Python 3 pdb: shows internal code, breakpoints don't work

[ericp]

BPO	6126
Nosy	@birkenfeld, @pitrou, @agronholm
Files	pdb-fix.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/birkenfeld'
closed_at = <Date 2009-08-13.08:17:21.997>
created_at = <Date 2009-05-27.19:15:05.953>
labels = ['interpreter-core', 'type-bug']
title = "Python 3 pdb: shows internal code, breakpoints don't work"
updated_at = <Date 2009-08-13.08:17:21.996>
user = 'https://bugs.python.org/ericp'

bugs.python.org fields:

activity = <Date 2009-08-13.08:17:21.996>
actor = 'georg.brandl'
assignee = 'georg.brandl'
closed = True
closed_date = <Date 2009-08-13.08:17:21.997>
closer = 'georg.brandl'
components = ['Interpreter Core']
creation = <Date 2009-05-27.19:15:05.953>
creator = 'ericp'
dependencies = []
files = ['14679']
hgrepos = []
issue_num = 6126
keywords = ['patch']
message_count = 7.0
messages = ['88431', '88756', '91433', '91434', '91468', '91469', '91515']
nosy_count = 4.0
nosy_names = ['georg.brandl', 'pitrou', 'ericp', 'alex.gronholm']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue6126'
versions = ['Python 3.0']

[ericp]

I have a simple test file, test01.py, with this output:
$ cat test01.py
#!/usr/bin/env python

print("Line 1")
print("Line 2")
print("Line 3")
$
$ # Now try debugging it.
$ python3.0 -mpdb test01.py
--Return--
> /home/ericp/opt/Python-3.0.1/lib/python3.0/io.py(762)closed()->False
-> return self.raw.closed
(Pdb) b test01.py:4
Breakpoint 1 at /home/ericp/lab/Python-3.0.1/test01.py:5
(Pdb) r
--Return--
> /home/ericp/opt/Python-3.0.1/lib/python3.0/io.py(1471)closed()->False
-> return self.buffer.closed
(Pdb) c
line 1
line 2
line 3
The program finished and will be restarted

Two main problems:

1. I shouldn't see the code for io.py

2. The program doesn't stop at the breakpoint, because that
   stack frame is exposed to bdb as (file:"<string>", line:4),
   not (file:"/home/.../test01.py", line:4).

[ericp]

Similar problem with 3.1rc1:

C:\...>c:\Python31rc1\python.exe -m pdb hello01.py
--Return--

c:\python31rc1\lib\encodings\cp437.py(19)encode()->b'Hello'
-> return codecs.charmap_encode(input,self.errors,encoding_map)[0]
(Pdb) b 2
*** Blank or comment
(Pdb) b hello01.py:2
Breakpoint 1 at c:\...\hello01.py:2

(Pdb) b
Num Type Disp Enb Where
1 breakpoint keep yes at c:\...\hello01.py:2
(Pdb) c
Hello
here
bye
The program finished and will be restarted
--Return--

c:\python31rc1\lib\encodings\cp437.py(19)encode()->b'Hello'
-> return codecs.charmap_encode(input,self.errors,encoding_map)[0]
(Pdb)

[agronholm]

Why has this not been resolved yet? Not having a working debugger is a
severe hindrance to the acceptance of Py3k.

[birkenfeld]

Attached patch confirmedly fixes this. Will commit as soon as svn is
back up.

[pitrou]

Reading this patch, is it normal that the file is opened in text mode
without an encoding specified? What if the source file uses a different
encoding than the default system one?

[birkenfeld]

That's a good question :)

A quick test shows that exec() does honor coding cookies in code given
as a bytestring, so simply changing to open(..., "rb") should be fine.

[birkenfeld]

Fixed in r74366, and merged back to 3.1 branch in r74367.