--show-settings displays active settings in a far more readable format (#9464)

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## Summary

Fixes #8334.

`Display` has been implemented for `ruff_workspace::Settings`, which
gives a much nicer and more readable output to `--show-settings`.

Internally, a `display_settings` utility macro has been implemented to
reduce the boilerplate of the display code.

### Work to be done

- [x] A lot of formatting for `Vec<_>` and `HashSet<_>` types have been
stubbed out, using `Debug` as a fallback. There should be a way to add
generic formatting support for these types as a modifier in
`display_settings`.
- [x] Several complex types were also stubbed out and need proper
`Display` implementations rather than falling back on `Debug`.
- [x] An open question needs to be answered: how important is it that
the output be valid TOML? Some types in settings, such as a hash-map
from a glob pattern to a multi-variant enum, will be hard to rework into
valid _and_ readable TOML.
- [x] Tests need to be implemented.

## Test Plan

Tests consist of a snapshot test for the default `--show-settings`
output and a doctest for `display_settings!`.

crates/ruff_cli/src/commands/show_settings.rs

@@ -35,7 +35,7 @@ pub(crate) fn show_settings(
     if let Some(settings_path) = pyproject_config.path.as_ref() {
         writeln!(writer, "Settings path: {settings_path:?}")?;
     }
-    writeln!(writer, "{settings:#?}")?;
+    write!(writer, "{settings}")?;
 
     Ok(())
 }

crates/ruff_cli/tests/show_settings.rs

@@ -0,0 +1,29 @@
+use insta_cmd::{assert_cmd_snapshot, get_cargo_bin};
+use std::path::Path;
+use std::process::Command;
+
+const BIN_NAME: &str = "ruff";
+
+#[cfg(not(target_os = "windows"))]
+const TEST_FILTERS: &[(&str, &str)] = &[
+    ("\"[^\\*\"]*/pyproject.toml", "\"[BASEPATH]/pyproject.toml"),
+    ("\".*/crates", "\"[BASEPATH]/crates"),
+    ("\".*/\\.ruff_cache", "\"[BASEPATH]/.ruff_cache"),
+    ("\".*/ruff\"", "\"[BASEPATH]\""),
+];
+#[cfg(target_os = "windows")]
+const TEST_FILTERS: &[(&str, &str)] = &[
+    (r#""[^\*"]*\\pyproject.toml"#, "\"[BASEPATH]/pyproject.toml"),
+    (r#"".*\\crates"#, "\"[BASEPATH]/crates"),
+    (r#"".*\\\.ruff_cache"#, "\"[BASEPATH]/.ruff_cache"),
+    (r#"".*\\ruff""#, "\"[BASEPATH]\""),
+    (r#"\\+(\w\w|\s|")"#, "/$1"),
+];
+
+#[test]
+fn display_default_settings() {
+    insta::with_settings!({ filters => TEST_FILTERS.to_vec() }, {
+        assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
+            .args(["check", "--show-settings", "unformatted.py"]).current_dir(Path::new("./resources/test/fixtures")));
+    });
+}

