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Catch syntax errors in nested interpolations before Python 3.12 #20949

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Catch syntax errors in nested interpolations before Python 3.12 #20949

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1522d87
Catch syntax errors in nested interpolations before Python 3.12
ntBre Oct 17, 2025
774c415
add failing tests
ntBre Oct 17, 2025
2999db4
pass the tests
ntBre Oct 17, 2025
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4 changes: 4 additions & 0 deletions crates/ruff_python_parser/resources/inline/err/pep701_nested_interpolation_py311.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
# parse_options: {"target-version": "3.11"}
# nested interpolations also need to be checked
f'{1: abcd "{'aa'}" }'
f'{1: abcd "{"\n"}" }'
196 changes: 100 additions & 96 deletions crates/ruff_python_parser/src/parser/expression.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1539,103 +1539,9 @@ impl<'src> Parser<'src> {
flags = flags.with_unclosed(true);
}

// test_ok pep701_f_string_py312
// # parse_options: {"target-version": "3.12"}
// f'Magic wand: { bag['wand'] }' # nested quotes
// f"{'\n'.join(a)}" # escape sequence
// f'''A complex trick: {
// bag['bag'] # comment
// }'''
// f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" # arbitrary nesting
// f"{f'''{"nested"} inner'''} outer" # nested (triple) quotes
// f"test {a \
// } more" # line continuation

// test_ok pep750_t_string_py314
// # parse_options: {"target-version": "3.14"}
// t'Magic wand: { bag['wand'] }' # nested quotes
// t"{'\n'.join(a)}" # escape sequence
// t'''A complex trick: {
// bag['bag'] # comment
// }'''
// t"{t"{t"{t"{t"{t"{1+1}"}"}"}"}"}" # arbitrary nesting
// t"{t'''{"nested"} inner'''} outer" # nested (triple) quotes
// t"test {a \
// } more" # line continuation

// test_ok pep701_f_string_py311
// # parse_options: {"target-version": "3.11"}
// f"outer {'# not a comment'}"
// f'outer {x:{"# not a comment"} }'
// f"""{f'''{f'{"# not a comment"}'}'''}"""
// f"""{f'''# before expression {f'# aro{f"#{1+1}#"}und #'}'''} # after expression"""
// f"escape outside of \t {expr}\n"
// f"test\"abcd"
// f"{1:\x64}" # escapes are valid in the format spec
// f"{1:\"d\"}" # this also means that escaped outer quotes are valid

// test_err pep701_f_string_py311
// # parse_options: {"target-version": "3.11"}
// f'Magic wand: { bag['wand'] }' # nested quotes
// f"{'\n'.join(a)}" # escape sequence
// f'''A complex trick: {
// bag['bag'] # comment
// }'''
// f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" # arbitrary nesting
// f"{f'''{"nested"} inner'''} outer" # nested (triple) quotes
// f"test {a \
// } more" # line continuation
// f"""{f"""{x}"""}""" # mark the whole triple quote
// f"{'\n'.join(['\t', '\v', '\r'])}" # multiple escape sequences, multiple errors

// test_err nested_quote_in_format_spec_py312
// # parse_options: {"target-version": "3.12"}
// f"{1:""}" # this is a ParseError on all versions

// test_ok non_nested_quote_in_format_spec_py311
// # parse_options: {"target-version": "3.11"}
// f"{1:''}" # but this is okay on all versions
let range = self.node_range(start);

if !self.options.target_version.supports_pep_701()
&& matches!(kind, InterpolatedStringKind::FString)
{
let quote_bytes = flags.quote_str().as_bytes();
let quote_len = flags.quote_len();
for expr in elements.interpolations() {
// We need to check the whole expression range, including any leading or trailing
// debug text, but exclude the format spec, where escapes and escaped, reused quotes
// are allowed.
let range = expr
.format_spec
.as_ref()
.map(|format_spec| TextRange::new(expr.start(), format_spec.start()))
.unwrap_or(expr.range);
for slash_position in memchr::memchr_iter(b'\\', self.source[range].as_bytes()) {
let slash_position = TextSize::try_from(slash_position).unwrap();
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::Pep701FString(FStringKind::Backslash),
TextRange::at(range.start() + slash_position, '\\'.text_len()),
);
}

if let Some(quote_position) =
memchr::memmem::find(self.source[range].as_bytes(), quote_bytes)
{
let quote_position = TextSize::try_from(quote_position).unwrap();
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::Pep701FString(FStringKind::NestedQuote),
TextRange::at(range.start() + quote_position, quote_len),
);
}
}

self.check_fstring_comments(range);
}

InterpolatedStringData {
elements,
range,
range: self.node_range(start),
flags,
}
}
Expand Down Expand Up @@ -1921,12 +1827,110 @@ impl<'src> Parser<'src> {
);
}

