          force=self.force, prefix=prefix, dry_run=self.dry_run)
diff --git a/Lib/packaging/command/install_lib.py b/Lib/packaging/command/install_lib.py
index 558966d..f6c785f 100644
--- a/Lib/packaging/command/install_lib.py
+++ b/Lib/packaging/command/install_lib.py
@@ -2,7 +2,6 @@
 
 import os
 import imp
-import sys
 import logging
 
 from packaging import logger
@@ -11,25 +10,18 @@ from packaging.errors import PackagingOptionError
 
 
 # Extension for Python source files.
+# XXX dead code?  most of the codebase checks for literal '.py'
 if hasattr(os, 'extsep'):
     PYTHON_SOURCE_EXTENSION = os.extsep + "py"
 else:
     PYTHON_SOURCE_EXTENSION = ".py"
 
+
 class install_lib(Command):
 
     description = "install all modules (extensions and pure Python)"
 
-    # The byte-compilation options are a tad confusing.  Here are the
-    # possible scenarios:
-    #   1) no compilation at all (--no-compile --no-optimize)
-    #   2) compile .pyc only (--compile --no-optimize; default)
-    #   3) compile .pyc and "level 1" .pyo (--compile --optimize)
-    #   4) compile "level 1" .pyo only (--no-compile --optimize)
-    #   5) compile .pyc and "level 2" .pyo (--compile --optimize-more)
-    #   6) compile "level 2" .pyo only (--no-compile --optimize-more)
-    #
-    # The UI for this is two option, 'compile' and 'optimize'.
+    # The options for controlling byte compilations are two independent sets:
     # 'compile' is strictly boolean, and only decides whether to
     # generate .pyc files.  'optimize' is three-way (0, 1, or 2), and
     # decides both whether to generate .pyo files and what level of
@@ -37,7 +29,7 @@ class install_lib(Command):
 
     user_options = [
         ('install-dir=', 'd', "directory to install to"),
-        ('build-dir=','b', "build directory (where to install from)"),
+        ('build-dir=', 'b', "build directory (where to install from)"),
         ('force', 'f', "force installation (overwrite existing files)"),
         ('compile', 'c', "compile .py to .pyc [default]"),
         ('no-compile', None, "don't compile .py files"),
@@ -48,7 +40,8 @@ class install_lib(Command):
         ]
 
     boolean_options = ['force', 'compile', 'skip-build']
-    negative_opt = {'no-compile' : 'compile'}
+
+    negative_opt = {'no-compile': 'compile'}
 
     def initialize_options(self):
         # let the 'install_dist' command dictate our installation directory
@@ -66,7 +59,8 @@ class install_lib(Command):
         self.set_undefined_options('install_dist',
                                    ('build_lib', 'build_dir'),
                                    ('install_lib', 'install_dir'),
-                                   'force', 'compile', 'optimize', 'skip_build')
+                                   'force', 'compile', 'optimize',
+                                   'skip_build')
 
         if self.compile is None:
             self.compile = True
@@ -115,14 +109,6 @@ class install_lib(Command):
         return outfiles
 
     def byte_compile(self, files):
-        if sys.dont_write_bytecode:
-            # XXX do we want this?  because a Python runs without bytecode
-            # doesn't mean that the *dists should not contain bytecode
-            #--or does it?
-            logger.warning('%s: byte-compiling is disabled, skipping.',
-                           self.get_command_name())
-            return
-
         from packaging.util import byte_compile  # FIXME use compileall
 
         # Get the "--root" directory supplied to the "install_dist" command,
@@ -138,13 +124,11 @@ class install_lib(Command):
         if self.compile:
             byte_compile(files, optimize=0,
                          force=self.force, prefix=install_root,
-                         dry_run=self.dry_run)
+                         verbose=verbose, dry_run=self.dry_run)
         if self.optimize > 0:
             byte_compile(files, optimize=self.optimize,
                          force=self.force, prefix=install_root,
-                         verbose=verbose,
-                         dry_run=self.dry_run)
-
+                         verbose=verbose, dry_run=self.dry_run)
 
     # -- Utility methods -----------------------------------------------
 
@@ -173,14 +157,14 @@ class install_lib(Command):
             if ext != PYTHON_SOURCE_EXTENSION:
                 continue
             if self.compile:
-                bytecode_files.append(imp.cache_from_source(py_file))
+                bytecode_files.append(imp.cache_from_source(
+                    py_file, debug_override=True))
             if self.optimize > 0:
                 bytecode_files.append(imp.cache_from_source(
                     py_file, debug_override=False))
 
         return bytecode_files
 
-
     # -- External interface --------------------------------------------
     # (called by outsiders)
 
diff --git a/Lib/packaging/errors.py b/Lib/packaging/errors.py
index 8924a2d..8878129 100644
--- a/Lib/packaging/errors.py
+++ b/Lib/packaging/errors.py
@@ -72,10 +72,6 @@ class PackagingTemplateError(PackagingError):
     """Syntax error in a file list template."""
 
