Add f-string consistent quotes formatting option

crates/ruff/tests/snapshots/show_settings__display_default_settings.snap

@@ -382,6 +382,7 @@ formatter.line_ending = auto
 formatter.indent_style = space
 formatter.indent_width = 4
 formatter.quote_style = double
+formatter.f_string_consistent_quotes = disabled
 formatter.magic_trailing_comma = respect
 formatter.docstring_code_format = disabled
 formatter.docstring_code_line_width = dynamic

crates/ruff_python_formatter/resources/test/fixtures/ruff/f_string_consistent_quotes.disabled.options.json

@@ -0,0 +1,5 @@
+{
+  "target_version": "py312",
+  "quote_style": "double",
+  "f_string_consistent_quotes": "disabled"
+}

crates/ruff_python_formatter/resources/test/fixtures/ruff/f_string_consistent_quotes.double.options.json

@@ -0,0 +1,5 @@
+{
+  "target_version": "py312",
+  "quote_style": "double",
+  "f_string_consistent_quotes": "enabled"
+}

crates/ruff_python_formatter/resources/test/fixtures/ruff/f_string_consistent_quotes.py

@@ -0,0 +1,38 @@
+# Test consistent quotes in f-strings with PEP 701 (Python 3.12+)
+
+# Basic cases
+basic_double = f"Value: {x}"
+basic_single = f'Value: {x}'
+
+# Nested quotes
+nested_single_in_double = f"He said: '{greeting}'"
+nested_double_in_single = f'She replied: "{response}"'
+
+# Double quotes within expressions
+expr_with_double = f"Value: {f"nested {x}"}"
+expr_with_single = f"Value: {f'nested {x}'}"
+
+# Complex nested expressions
+complex_nested = f"Outer: {f'Middle: {f"Inner: {x}"}'}"
+
+# Quotes that would need to be escaped without PEP 701
+would_need_escape = f"Contains a double quote: {word} says \"{quote}\""
+
+# String with quotes in expression
+quoted_in_expr = f"Result: {get_value(key="test", default="none")}"
+
+# Multiple f-strings in one expression
+multiple = f"First: {x}" + f"Second: {y}"
+
+# Mix of raw and regular f-strings
+raw_mix = rf"Raw: {x}\n" + f"Regular: {y}"
+
+# Multiline f-strings
+multiline = f"""
+Multiple
+lines
+with {value}
+"""
+
+# Complex real-world example
+complex_example = f"User {user['name']} logged in at {format_time(timestamp, fmt="HH:MM:SS")}"

crates/ruff_python_formatter/resources/test/fixtures/ruff/f_string_consistent_quotes.py311.options.json

@@ -0,0 +1,5 @@
+{
+  "target_version": "py311",
+  "quote_style": "double",
+  "f_string_consistent_quotes": "enabled"
+}

crates/ruff_python_formatter/resources/test/fixtures/ruff/f_string_consistent_quotes.single.options.json

@@ -0,0 +1,5 @@
+{
+  "target_version": "py312",
+  "quote_style": "single",
+  "f_string_consistent_quotes": "enabled"
+}

crates/ruff_python_formatter/src/lib.rs

@@ -14,8 +14,8 @@ use crate::comments::{
 };
 pub use crate::context::PyFormatContext;
 pub use crate::options::{
-    DocstringCode, DocstringCodeLineWidth, MagicTrailingComma, PreviewMode, PyFormatOptions,
-    QuoteStyle,
+    DocstringCode, DocstringCodeLineWidth, FStringConsistentQuotes, MagicTrailingComma,
+    PreviewMode, PyFormatOptions, QuoteStyle,
 };
 use crate::range::is_logical_line;
 pub use crate::shared_traits::{AsFormat, FormattedIter, FormattedIterExt, IntoFormat};

crates/ruff_python_formatter/src/options.rs

@@ -62,6 +62,13 @@ pub struct PyFormatOptions {
 
     /// Whether preview style formatting is enabled or not
     preview: PreviewMode,
+
+    /// Controls the quote style for f-strings in Python 3.12+. When enabled,
+    /// f-strings will use consistent quotes (following quote-style) even when nesting quotes,
+    /// leveraging Python 3.12's enhanced string handling capabilities.
+    /// When disabled (default), Ruff will alternate quotes inside f-strings for compatibility with
+    /// older Python versions.
+    f_string_consistent_quotes: FStringConsistentQuotes,
 }
 
 fn default_line_width() -> LineWidth {
@@ -91,6 +98,7 @@ impl Default for PyFormatOptions {
             docstring_code: DocstringCode::default(),
             docstring_code_line_width: DocstringCodeLineWidth::default(),
             preview: PreviewMode::default(),
+            f_string_consistent_quotes: FStringConsistentQuotes::default(),
         }
     }
 }
@@ -144,6 +152,10 @@ impl PyFormatOptions {
         self.preview
     }
 
+    pub const fn f_string_consistent_quotes(&self) -> FStringConsistentQuotes {
+        self.f_string_consistent_quotes
+    }
+
     #[must_use]
     pub fn with_target_version(mut self, target_version: ast::PythonVersion) -> Self {
         self.target_version = target_version;
@@ -204,6 +216,15 @@ impl PyFormatOptions {
         self
     }
 
