Terry J. Reedy <tjre...@udel.edu> added the comment:
In 3.10+, end_lineno and end_offset fields were added to SyntaxError objects
and the args tuple.
>>> try: compile('1 1', '', 'single')
... except SyntaxError as e: print(e.args)
...
('invalid syntax. Perhaps you forgot a comma?', ('', 1, 1, '1 1', 1, 4))
Here, line 1, offset 4 is the first 1-based column not part of the error.
The builtin default sys.excepthook was modified to read and use this new
information and mark (end_offset - offset) columns with '^'s. This default
prints what it does to sys.stderr.
The syntax error formatting in the traceback module was not altered. However,
a new method, TracebackException._format_syntax_error, was extracted from
TracebackException.format_exception_only so that the former could be overridden
by software that simulates interaction.
The printed traceback does not come from line 1348. That *executes* the user
code, but all Exceptions, including SyntaxError, are caught. If the exception
is not expected and the run is not quiet, the exception is output by
report_unexpected_exception(), as seen above as 'OUTPUT' and the lines that
follows.
https://github.com/python/cpython/blob/5846c9b71ee9277fe866b1bdee4cc6702323fe7e/Lib/doctest.py#L1264
This calls _exception_traceback(exc_info).
https://github.com/python/cpython/blob/5846c9b71ee9277fe866b1bdee4cc6702323fe7e/Lib/doctest.py#L244
This calls traceback.print_exception, which I believe, for syntax errors,
ultimately calls TracebackException._format_syntax_error.
I believe that the options for a fix are either
1. Call default sys.excepthook while capturing its output into a StringIO
instance.
2. Assuming I am correct above about _format_syntax_error being called,
monkeypatch it. In line 779,
https://github.com/python/cpython/blob/5846c9b71ee9277fe866b1bdee4cc6702323fe7e/Lib/traceback.py#L779
replace '^' with a field with a calculated number of ^s.
I need to do one of these two for IDLE, and may try both.
----------
components: +Library (Lib) -Interpreter Core, Tests
nosy: +terry.reedy
stage: -> needs patch
title: SyntaxError location range indicator does not work in doctests -> Update
doctect SyntaxErrors for location range
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<https://bugs.python.org/issue45249>
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