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Merged
MichaReiser merged 3 commits into from
Jun 18, 2025
Merged

Disallow newlines in format specifiers of single quoted f- or t-strings #18708

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6a420de
Disallow newlines in format specifiers of sinlge quoted f- or t-strings
MichaReiser Jun 16, 2025
a17c486
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MichaReiser Jun 16, 2025
b9ba5fe
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MichaReiser Jun 18, 2025
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3 changes: 1 addition & 2 deletions crates/ruff_python_formatter/resources/test/fixtures/black/cases/pep_701.py
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Original file line number Diff line number Diff line change
Expand Up @@ -74,8 +74,7 @@
f'{(abc:=10)}'

f"This is a really long string, but just make sure that you reflow fstrings {
2+2:d
}"
2+2:d}"
f"This is a really long string, but just make sure that you reflow fstrings correctly {2+2:d}"

f"{2+2=}"
Expand Down
31 changes: 13 additions & 18 deletions crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/fstring.py
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Expand Up @@ -278,23 +278,21 @@

# Combine conversion flags with format specifiers
x = f"{x = !s
:>0

}"
# This is interesting. There can be a comment after the format specifier but only if it's
# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
# We'll format is as trailing comments.
x = f"{x !s
:>0
# comment 21
}"
:>0}"

x = f"{
x!s:>{
0
# comment 21-2
}}"

f"{1
# comment 21-3
:}"

f"{1 # comment 21-4
:} a"


x = f"""
{ # comment 22
Expand All @@ -311,14 +309,14 @@
"""

# Mix of various features.
f"{ # comment 26
f"""{ # comment 26
foo # after foo
:>{
x # after x
}
# comment 27
# comment 28
} woah {x}"
} woah {x}"""


f"""{foo
Expand All @@ -332,8 +330,7 @@
f"{
# comment 31
foo
:>
}"
:>}"

# Assignment statement

Expand Down Expand Up @@ -487,13 +484,11 @@

# This is not a multiline f-string even though it has a newline after the format specifier.
aaaaaaaaaaaaaaaaaa = f"testeeeeeeeeeeeeeeeeeeeeeeeee{
a:.3f
}moreeeeeeeeeeeeeeeeeetest" # comment
a:.3f}moreeeeeeeeeeeeeeeeeetest" # comment

aaaaaaaaaaaaaaaaaa = (
f"testeeeeeeeeeeeeeeeeeeeeeeeee{
a:.3f
}moreeeeeeeeeeeeeeeeeetest" # comment
a:.3f}moreeeeeeeeeeeeeeeeeetest" # comment
)

# The newline is only considered when it's a tripled-quoted f-string.
Expand Down
28 changes: 12 additions & 16 deletions crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/tstring.py
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Expand Up @@ -274,23 +274,21 @@

# Combine conversion flags with format specifiers
x = t"{x = !s
:>0

}"
# This is interesting. There can be a comment after the format specifier but only if it's
# on it's own line. Refer to https://github.com/astral-sh/ruff/pull/7787 for more details.
# We'll format is as trailing comments.
x = t"{x !s
:>0
# comment 21
}"
:>0}"

x = f"{
x!s:>{
0
# comment 21-2
}}"

f"{1
# comment 21-3
:}"

f"{1 # comment 21-4
:} a"

x = t"""
{ # comment 22
x = :.0{y # comment 23
Expand All @@ -306,14 +304,14 @@
"""

# Mix of various features.
t"{ # comment 26
t"""{ # comment 26
foo # after foo
:>{
x # after x
}
# comment 27
# comment 28
} woah {x}"
} woah {x}"""

# Assignment statement

Expand Down Expand Up @@ -467,13 +465,11 @@

# This is not a multiline t-string even though it has a newline after the format specifier.
aaaaaaaaaaaaaaaaaa = t"testeeeeeeeeeeeeeeeeeeeeeeeee{
a:.3f
}moreeeeeeeeeeeeeeeeeetest" # comment
a:.3f}moreeeeeeeeeeeeeeeeeetest" # comment

aaaaaaaaaaaaaaaaaa = (
t"testeeeeeeeeeeeeeeeeeeeeeeeee{
a:.3f
}moreeeeeeeeeeeeeeeeeetest" # comment
a:.3f}moreeeeeeeeeeeeeeeeeetest" # comment
)

