[3.12] gh-111609: end_offset is ignored in subclasses of SyntaxError

[nineteendo]

Example:

class CustomSyntaxError(SyntaxError):
    pass

raise CustomSyntaxError("Error message", (None, 1, 5, 'a = sin(3)', 1, 9))

main:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    a = sin(3)
        ^
CustomSyntaxError: Error message

PR:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    a = sin(3)
        ^^^^
CustomSyntaxError: Error message

• Issue: end_offset is ignored in subclasses of SyntaxError (3.12-only) #111609

[nineteendo]

@pablogsal, do you remember why this check was added in #25525? This works fine:

>>> class CustomSyntaxError(SyntaxError):
...     def __init__(self, msg, filename, lineno, offset, text, end_lineno, end_offset):
...         self.msg = msg
...         self.filename = filename
...         self.lineno = lineno
...         self.offset = offset
...         self.text = text
...         # self.end_lineno = end_lineno
...         # self.end_offset = end_offset
... 
>>> raise CustomSyntaxError("Error message", None, 1, 5, 'a = sin(3)', 1, 9)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    a = sin(3)
        ^
CustomSyntaxError: Error message

[pablogsal]

do you remember why this check was added in

What check are you referring to? The subclass check? IIRC is because some people were using some subclasses of syntax errors that were yielding weird results when displayed but I searched for the conversation and could not find anything :S

[pablogsal]

Can we also add this test to main if is not there already?

[nineteendo]

I created a PR: #127830

[pablogsal]

LGTM

Thanks for the catch @nineteendo!