+    #[must_use]
+    pub fn with_f_string_consistent_quotes(
+        mut self,
+        consistent_quotes: FStringConsistentQuotes,
+    ) -> Self {
+        self.f_string_consistent_quotes = consistent_quotes;
+        self
+    }
+
     #[must_use]
     pub fn with_source_map_generation(mut self, source_map: SourceMapGeneration) -> Self {
         self.source_map_generation = source_map;
@@ -347,6 +368,31 @@ impl fmt::Display for PreviewMode {
     }
 }
 
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Default, CacheKey)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+pub enum FStringConsistentQuotes {
+    #[default]
+    Disabled,
+    Enabled,
+}
+
+impl FStringConsistentQuotes {
+    pub const fn is_enabled(self) -> bool {
+        matches!(self, FStringConsistentQuotes::Enabled)
+    }
+}
+
+impl fmt::Display for FStringConsistentQuotes {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Disabled => write!(f, "disabled"),
+            Self::Enabled => write!(f, "enabled"),
+        }
+    }
+}
+
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Default, CacheKey)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]

crates/ruff_python_formatter/src/string/normalize.rs

@@ -47,16 +47,28 @@ impl<'a, 'src> StringNormalizer<'a, 'src> {
             .unwrap_or(self.context.options().quote_style());
         let supports_pep_701 = self.context.options().target_version().supports_pep_701();
 
-        // For f-strings prefer alternating the quotes unless The outer string is triple quoted and the inner isn't.
+        // For f-strings in Python 3.12+, use consistent quotes if enabled.
+        // Otherwise, alternate quotes for compatibility with older Python versions.
         if let FStringState::InsideExpressionElement(parent_context) = self.context.f_string_state()
         {
             let parent_flags = parent_context.f_string().flags();
+            let consistent_quotes = self
+                .context
+                .options()
+                .f_string_consistent_quotes()
+                .is_enabled();
 
             if !parent_flags.is_triple_quoted() || string.flags().is_triple_quoted() {
+                // When f_string_consistent_quotes is enabled AND we're targeting Python 3.12+,
+                // use the preferred quote style consistently
+                if supports_pep_701 && consistent_quotes && !preferred_quote_style.is_preserve() {
+                    return preferred_quote_style;
+                }
+                // Otherwise, use alternating quotes for compatibility
                 // This logic is even necessary when using preserve and the target python version doesn't support PEP701 because
                 // we might end up joining two f-strings that have different quote styles, in which case we need to alternate the quotes
                 // for inner strings to avoid a syntax error: `string = "this is my string with " f'"{params.get("mine")}"'`
-                if !preferred_quote_style.is_preserve() || !supports_pep_701 {
+                else if !preferred_quote_style.is_preserve() || !supports_pep_701 {
                     return QuoteStyle::from(parent_flags.quote_style().opposite());
                 }
             }

crates/ruff_python_formatter/tests/fixtures.rs

@@ -477,7 +477,8 @@ docstring-code             = {docstring_code:?}
 docstring-code-line-width  = {docstring_code_line_width:?}
 preview                    = {preview:?}
 target_version             = {target_version}
-source_type                = {source_type:?}"#,
+source_type                = {source_type:?}
+f-string-consistent-quotes = {f_string_consistent_quotes:?}"#,
             indent_style = self.0.indent_style(),
             indent_width = self.0.indent_width().value(),
             line_width = self.0.line_width().value(),
@@ -488,7 +489,8 @@ source_type                = {source_type:?}"#,
             docstring_code_line_width = self.0.docstring_code_line_width(),
             preview = self.0.preview(),
             target_version = self.0.target_version(),
-            source_type = self.0.source_type()
+            source_type = self.0.source_type(),
+            f_string_consistent_quotes = self.0.f_string_consistent_quotes()
         )
     }
 }

crates/ruff_python_formatter/tests/snapshots/format@blank_line_before_class_docstring.py.snap

@@ -1,5 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
+assertion_line: 267
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/blank_line_before_class_docstring.py
 ---
 ## Input
@@ -58,6 +59,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Enabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python

crates/ruff_python_formatter/tests/snapshots/format@docstring.py.snap

@@ -1,5 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
+assertion_line: 267
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/docstring.py
 ---
 ## Input
@@ -177,6 +178,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -353,6 +355,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -529,6 +532,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -705,6 +709,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -881,6 +886,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python

crates/ruff_python_formatter/tests/snapshots/format@docstring_code_examples.py.snap

@@ -1,5 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
+assertion_line: 267
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/docstring_code_examples.py
 ---
 ## Input
@@ -1370,6 +1371,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -2742,6 +2744,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -4114,6 +4117,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -5486,6 +5490,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -6858,6 +6863,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -8223,6 +8229,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -9588,6 +9595,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -10962,6 +10970,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -12327,6 +12336,7 @@ docstring-code-line-width  = 60
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python
@@ -13701,6 +13711,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python

crates/ruff_python_formatter/tests/snapshots/format@docstring_code_examples_crlf.py.snap

@@ -1,5 +1,6 @@
 ---
 source: crates/ruff_python_formatter/tests/fixtures.rs
+assertion_line: 267
 input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/docstring_code_examples_crlf.py
 ---
 ## Input
@@ -29,6 +30,7 @@ docstring-code-line-width  = "dynamic"
 preview                    = Disabled
 target_version             = 3.9
 source_type                = Python
+f-string-consistent-quotes = Disabled
 ```
 
 ```python