 
-class PackagingByteCompileError(PackagingError):
-    """Byte compile error."""
-
-
 class PackagingPyPIError(PackagingError):
     """Any problem occuring during using the indexes."""
 
diff --git a/Lib/packaging/tests/support.py b/Lib/packaging/tests/support.py
index 6e26ea4..66890c9 100644
--- a/Lib/packaging/tests/support.py
+++ b/Lib/packaging/tests/support.py
@@ -53,7 +53,7 @@ __all__ = [
     # misc. functions and decorators
     'fake_dec', 'create_distribution', 'copy_xxmodule_c', 'fixup_build_ext',
     # imported from this module for backport purposes
-    'unittest', 'requires_zlib', 'skip_unless_symlink',
+    'unittest', 'requires_zlib', 'skip_2to3_optimize', 'skip_unless_symlink',
 ]
 
 
@@ -357,3 +357,7 @@ try:
 except ImportError:
     skip_unless_symlink = unittest.skip(
         'requires test.support.skip_unless_symlink')
+
+
+skip_2to3_optimize = unittest.skipIf(sys.flags.optimize,
+                                     "2to3 doesn't work under -O")
diff --git a/Lib/packaging/tests/test_command_build_py.py b/Lib/packaging/tests/test_command_build_py.py
index 9d519e3..4d93faa 100644
--- a/Lib/packaging/tests/test_command_build_py.py
+++ b/Lib/packaging/tests/test_command_build_py.py
@@ -62,12 +62,8 @@ class BuildPyTestCase(support.TempdirManager,
         pycache_dir = os.path.join(pkgdest, "__pycache__")
         self.assertIn("__init__.py", files)
         self.assertIn("README.txt", files)
-        if sys.dont_write_bytecode:
-            self.assertFalse(os.path.exists(pycache_dir))
-        else:
-            # XXX even with -O, packaging writes pyc, not pyo; bug?
-            pyc_files = os.listdir(pycache_dir)
-            self.assertIn("__init__.%s.pyc" % imp.get_tag(), pyc_files)
+        pyc_files = os.listdir(pycache_dir)
+        self.assertIn("__init__.%s.pyc" % imp.get_tag(), pyc_files)
 
     def test_empty_package_dir(self):
         # See SF 1668596/1720897.
@@ -102,7 +98,6 @@ class BuildPyTestCase(support.TempdirManager,
             os.chdir(cwd)
             sys.stdout = old_stdout
 
-    @unittest.skipIf(sys.dont_write_bytecode, 'byte-compile disabled')
     def test_byte_compile(self):
         project_dir, dist = self.create_dist(py_modules=['boiledeggs'])
         os.chdir(project_dir)
@@ -118,7 +113,6 @@ class BuildPyTestCase(support.TempdirManager,
         found = os.listdir(os.path.join(cmd.build_lib, '__pycache__'))
         self.assertEqual(found, ['boiledeggs.%s.pyc' % imp.get_tag()])
 
-    @unittest.skipIf(sys.dont_write_bytecode, 'byte-compile disabled')
     def test_byte_compile_optimized(self):
         project_dir, dist = self.create_dist(py_modules=['boiledeggs'])
         os.chdir(project_dir)
@@ -136,21 +130,13 @@ class BuildPyTestCase(support.TempdirManager,
         self.assertEqual(sorted(found), ['boiledeggs.%s.pyc' % imp.get_tag(),
                                          'boiledeggs.%s.pyo' % imp.get_tag()])
 