// test_ok pep701_f_string_py312
// # parse_options: {"target-version": "3.12"}
// f'Magic wand: { bag['wand'] }' # nested quotes
// f"{'\n'.join(a)}" # escape sequence
// f'''A complex trick: {
// bag['bag'] # comment
// }'''
// f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" # arbitrary nesting
// f"{f'''{"nested"} inner'''} outer" # nested (triple) quotes
// f"test {a \
// } more" # line continuation

// test_ok pep750_t_string_py314
// # parse_options: {"target-version": "3.14"}
// t'Magic wand: { bag['wand'] }' # nested quotes
// t"{'\n'.join(a)}" # escape sequence
// t'''A complex trick: {
// bag['bag'] # comment
// }'''
// t"{t"{t"{t"{t"{t"{1+1}"}"}"}"}"}" # arbitrary nesting
// t"{t'''{"nested"} inner'''} outer" # nested (triple) quotes
// t"test {a \
// } more" # line continuation

// test_ok pep701_f_string_py311
// # parse_options: {"target-version": "3.11"}
// f"outer {'# not a comment'}"
// f'outer {x:{"# not a comment"} }'
// f"""{f'''{f'{"# not a comment"}'}'''}"""
// f"""{f'''# before expression {f'# aro{f"#{1+1}#"}und #'}'''} # after expression"""
// f"escape outside of \t {expr}\n"
// f"test\"abcd"
// f"{1:\x64}" # escapes are valid in the format spec
// f"{1:\"d\"}" # this also means that escaped outer quotes are valid

// test_err pep701_f_string_py311
// # parse_options: {"target-version": "3.11"}
// f'Magic wand: { bag['wand'] }' # nested quotes
// f"{'\n'.join(a)}" # escape sequence
// f'''A complex trick: {
// bag['bag'] # comment
// }'''
// f"{f"{f"{f"{f"{f"{1+1}"}"}"}"}"}" # arbitrary nesting
// f"{f'''{"nested"} inner'''} outer" # nested (triple) quotes
// f"test {a \
// } more" # line continuation
// f"""{f"""{x}"""}""" # mark the whole triple quote
// f"{'\n'.join(['\t', '\v', '\r'])}" # multiple escape sequences, multiple errors

// test_err pep701_nested_interpolation_py311
// # parse_options: {"target-version": "3.11"}
// # nested interpolations also need to be checked
// f'{1: abcd "{'aa'}" }'
// f'{1: abcd "{"\n"}" }'

// test_err nested_quote_in_format_spec_py312
// # parse_options: {"target-version": "3.12"}
// f"{1:""}" # this is a ParseError on all versions

// test_ok non_nested_quote_in_format_spec_py311
// # parse_options: {"target-version": "3.11"}
// f"{1:''}" # but this is okay on all versions
let range = self.node_range(start);

if !self.options.target_version.supports_pep_701()
&& matches!(string_kind, InterpolatedStringKind::FString)
{
// We need to check the whole expression range, including any leading or trailing
// debug text, but exclude the format spec, where escapes and escaped, reused quotes
// are allowed.
let range = format_spec
.as_ref()
.map(|format_spec| TextRange::new(range.start(), format_spec.start()))
.unwrap_or(range);

let quote_bytes = flags.quote_str().as_bytes();
let quote_len = flags.quote_len();
for slash_position in memchr::memchr_iter(b'\\', self.source[range].as_bytes()) {
let slash_position = TextSize::try_from(slash_position).unwrap();
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::Pep701FString(FStringKind::Backslash),
TextRange::at(range.start() + slash_position, '\\'.text_len()),
);
}

if let Some(quote_position) =
memchr::memmem::find(self.source[range].as_bytes(), quote_bytes)
{
let quote_position = TextSize::try_from(quote_position).unwrap();
self.add_unsupported_syntax_error(
UnsupportedSyntaxErrorKind::Pep701FString(FStringKind::NestedQuote),
TextRange::at(range.start() + quote_position, quote_len),
);
}

self.check_fstring_comments(range);
}

ast::InterpolatedElement {
expression: Box::new(value.expr),
debug_text,
conversion,
format_spec,
range: self.node_range(start),
range,
node_index: AtomicNodeIndex::NONE,
}
}
Expand Down
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