[New-bugs-announce] [issue43600] IDLE: fix highlight locationfor f-string field errors

[Terry J. Reedy]

New submission from Terry J. Reedy <tjreedy at udel.edu>:

Spinoff from #41064.  In current python, the f'{*x}' traceback ends with 

    (*x)
     ^
SyntaxError: f-string: can't use starred expression here.

For f'{**x}', the message is "f-string: invalid syntax" and the ^ is also under the 2nd character in the replacement expression actually parsed (with a restricted grammar).

The Python error handler must special case a syntax error message beginning with 'f-string:' and search the input line for {...} and add its offset.

IDLE currently highlights "'", the 2nd char of the original code, instead of '*', the 2nd char of the e.text replacement.  It needs to also adjust the offset.

----------
assignee: terry.reedy
components: IDLE
messages: 389365
nosy: terry.reedy
priority: normal
severity: normal
stage: test needed
status: open
title: IDLE: fix highlight locationfor f-string field errors
type: behavior
versions: Python 3.10, Python 3.8, Python 3.9

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43600>
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