-    def test_dont_write_bytecode(self):
-        # makes sure byte_compile is not used
-        pkg_dir, dist = self.create_dist()
-        cmd = build_py(dist)
-        cmd.compile = True
-        cmd.optimize = 1
-
-        old_dont_write_bytecode = sys.dont_write_bytecode
+    def test_byte_compile_under_B(self):
+        # make sure byte compilation works under -B (dont_write_bytecode)
+        self.addCleanup(setattr, sys, 'dont_write_bytecode',
+                        sys.dont_write_bytecode)
         sys.dont_write_bytecode = True
-        try:
-            cmd.byte_compile([])
-        finally:
-            sys.dont_write_bytecode = old_dont_write_bytecode
-
-        self.assertIn('byte-compiling is disabled', self.get_logs()[0])
+        self.test_byte_compile()
+        self.test_byte_compile_optimized()
 
 
 def test_suite():
diff --git a/Lib/packaging/tests/test_command_install_lib.py b/Lib/packaging/tests/test_command_install_lib.py
index 3f36822..e58e812 100644
--- a/Lib/packaging/tests/test_command_install_lib.py
+++ b/Lib/packaging/tests/test_command_install_lib.py
@@ -17,7 +17,7 @@ class InstallLibTestCase(support.TempdirManager,
     restore_environ = ['PYTHONPATH']
 
     def test_finalize_options(self):
-        pkg_dir, dist = self.create_dist()
+        dist = self.create_dist()[1]
         cmd = install_lib(dist)
 
         cmd.finalize_options()
@@ -34,71 +34,73 @@ class InstallLibTestCase(support.TempdirManager,
         cmd.finalize_options()
         self.assertEqual(cmd.optimize, 2)
 
-    @unittest.skipIf(sys.dont_write_bytecode, 'byte-compile disabled')
     def test_byte_compile(self):
-        pkg_dir, dist = self.create_dist()
-        os.chdir(pkg_dir)
+        project_dir, dist = self.create_dist()
+        os.chdir(project_dir)
         cmd = install_lib(dist)
         cmd.compile = True
         cmd.optimize = 1
 
-        f = os.path.join(pkg_dir, 'foo.py')
+        f = os.path.join(project_dir, 'foo.py')
         self.write_file(f, '# python file')
         cmd.byte_compile([f])
-        pyc_file = imp.cache_from_source('foo.py')
+        pyc_file = imp.cache_from_source('foo.py', debug_override=True)
         pyo_file = imp.cache_from_source('foo.py', debug_override=False)
         self.assertTrue(os.path.exists(pyc_file))
         self.assertTrue(os.path.exists(pyo_file))
 
+    def test_byte_compile_under_B(self):
+        # make sure byte compilation works under -B (dont_write_bytecode)
+        self.addCleanup(setattr, sys, 'dont_write_bytecode',
+                        sys.dont_write_bytecode)
+        sys.dont_write_bytecode = True
+        self.test_byte_compile()
+
     def test_get_outputs(self):
-        pkg_dir, dist = self.create_dist()
+        project_dir, dist = self.create_dist()
+        os.chdir(project_dir)
+        os.mkdir('spam')
         cmd = install_lib(dist)
 
         # setting up a dist environment
         cmd.compile = True
         cmd.optimize = 1
-        cmd.install_dir = pkg_dir
-        f = os.path.join(pkg_dir, '__init__.py')
+        cmd.install_dir = self.mkdtemp()
+        f = os.path.join(project_dir, 'spam', '__init__.py')
         self.write_file(f, '# python package')
         cmd.distribution.ext_modules = [Extension('foo', ['xxx'])]
-        cmd.distribution.packages = [pkg_dir]
+        cmd.distribution.packages = ['spam']
 
-        # make sure the build_lib is set the temp dir
-        build_dir = os.path.split(pkg_dir)[0]
+        # make sure the build_lib is set the temp dir  # XXX what?  this is not
+        # needed in the same distutils test and should work without manual
+        # intervention
+        build_dir = os.path.split(project_dir)[0]
         cmd.get_finalized_command('build_py').build_lib = build_dir
 
-        # get_output should return 4 elements
-        self.assertEqual(len(cmd.get_outputs()), 4)
+        # get_outputs should return 4 elements: spam/__init__.py, .pyc and
+        # .pyo, foo.import-tag-abiflags.so / foo.pyd
+        outputs = cmd.get_outputs()
+        self.assertEqual(len(outputs), 4, outputs)
 
     def test_get_inputs(self):
-        pkg_dir, dist = self.create_dist()
+        project_dir, dist = self.create_dist()
+        os.chdir(project_dir)
+        os.mkdir('spam')
         cmd = install_lib(dist)
 
