[Python-checkins] bpo-44666: Use default encoding as fallback for compile_file (GH-27236) (GH-27489)

[ambv]

https://github.com/python/cpython/commit/73240d425b770c26d9424665259cd9a2f339b626
commit: 73240d425b770c26d9424665259cd9a2f339b626
branch: 3.9
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: ambv <lukasz at langa.pl>
date: 2021-07-30T19:12:29+02:00
summary:

bpo-44666: Use default encoding as fallback for compile_file (GH-27236) (GH-27489)

When sys.stdout.encoding is None compile_file will fall back to
sys.getdefaultencoding to encode/decode error messages.

Co-authored-by: Stefan Hoelzl <stefan.hoelzl at posteo.de>
Co-authored-by: Mickaël Schoentgen <contact at tiger-222.fr>
(cherry picked from commit 80f07076294bc09a55ed76d9bbf307404eef25e6)

files:
A Misc/NEWS.d/next/Library/2021-07-21-10-43-22.bpo-44666.CEThkv.rst
M Lib/compileall.py
M Lib/test/test_compileall.py
M Misc/ACKS

diff --git a/Lib/compileall.py b/Lib/compileall.py
index fe7f450c55e1c..33fb76c541544 100644
--- a/Lib/compileall.py
+++ b/Lib/compileall.py
@@ -252,9 +252,8 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=0,
                 else:
                     print('*** ', end='')
                 # escape non-printable characters in msg
-                msg = err.msg.encode(sys.stdout.encoding,
-                                     errors='backslashreplace')
-                msg = msg.decode(sys.stdout.encoding)
+                encoding = sys.stdout.encoding or sys.getdefaultencoding()
+                msg = err.msg.encode(encoding, errors='backslashreplace').decode(encoding)
                 print(msg)
             except (SyntaxError, UnicodeError, OSError) as e:
                 success = False
diff --git a/Lib/test/test_compileall.py b/Lib/test/test_compileall.py
index 3bbc6817f8d56..8df705666c092 100644
--- a/Lib/test/test_compileall.py
+++ b/Lib/test/test_compileall.py
@@ -164,6 +164,14 @@ def test_no_pycache_in_non_package(self):
         compileall.compile_file(data_file)
         self.assertFalse(os.path.exists(os.path.join(data_dir, '__pycache__')))
 
+
+    def test_compile_file_encoding_fallback(self):
+        # Bug 44666 reported that compile_file failed when sys.stdout.encoding is None
+        self.add_bad_source_file()
+        with contextlib.redirect_stdout(io.StringIO()):
+            self.assertFalse(compileall.compile_file(self.bad_source_path))
+
+
     def test_optimize(self):
         # make sure compiling with different optimization settings than the
         # interpreter's creates the correct file names
diff --git a/Misc/ACKS b/Misc/ACKS
index f01cc5d970bb7..fc5602d39b65a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -781,6 +781,7 @@ Fredrik Håård
 Florian Höch
 Oleg Höfling
 Robert Hölzl
+Stefan Hölzl
 Catalin Iacob
 Mihai Ibanescu
 Ali Ikinci
diff --git a/Misc/NEWS.d/next/Library/2021-07-21-10-43-22.bpo-44666.CEThkv.rst b/Misc/NEWS.d/next/Library/2021-07-21-10-43-22.bpo-44666.CEThkv.rst
new file mode 100644
index 0000000000000..ab2ef22d0c455
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-07-21-10-43-22.bpo-44666.CEThkv.rst
@@ -0,0 +1,2 @@
+Fixed issue in :func:`compileall.compile_file` when ``sys.stdout`` is redirected.
+Patch by Stefan Hölzl.