New submission from Arminius <numir...@gmail.com>:
ast.parse() will give a wrong code position for an expression inside an
f-string when the expression is using a format specifier.
Compare the trees of f'{a}' and f'{a:b}' :
>>> ast.parse("f'{a}'")
Module(
body=[
Expr(
lineno=1,
col_offset=0,
value=JoinedStr(
lineno=1,
col_offset=0,
values=[
FormattedValue(
lineno=1,
col_offset=0,
value=Name(lineno=1, col_offset=3, id='a', ctx=Load()),
conversion=-1,
format_spec=None,
),
],
),
),
],
)
>>> ast.parse("f'{a:b}'")
Module(
body=[
Expr(
lineno=1,
col_offset=0,
value=JoinedStr( col_offset=0,
lineno=1,
col_offset=0,
values=[
FormattedValue(
lineno=1,
col_offset=0,
value=Name(lineno=1, col_offset=1, id='a', ctx=Load()),
conversion=-1,
format_spec=JoinedStr(
lineno=1,
col_offset=0,
values=[Str(lineno=1, col_offset=0, s='b')],
),
),
],
),
),
],
)
In both examples, the name "a" is at the same position in the source code,
however the parsed ASTs yield two different offsets,
Name(lineno=1, col_offset=3, id='a', ctx=Load())
and
Name(lineno=1, col_offset=1, id='a', ctx=Load())
.
Expected behavior: col_offset=3 for name "a" in both f-strings.
(In my specific use case, this breaks a semantic highlighting plugin for vim.)
----------
components: Interpreter Core
messages: 329672
nosy: arminius
priority: normal
severity: normal
status: open
title: Expressions with format specifiers in f-strings give wrong code position
in AST
type: behavior
versions: Python 3.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue35212>
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