File foo3.py is [cut down (orig 87Kb)] output of 2to3 conversion tool
and (coincidentally) is still valid 2.x syntax. There are no syntax
errors reported by any of the following:
\python26\python -c "import foo3"
\python26\python foo3.py
\python26\python setup.py install
\python30\python -c "import foo3"
\python30\python foo3.py
However 3.0 install
\python30\python setup.py install
produces:
"""
[snip]
running install_lib
copying build\lib\foo3.py -> C:\python30\Lib\site-packages
byte-compiling C:\python30\Lib\site-packages\foo3.py to foo3.pyc
File "C:\python30\Lib\site-packages\foo3.py", line 0
### Note also "line 0" above ###
SyntaxError: unknown encoding: cp1252
"""
Same happens if alternative name windows-1252 is used instead of cp1252.

NOTE: file foo3.py actually does have some non-ASCII characters (\xa0,
\x93, \x94), in comments. Another file (bar3.py) from the same package
contains \xb7 twice, but doesn't have the unknown encoding problem.
There are several other files in the same package that start with "# --
coding: windows-1252 --" (or cp1252, or even cp1251(!)) but have no
non-ASCII characters in them. They don't get this incorrect error
message either.

A clue:

>>> print(ascii(b'\xa0\x93\x94\xb7'.decode('cp1252')))
'\xa0\u201c\u201d\xb7'

Could be that it only happens where there's a cp1252 character that's
not in latin1; see files x93.py and x94.py (have problem) and xa0b7.py
(doesn't have problem).

Here's a status:

The problem is located in the codec that decodes the data (called by the
compile builtin).

It throws an error :

*** UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in
position 853: character maps to <undefined>

Which is caught by compile and translated into:

SyntaxError: unknown encoding: cp1252

So I see two problems:

1/ why compile throws such an error when there's an UnicodeDecodeError
2/ why compile works well under Py2 since 0x9d is not part of the
cp1252 mapping

I have written a test that reproduces the problem, and I am still
investigating. If I can't find the problem I will ask for help on
python-dev because I have no knowledge in the compiler internals yet.

TWO POINTS:
(1) I am not very concerned about chars like \x9d which are not valid in
the declared encoding; I am more concerned with chars like \x93 and \x94
which *ARE* valid in the declared encoding. Please ensure that these
cases are included in tests.
(2) Please check your test data and test results. I get different
results. I have created a file x9d.py by making the minimal changes to
x94.py. For me, this blows up on bytecompiling with *both* 3.0
(UnicodeDecodeError, as expected) and 2.x (Syntax Error unknown encoding
cp1252, wrong message) -- see below.

byte-compiling C:\python30\Lib\site-packages\x9d.py to x9d.pyc
Traceback (most recent call last):
  File "setup.py", line 5, in <module>
    py_modules = ["foo3", "bar3", "x93", "x94", "x9d", "xa0b7"]
  File "C:\python30\lib\distutils\core.py", line 149, in setup
    dist.run_commands()
  File "C:\python30\lib\distutils\dist.py", line 942, in run_commands
    self.run_command(cmd)
  File "C:\python30\lib\distutils\dist.py", line 962, in run_command
    cmd_obj.run()
  File "C:\python30\lib\distutils\command\install.py", line 571, in run
    self.run_command(cmd_name)
  File "C:\python30\lib\distutils\cmd.py", line 317, in run_command
    self.distribution.run_command(command)
  File "C:\python30\lib\distutils\dist.py", line 962, in run_command
    cmd_obj.run()
  File "C:\python30\lib\distutils\command\install_lib.py", line 91, in run
    self.byte_compile(outfiles)
  File "C:\python30\lib\distutils\command\install_lib.py", line 125, in
byte_compile
    dry_run=self.dry_run)
  File "C:\python30\lib\distutils\util.py", line 520, in byte_compile
    compile(file, cfile, dfile)
  File "C:\python30\lib\py_compile.py", line 137, in compile
    codestring = f.read()
  File "C:\python30\lib\io.py", line 1724, in read
    decoder.decode(self.buffer.read(), final=True))
  File "C:\python30\lib\io.py", line 1295, in decode
    output = self.decoder.decode(input, final=final)
  File "C:\python30\lib\encodings\cp1252.py", line 23, in decode
    return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x9d in position
64: character maps to <undefined>