         # setting up a dist environment
         cmd.compile = True
         cmd.optimize = 1
-        cmd.install_dir = pkg_dir
-        f = os.path.join(pkg_dir, '__init__.py')
+        cmd.install_dir = self.mkdtemp()
+        f = os.path.join(project_dir, 'spam', '__init__.py')
         self.write_file(f, '# python package')
         cmd.distribution.ext_modules = [Extension('foo', ['xxx'])]
-        cmd.distribution.packages = [pkg_dir]
-
-        # get_input should return 2 elements
-        self.assertEqual(len(cmd.get_inputs()), 2)
-
-    def test_dont_write_bytecode(self):
-        # makes sure byte_compile is not used
-        pkg_dir, dist = self.create_dist()
-        cmd = install_lib(dist)
-        cmd.compile = True
-        cmd.optimize = 1
-
-        self.addCleanup(setattr, sys, 'dont_write_bytecode',
-                        sys.dont_write_bytecode)
-        sys.dont_write_bytecode = True
-        cmd.byte_compile([])
+        cmd.distribution.packages = ['spam']
 
-        self.assertIn('byte-compiling is disabled', self.get_logs()[0])
+        # get_inputs should return 2 elements: spam/__init__.py and
+        # foo.import-tag-abiflags.so / foo.pyd
+        inputs = cmd.get_inputs()
+        self.assertEqual(len(inputs), 2, inputs)
 
 
 def test_suite():
diff --git a/Lib/packaging/tests/test_mixin2to3.py b/Lib/packaging/tests/test_mixin2to3.py
index 000a992..c439bcb 100644
--- a/Lib/packaging/tests/test_mixin2to3.py
+++ b/Lib/packaging/tests/test_mixin2to3.py
@@ -8,6 +8,7 @@ class Mixin2to3TestCase(support.TempdirManager,
                         support.LoggingCatcher,
                         unittest.TestCase):
 
+    @support.skip_2to3_optimize
     def test_convert_code_only(self):
         # used to check if code gets converted properly.
         code = "print 'test'"
diff --git a/Lib/packaging/tests/test_util.py b/Lib/packaging/tests/test_util.py
index 1cf5c93..00d61e0 100644
--- a/Lib/packaging/tests/test_util.py
+++ b/Lib/packaging/tests/test_util.py
@@ -10,7 +10,7 @@ import subprocess
 from io import StringIO
 
 from packaging.errors import (
-    PackagingPlatformError, PackagingByteCompileError, PackagingFileError,
+    PackagingPlatformError, PackagingFileError,
     PackagingExecError, InstallationException)
 from packaging import util
 from packaging.dist import Distribution
@@ -138,15 +138,8 @@ class UtilTestCase(support.EnvironRestorer,
             self._uname = None
         os.uname = self._get_uname
 
-        # patching POpen
-        self.old_find_executable = util.find_executable
-        util.find_executable = self._find_executable
-        self._exes = {}
-        self.old_popen = subprocess.Popen
-        self.old_stdout = sys.stdout
-        self.old_stderr = sys.stderr
-        FakePopen.test_class = self
-        subprocess.Popen = FakePopen
+    def _get_uname(self):
+        return self._uname
 
     def tearDown(self):
         # getting back the environment
@@ -161,17 +154,24 @@ class UtilTestCase(support.EnvironRestorer,
             os.uname = self.uname
         else:
             del os.uname
+        super(UtilTestCase, self).tearDown()
+
+    def mock_popen(self):
+        self.old_find_executable = util.find_executable
+        util.find_executable = self._find_executable
+        self._exes = {}
+        self.old_popen = subprocess.Popen
+        self.old_stdout = sys.stdout
+        self.old_stderr = sys.stderr
+        FakePopen.test_class = self
+        subprocess.Popen = FakePopen
+        self.addCleanup(self.unmock_popen)
+
+    def unmock_popen(self):
         util.find_executable = self.old_find_executable
         subprocess.Popen = self.old_popen
         sys.old_stdout = self.old_stdout
         sys.old_stderr = self.old_stderr
-        super(UtilTestCase, self).tearDown()
-
-    def _set_uname(self, uname):
-        self._uname = uname
-
-    def _get_uname(self):
-        return self._uname
 
     def test_convert_path(self):
         # linux/mac
@@ -283,6 +283,7 @@ class UtilTestCase(support.EnvironRestorer,
         return None
 
     def test_get_compiler_versions(self):
+        self.mock_popen()
         # get_versions calls distutils.spawn.find_executable on
         # 'gcc', 'ld' and 'dllwrap'
         self.assertEqual(get_compiler_versions(), (None, None, None))
@@ -323,15 +324,12 @@ class UtilTestCase(support.EnvironRestorer,
         res = get_compiler_versions()
         self.assertEqual(res[2], None)
 
