[issue3684] traceback.format_exception_only() misplaces the caret for certain SyntaxErrors

[Brodie Rao]

New submission from Brodie Rao <junk at dackz.net>:

>> +
  File "<stdin>", line 1
    +
    ^
SyntaxError: invalid syntax
>>> import sys
>>> import traceback
>>> traceback.print_exception(sys.last_type, sys.last_value, None)
  File "<stdin>", line 1
     +
     
^
 SyntaxError: invalid syntax
>>> sys.last_value
SyntaxError('invalid syntax', ('<stdin>', 1, 2, '+\n'))

print_error_text() effectively ignores trailing newlines when placing 
the caret, while traceback.format_exception_only() does not. For certain 
syntax errors the offset reported is sometimes at the newline, as in the 
case of a line of code that ends just with a plus sign (and in other 
similar cases).

I'm attaching a patch for trunk that fixes this issue. I know it also 
affects Python 2.5, and I'm sure it affects versions prior. I don't know 
about Python 3.0.

----------
components: Library (Lib)
files: traceback-caret.patch
keywords: patch
messages: 71967
nosy: brodierao
severity: normal
status: open
title: traceback.format_exception_only() misplaces the caret for certain SyntaxErrors
type: behavior
Added file: http://bugs.python.org/file11260/traceback-caret.patch

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