# The newline is only considered when it's a tripled-quoted t-string.
Expand Down
33 changes: 12 additions & 21 deletions crates/ruff_python_formatter/src/comments/placement.rs
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Expand Up @@ -323,27 +323,18 @@ fn handle_enclosed_comment<'a>(
AnyNodeRef::TString(tstring) => CommentPlacement::dangling(tstring, comment),
AnyNodeRef::InterpolatedElement(element) => {
if let Some(preceding) = comment.preceding_node() {
if comment.line_position().is_own_line() && element.format_spec.is_some() {
return if comment.following_node().is_some() {
// Own line comment before format specifier
// ```py
// aaaaaaaaaaa = f"""asaaaaaaaaaaaaaaaa {
// aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc + dddddddd
// # comment
// :.3f} cccccccccc"""
// ```
CommentPlacement::trailing(preceding, comment)
} else {
// TODO: This can be removed once format specifiers with a newline are a syntax error.
// This is to handle cases like:
// ```py
// x = f"{x !s
// :>0
// # comment 21
// }"
// ```
CommentPlacement::trailing(element, comment)
};
// Own line comment before format specifier
// ```py
// aaaaaaaaaaa = f"""asaaaaaaaaaaaaaaaa {
// aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc + dddddddd
// # comment
// :.3f} cccccccccc"""
// ```
if comment.line_position().is_own_line()
&& element.format_spec.is_some()
&& comment.following_node().is_some()
{
return CommentPlacement::trailing(preceding, comment);
}
}

Expand Down
40 changes: 4 additions & 36 deletions crates/ruff_python_formatter/src/other/interpolated_string_element.rs
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Expand Up @@ -7,7 +7,7 @@ use ruff_python_ast::{
};
use ruff_text_size::{Ranged, TextSlice};

use crate::comments::{dangling_open_parenthesis_comments, trailing_comments};
use crate::comments::dangling_open_parenthesis_comments;
use crate::context::{
InterpolatedStringState, NodeLevel, WithInterpolatedStringState, WithNodeLevel,
};
Expand Down Expand Up @@ -203,7 +203,7 @@ impl Format<PyFormatContext<'_>> for FormatInterpolatedElement<'_> {
// # comment 27
// :test}"
// ```
if comments.has_trailing_own_line(expression) {
if comments.has_trailing(expression) {
soft_line_break().fmt(f)?;
}

Expand All @@ -214,31 +214,6 @@ impl Format<PyFormatContext<'_>> for FormatInterpolatedElement<'_> {
}
}

// These trailing comments can only occur if the format specifier is
// present. For example,
//
// ```python
// f"{
// x:.3f
// # comment
// }"
// ```

// This can also be triggered outside of a format spec, at
// least until https://github.com/astral-sh/ruff/issues/18632 is a syntax error
// TODO(https://github.com/astral-sh/ruff/issues/18632) Remove this
// and double check if it is still necessary for the triple quoted case
// once this is a syntax error.
// ```py
// f"{
// foo
// :{x}
// # comment 28
// } woah {x}"
// ```
// Any other trailing comments are attached to the expression itself.
trailing_comments(comments.trailing(self.element)).fmt(f)?;

if conversion.is_none() && format_spec.is_none() {
bracket_spacing.fmt(f)?;
}
Expand All @@ -258,15 +233,7 @@ impl Format<PyFormatContext<'_>> for FormatInterpolatedElement<'_> {
let mut f = WithNodeLevel::new(NodeLevel::ParenthesizedExpression, f);

if self.context.is_multiline() {
// TODO: The `or comments.has_trailing...` can be removed once newlines in format specs are a syntax error.
// This is to support the following case:
// ```py
// x = f"{x !s
// :>0
// # comment 21
// }"
// ```
if format_spec.is_none() || comments.has_trailing_own_line(self.element) {
if format_spec.is_none() {
group(&format_args![
open_parenthesis_comments,
soft_block_indent(&item)
Expand All @@ -276,6 +243,7 @@ impl Format<PyFormatContext<'_>> for FormatInterpolatedElement<'_> {
// For strings ending with a format spec, don't add a newline between the end of the format spec
// and closing curly brace because that is invalid syntax for single quoted strings and
// the newline is preserved as part of the format spec for triple quoted strings.

group(&format_args![
open_parenthesis_comments,
indent(&format_args![soft_line_break(), item])
Expand Down
7 changes: 6 additions & 1 deletion crates/ruff_python_formatter/tests/fixtures.rs
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Expand Up @@ -324,7 +324,12 @@ fn format_file(source: &str, options: &PyFormatOptions, input_path: &Path) -> St

(Cow::Owned(without_markers), content)
} else {
let printed = format_module_source(source, options.clone()).expect("Formatting to succeed");
let printed = format_module_source(source, options.clone()).unwrap_or_else(|err| {
panic!(
"Formatting `{input_path} was expected to succeed but it failed: {err}",
input_path = input_path.display()
)
});
let formatted_code = printed.into_code();

ensure_stability_when_formatting_twice(&formatted_code, options, input_path);
Expand Down
3 changes: 1 addition & 2 deletions crates/ruff_python_formatter/tests/snapshots/black_compatibility@cases__pep_701.py.snap
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Expand Up @@ -81,8 +81,7 @@ x = f"a{2+2:=^{foo(x+y**2):something else}one more}b"
f'{(abc:=10)}'

f"This is a really long string, but just make sure that you reflow fstrings {
2+2:d
}"
2+2:d}"
f"This is a really long string, but just make sure that you reflow fstrings correctly {2+2:d}"

f"{2+2=}"
Expand Down
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