-    def test_dont_write_bytecode(self):
-        # makes sure byte_compile raise a PackagingError
-        # if sys.dont_write_bytecode is True
-        old_dont_write_bytecode = sys.dont_write_bytecode
+    def test_byte_compile_under_B(self):
+        # make sure byte compilation works under -B (dont_write_bytecode)
+        self.addCleanup(setattr, sys, 'dont_write_bytecode',
+                        sys.dont_write_bytecode)
         sys.dont_write_bytecode = True
-        try:
-            self.assertRaises(PackagingByteCompileError, byte_compile, [])
-        finally:
-            sys.dont_write_bytecode = old_dont_write_bytecode
+        byte_compile([])
 
     def test_newer(self):
         self.assertRaises(PackagingFileError, util.newer, 'xxx', 'xxx')
@@ -418,6 +416,7 @@ class UtilTestCase(support.EnvironRestorer,
         self.assertRaises(ImportError, resolve_name, 'a.b.Spam')
         self.assertRaises(ImportError, resolve_name, 'a.b.c.Spam')
 
+    @support.skip_2to3_optimize
     def test_run_2to3_on_code(self):
         content = "print 'test'"
         converted_content = "print('test')"
@@ -431,6 +430,7 @@ class UtilTestCase(support.EnvironRestorer,
         file_handle.close()
         self.assertEqual(new_content, converted_content)
 
+    @support.skip_2to3_optimize
     def test_run_2to3_on_doctests(self):
         # to check if text files containing doctests only get converted.
         content = ">>> print 'test'\ntest\n"
@@ -448,8 +448,6 @@ class UtilTestCase(support.EnvironRestorer,
     @unittest.skipUnless(os.name in ('nt', 'posix'),
                          'runs only under posix or nt')
     def test_spawn(self):
-        # no patching of Popen here
-        subprocess.Popen = self.old_popen
         tmpdir = self.mkdtemp()
 
         # creating something executable
@@ -545,8 +543,6 @@ class UtilTestCase(support.EnvironRestorer,
         self.assertEqual(args['py_modules'], dist.py_modules)
 
     def test_generate_setup_py(self):
-        # undo subprocess.Popen monkey-patching before using assert_python_*
-        subprocess.Popen = self.old_popen
         os.chdir(self.mkdtemp())
         self.write_file('setup.cfg', textwrap.dedent("""\
             [metadata]
diff --git a/Lib/packaging/util.py b/Lib/packaging/util.py
index 8dd715f..e76e3c3 100644
--- a/Lib/packaging/util.py
+++ b/Lib/packaging/util.py
@@ -20,8 +20,8 @@ from configparser import RawConfigParser
 
 from packaging import logger
 from packaging.errors import (PackagingPlatformError, PackagingFileError,
-                              PackagingByteCompileError, PackagingExecError,
-                              InstallationException, PackagingInternalError)
+                              PackagingExecError, InstallationException,
+                              PackagingInternalError)
 
 __all__ = [
     # file dependencies
@@ -325,12 +325,10 @@ def byte_compile(py_files, optimize=0, force=False, prefix=None,
     the source for details).  The 'direct' flag is used by the script
     generated in indirect mode; unless you know what you're doing, leave
     it set to None.
-    """
-    # nothing is done if sys.dont_write_bytecode is True
-    # FIXME this should not raise an error
-    if sys.dont_write_bytecode:
-        raise PackagingByteCompileError('byte-compiling is disabled.')
 
+    This function is independent from the running Python's -O or -B options;
+    it is fully controlled by the parameters passed in.
+    """
     # First, if the caller didn't force us into direct or indirect mode,
     # figure out which mode we should be in.  We take a conservative
     # approach: choose direct mode *only* if the current interpreter is
@@ -417,12 +415,10 @@ byte_compile(files, optimize=%r, force=%r,
             # Terminology from the py_compile module:
             #   cfile - byte-compiled file
             #   dfile - purported source filename (same as 'file' by default)
-            if optimize >= 0:
-                cfile = imp.cache_from_source(file,
-                                              debug_override=not optimize)
-            else:
-                cfile = imp.cache_from_source(file)
+            debug_override = not optimize
+            cfile = imp.cache_from_source(file, debug_override)
             dfile = file
+
             if prefix:
                 if file[:len(prefix)] != prefix:
                     raise ValueError("invalid prefix: filename %r doesn't "