byte-compiling C:\python26\Lib\site-packages\x9d.py to x9d.pyc
SyntaxError: ('unknown encoding: cp1252',
('C:\\python26\\Lib\\site-packages\\x9d.py', 0, 0, None))

byte-compiling c:\python25\Lib\site-packages\x9d.py to x9d.pyc
File "c:\python25\Lib\site-packages\x9d.py", line 0
SyntaxError: ('unknown encoding: cp1252',
('c:\\python25\\Lib\\site-packages\\x9d.py', 0, 0, None))

On 2008-12-30 13:20, John Machin wrote:

byte-compiling C:\python26\Lib\site-packages\x9d.py to x9d.pyc
SyntaxError: ('unknown encoding: cp1252',
('C:\\python26\\Lib\\site-packages\\x9d.py', 0, 0, None))

byte-compiling c:\python25\Lib\site-packages\x9d.py to x9d.pyc
File "c:\python25\Lib\site-packages\x9d.py", line 0
SyntaxError: ('unknown encoding: cp1252',
('c:\\python25\\Lib\\site-packages\\x9d.py', 0, 0, None))

Added file: http://bugs.python.org/file12492/x9d.py

FWIW, I've tried that file with Python 2.5 and 2.6 on my machine:

lemburg/tmp> python2.5 ~/bin/pycompile.py x9d.py
compiling x9d.py -> x9d.pyc
XXX <type 'exceptions.SyntaxError'>: unknown encoding: cp1252 (x9d.py, line 0)

lemburg/tmp> python2.6 ~/bin/pycompile.py x9d.py
compiling x9d.py -> x9d.pyc
XXX <type 'exceptions.SyntaxError'>: unknown encoding: cp1252 (x9d.py, line 0)

Note that the line number is wrong in both messages.

It is interesting that simply running the files gives a more correct
error message:

lemburg/tmp> python2.5 x9d.py
File "x9d.py", line 2
SyntaxError: 'charmap' codec can't decode byte 0x9d in position 0: character
maps to <undefined>

lemburg/tmp> python2.6 x9d.py
File "x9d.py", line 2
SyntaxError: 'charmap' codec can't decode byte 0x9d in position 0: character
maps to <undefined>

The character position is wrong again in both messages.

Needless to say that the encoding "cp1252" is *not* unknown. It looks
like compile() causes the decoding error to be overwritten with a
misleading error message.

yup, here's the test I have written to demonstrate the problem. In any
case, compile doesn't behave right way in the first place.

(1) what am I supposed to infer from "Yup"?? That all of that \x9d stuff
was a mistake?

(2)
+ def tearDown(self):
+ pyc_file = os.path.join(os.path.dirname(file), 'cp1252.pyc')
+ if os.path.exists(pyc_file):
+ os.patth.remove(pyc_file)

os.patth is novel :-)

This is a duplicate of bpo-4626.

Here, the content is correctly decoded with cp1252, then passed to
compile(); but compile() works on the internal utf-8 representation, and
tries to decode it again with cp1252!

Yes, the error message is overwritten. If I remove the code that sets
the "unknown encoding" exception, I get:

>>> compile(open("c:/temp/t1252.py", encoding="cp1252").read(),
"t1252.py", "exec")
SyntaxError: 'charmap' codec can't decode byte 0x9d in position 35:
character maps to <undefined>

The 0x9d explains easily:
>>> b"\x94".decode('cp1252').encode('utf8')
b'\xe2\x80\x9d'