Description: Update source code for Python 3
 Python 2 reached End-of-Life in January 2020. This patch completely
 removes Python 2 support per release team guidance.
Author: Olek Wojnar <olek@debian.org>
Forwarded: https://github.com/bazelbuild/bazel/pull/11201
Last-Update: 2020-07-23

--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPythonSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPythonSemantics.java
@@ -221,7 +221,7 @@
      * logic will extract the zip's runfiles into a temporary directory.
      *
      * The stub script has a shebang pointing to a first-stage Python interpreter (as of this
-     * writing "#!/usr/bin/env python"). When a zip file is built on unix, this shebang is also
+     * writing "#!/usr/bin/env python3"). When a zip file is built on unix, this shebang is also
      * prepended to the final zip artifact. On Windows shebangs are ignored, and the launcher
      * runs the first stage with an interpreter whose path is passed in as LaunchInfo.
      */
@@ -253,7 +253,7 @@
         PathFragment shExecutable = ShToolchain.getPathOrError(ruleContext);
         // TODO(#8685): Remove this special-case handling as part of making the proper shebang a
         // property of the Python toolchain configuration.
-        String pythonExecutableName = OS.getCurrent() == OS.OPENBSD ? "python3" : "python";
+        String pythonExecutableName = "python3";
         // NOTE: keep the following line intact to support nix builds
         String pythonShebang = "#!/usr/bin/env " + pythonExecutableName;
         ruleContext.registerAction(
--- a/src/test/py/bazel/launcher_test.py
+++ b/src/test/py/bazel/launcher_test.py
@@ -355,7 +355,7 @@
         'helloworld(', '  name = "hello",', '  out = "hello.txt",', ')'
     ])
     foo_py = self.ScratchFile('foo/foo.py', [
-        '#!/usr/bin/env python',
+        '#!/usr/bin/env python3',
         'import sys',
         'if len(sys.argv) == 2:',
         '  with open(sys.argv[1], "w") as f:',
@@ -364,7 +364,7 @@
         '  print("Hello World!")',
     ])
     test_py = self.ScratchFile('foo/test.py', [
-        '#!/usr/bin/env python',
+        '#!/usr/bin/env python3',
         'import unittest',
         'class MyTest(unittest.TestCase):',
         '  def test_dummy(self):',
--- a/tools/j2objc/j2objc_header_map.py
+++ b/tools/j2objc/j2objc_header_map.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python2.7
+#!/usr/bin/python3
 
 # Copyright 2017 The Bazel Authors. All rights reserved.
 #
--- a/tools/j2objc/j2objc_wrapper.py
+++ b/tools/j2objc/j2objc_wrapper.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python2.7
+#!/usr/bin/python3
 
 # Copyright 2015 The Bazel Authors. All rights reserved.
 #
@@ -25,7 +25,7 @@
 import errno
 import multiprocessing
 import os
-import Queue
+import queue
 import re
 import shutil
 import subprocess
@@ -68,7 +68,7 @@
       os.close(fd)
   try:
     j2objc_cmd = [java]
-    j2objc_cmd.extend(filter(None, jvm_flags.split(',')))
+    j2objc_cmd.extend([_f for _f in jvm_flags.split(',') if _f])
     j2objc_cmd.extend(['-cp', j2objc, main_class])
     j2objc_cmd.extend(['@%s' % param_filename])
     subprocess.check_call(j2objc_cmd, stderr=subprocess.STDOUT)
@@ -100,13 +100,13 @@
     None.
   """
   dep_mapping = dict()
-  input_file_queue = Queue.Queue()
-  output_dep_mapping_queue = Queue.Queue()
-  error_message_queue = Queue.Queue()
+  input_file_queue = queue.Queue()
+  output_dep_mapping_queue = queue.Queue()
+  error_message_queue = queue.Queue()
   for objc_file in objc_files:
     input_file_queue.put(os.path.join(objc_file_root, objc_file))
 
-  for _ in xrange(multiprocessing.cpu_count()):
+  for _ in range(multiprocessing.cpu_count()):
     t = threading.Thread(target=_ReadDepMapping, args=(input_file_queue,
                                                        output_dep_mapping_queue,
                                                        error_message_queue,
@@ -136,7 +136,7 @@
   while True:
     try:
       input_file = input_file_queue.get_nowait()
-    except Queue.Empty:
+    except queue.Empty:
       # No more work left in the queue.
       return
 
--- a/tools/objc/j2objc_dead_code_pruner.py
+++ b/tools/objc/j2objc_dead_code_pruner.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python2.7
+#!/usr/bin/python3
 
 # Copyright 2015 The Bazel Authors. All rights reserved.
 #
@@ -29,15 +29,13 @@
 from collections import OrderedDict
 import multiprocessing
 import os
-import pipes  # swap to shlex once on Python 3
+import shlex as pipes
+import queue
 import re
 import shutil
 import subprocess
 import threading
 
-from six.moves import queue as Queue  # pylint: disable=redefined-builtin
-from six.moves import xrange  # pylint: disable=redefined-builtin
-
 PRUNED_SRC_CONTENT = 'static int DUMMY_unused __attribute__((unused,used)) = 0;'
 
 
@@ -164,12 +162,12 @@
   Returns:
     None.
   """
-  file_queue = Queue.Queue()
+  file_queue = queue.Queue()
   for input_file, output_file in zip(input_files.split(','),
                                      output_files.split(',')):
     file_queue.put((input_file, output_file))
 
-  for _ in xrange(multiprocessing.cpu_count()):
+  for _ in range(multiprocessing.cpu_count()):
     t = threading.Thread(target=_PruneFile, args=(file_queue,
                                                   reachable_files,
                                                   objc_file_path,
@@ -185,7 +183,7 @@
   while True:
     try:
       input_file, output_file = file_queue.get_nowait()
-    except Queue.Empty:
+    except queue.Empty:
       return
     file_name = os.path.relpath(os.path.splitext(input_file)[0],
                                 objc_file_path)
@@ -211,7 +209,7 @@
   duplicated_files = []
   dict_with_duplicates = dict()
 
-  for source_files in archive_source_file_mapping.values():
+  for source_files in list(archive_source_file_mapping.values()):
     for source_file in source_files:
       file_basename = os.path.basename(source_file)
       file_without_ext = os.path.splitext(source_file)[0]