Update doctect SyntaxErrors for location range

[akulakov]

BPO	45249
Nosy	@terryjreedy, @blueyed, @pablogsal, @miss-islington, @Fidget-Spinner, @akulakov
PRs	bpo-45249: Add regression test for display of SyntaxError range indicator in doctests #28567 bpo-45249: Ensure the traceback module prints correctly syntax errors with ranges #28575 [3.10] bpo-45249: Ensure the traceback module prints correctly syntax errors with ranges (GH-28575) #28587 bpo-45249: Fix caret location when end_offset is set to 0 #28854 bpo-45249: Fix caret location when end_offset is set to 0 #28855 [3.10] bpo-45249: Fix caret location when end_offset is set to 0 (GH-28855) #28994

^{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 = None
closed_at = <Date 2021-10-16.17:37:28.444>
created_at = <Date 2021-09-20.16:30:58.559>
labels = ['type-bug', 'library', '3.10', '3.11']
title = 'Update doctect SyntaxErrors for location range'
updated_at = <Date 2021-10-16.17:51:11.950>
user = 'https://github.com/akulakov'

bugs.python.org fields:

activity = <Date 2021-10-16.17:51:11.950>
actor = 'miss-islington'
assignee = 'none'
closed = True
closed_date = <Date 2021-10-16.17:37:28.444>
closer = 'pablogsal'
components = ['Library (Lib)']
creation = <Date 2021-09-20.16:30:58.559>
creator = 'andrei.avk'
dependencies = []
files = []
hgrepos = []
issue_num = 45249
keywords = ['patch']
message_count = 18.0
messages = ['402257', '402258', '402260', '402263', '402268', '402269', '402271', '402284', '402589', '402652', '402662', '402670', '402739', '402742', '403157', '403588', '404103', '404106']
nosy_count = 6.0
nosy_names = ['terry.reedy', 'blueyed', 'pablogsal', 'miss-islington', 'kj', 'andrei.avk']
pr_nums = ['28567', '28575', '28587', '28854', '28855', '28994']
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue45249'
versions = ['Python 3.10', 'Python 3.11']

Linked PRs

• gh-89412: Add missing attributes (added in 3.10) to traceback module docs #105046
• [3.12] gh-89412: Add missing attributes (added in 3.10) to traceback module docs (GH-105046) #105327
• [3.11] gh-89412: Add missing attributes (added in 3.10) to traceback module docs (GH-105046) #105328
• [3.10] gh-89412: Add missing attributes (added in 3.10) to traceback module docs (GH-105046) #105329

[akulakov]

It seems like fine grained error locations do not work in failed doctest traceback output:

version 3.11.0a0

file contents:
------------------

def a(x):
    """
    >>> 1 1
    1
    """
import doctest
doctest.testmod()

OUTPUT
-------

Failed example:
    1 1
Exception raised:
    Traceback (most recent call last):
      File "/Users/ak/opensource/cpython/Lib/doctest.py", line 1348, in __run
        exec(compile(example.source, filename, "single",
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "<doctest __main__.a[0]>", line 1
        1 1
        ^
    SyntaxError: invalid syntax. Perhaps you forgot a comma?

The location in doctests that causes this:

cpython/Lib/doctest.py

Line 1348 in 5846c9b

exec(compile(example.source, filename, "single",

[akulakov]

I've ran into this when looking at doctest docs, the issue is that they use the old example where a single column is highlighted, I want to update it to explain why doctest output differs from the one you get from REPL, but I probably need to understand why it happens to provide a good explanation.

Alternatively this may be fixed to be consistent if it's easy enough to do.

[pablogsal]

Hummmm, could you explain a bit more in detail what is the expected output? I can see highlighting in the exec call that you pasted:

    exec(compile(example.source, filename, "single",
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The fact that you see those "^^^^^^" indicate that is working no? What is missing?

[akulakov]

Sorry, I should have noted I’m referring to the line 1 1
Which is underlined by a single caret, but on the command line it has 3
carets as expected.

[pablogsal]

Ah, but that is a different issue. This is not PEP-657, this is a SyntaxError, so is related how those are printed, which I think is separared.

[pablogsal]

Can you try a doctest that fails on something that is not a SyntaxError.

Something like:

>>> def foo(x):
...    return x + 42

>> foo(None)

[akulakov]

Pablo: that works fine, thanks!

I will look into updating the doctest docs, and will close this issue later
today ( or you can close it if you like).