crates/ruff_cli/tests/snapshots/show_settings__display_default_settings.snap

@@ -0,0 +1,368 @@
+---
+source: crates/ruff_cli/tests/show_settings.rs
+info:
+  program: ruff
+  args:
+    - check
+    - "--show-settings"
+    - unformatted.py
+---
+success: true
+exit_code: 0
+----- stdout -----
+Resolved settings for: "[BASEPATH]/crates/ruff_cli/resources/test/fixtures/unformatted.py"
+Settings path: "[BASEPATH]/pyproject.toml"
+
+# General Settings
+cache_dir = "[BASEPATH]/.ruff_cache"
+fix = false
+fix_only = false
+output_format = text
+show_fixes = false
+show_source = false
+unsafe_fixes = hint
+
+# File Resolver Settings
+file_resolver.exclude = [
+	".bzr",
+	".direnv",
+	".eggs",
+	".git",
+	".git-rewrite",
+	".hg",
+	".ipynb_checkpoints",
+	".mypy_cache",
+	".nox",
+	".pants.d",
+	".pyenv",
+	".pytest_cache",
+	".pytype",
+	".ruff_cache",
+	".svn",
+	".tox",
+	".venv",
+	".vscode",
+	"__pypackages__",
+	"_build",
+	"buck-out",
+	"build",
+	"dist",
+	"node_modules",
+	"site-packages",
+	"venv",
+]
+file_resolver.extend_exclude = [
+	"crates/ruff_linter/resources/",
+	"crates/ruff_python_formatter/resources/",
+]
+file_resolver.force_exclude = false
+file_resolver.include = [
+	"*.py",
+	"*.pyi",
+	"**/pyproject.toml",
+]
+file_resolver.extend_include = []
+file_resolver.respect_gitignore = true
+file_resolver.project_root = "[BASEPATH]"
+
+# Linter Settings
+linter.exclude = []
+linter.project_root = "[BASEPATH]"
+linter.rules.enabled = [
+	MultipleImportsOnOneLine,
+	ModuleImportNotAtTopOfFile,
+	MultipleStatementsOnOneLineColon,
+	MultipleStatementsOnOneLineSemicolon,
+	UselessSemicolon,
+	NoneComparison,
+	TrueFalseComparison,
+	NotInTest,
+	NotIsTest,
+	TypeComparison,
+	BareExcept,
+	LambdaAssignment,
+	AmbiguousVariableName,
+	AmbiguousClassName,
+	AmbiguousFunctionName,
+	IOError,
+	SyntaxError,
+	UnusedImport,
+	ImportShadowedByLoopVar,
+	UndefinedLocalWithImportStar,
+	LateFutureImport,
+	UndefinedLocalWithImportStarUsage,
+	UndefinedLocalWithNestedImportStarUsage,
+	FutureFeatureNotDefined,
+	PercentFormatInvalidFormat,
+	PercentFormatExpectedMapping,
+	PercentFormatExpectedSequence,
+	PercentFormatExtraNamedArguments,
+	PercentFormatMissingArgument,
+	PercentFormatMixedPositionalAndNamed,
+	PercentFormatPositionalCountMismatch,
+	PercentFormatStarRequiresSequence,
+	PercentFormatUnsupportedFormatCharacter,
+	StringDotFormatInvalidFormat,
+	StringDotFormatExtraNamedArguments,
+	StringDotFormatExtraPositionalArguments,
+	StringDotFormatMissingArguments,
+	StringDotFormatMixingAutomatic,
+	FStringMissingPlaceholders,
+	MultiValueRepeatedKeyLiteral,
+	MultiValueRepeatedKeyVariable,
+	ExpressionsInStarAssignment,
+	MultipleStarredExpressions,
+	AssertTuple,
+	IsLiteral,
+	InvalidPrintSyntax,
+	IfTuple,
+	BreakOutsideLoop,
+	ContinueOutsideLoop,
+	YieldOutsideFunction,
+	ReturnOutsideFunction,
+	DefaultExceptNotLast,
+	ForwardAnnotationSyntaxError,
+	RedefinedWhileUnused,
+	UndefinedName,
+	UndefinedExport,
+	UndefinedLocal,
+	UnusedVariable,
+	UnusedAnnotation,
+	RaiseNotImplemented,
+]
+linter.rules.should_fix = [
+	MultipleImportsOnOneLine,
+	ModuleImportNotAtTopOfFile,
+	MultipleStatementsOnOneLineColon,
+	MultipleStatementsOnOneLineSemicolon,
+	UselessSemicolon,
+	NoneComparison,
+	TrueFalseComparison,
+	NotInTest,
+	NotIsTest,
+	TypeComparison,
+	BareExcept,
+	LambdaAssignment,
+	AmbiguousVariableName,
+	AmbiguousClassName,
+	AmbiguousFunctionName,
+	IOError,
+	SyntaxError,
+	UnusedImport,
+	ImportShadowedByLoopVar,
+	UndefinedLocalWithImportStar,
+	LateFutureImport,
+	UndefinedLocalWithImportStarUsage,
+	UndefinedLocalWithNestedImportStarUsage,
+	FutureFeatureNotDefined,
+	PercentFormatInvalidFormat,
+	PercentFormatExpectedMapping,
+	PercentFormatExpectedSequence,
+	PercentFormatExtraNamedArguments,
+	PercentFormatMissingArgument,
+	PercentFormatMixedPositionalAndNamed,
+	PercentFormatPositionalCountMismatch,
+	PercentFormatStarRequiresSequence,
+	PercentFormatUnsupportedFormatCharacter,
+	StringDotFormatInvalidFormat,
+	StringDotFormatExtraNamedArguments,
+	StringDotFormatExtraPositionalArguments,
+	StringDotFormatMissingArguments,
+	StringDotFormatMixingAutomatic,
+	FStringMissingPlaceholders,
+	MultiValueRepeatedKeyLiteral,
+	MultiValueRepeatedKeyVariable,
+	ExpressionsInStarAssignment,
+	MultipleStarredExpressions,
+	AssertTuple,
+	IsLiteral,
+	InvalidPrintSyntax,
+	IfTuple,
+	BreakOutsideLoop,
+	ContinueOutsideLoop,
+	YieldOutsideFunction,
+	ReturnOutsideFunction,
+	DefaultExceptNotLast,
+	ForwardAnnotationSyntaxError,
+	RedefinedWhileUnused,
+	UndefinedName,
+	UndefinedExport,
+	UndefinedLocal,
+	UnusedVariable,
+	UnusedAnnotation,
+	RaiseNotImplemented,
+]
+linter.per_file_ignores = {}
+linter.safety_table.forced_safe = []
+linter.safety_table.forced_unsafe = []
+linter.target_version = Py37
+linter.preview = disabled
+linter.explicit_preview_rules = false
+linter.extension.mapping = {}
+linter.allowed_confusables = []
+linter.builtins = []
+linter.dummy_variable_rgx = ^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$
+linter.external = []
+linter.ignore_init_module_imports = false
+linter.logger_objects = []
+linter.namespace_packages = []
+linter.src = ["[BASEPATH]"]
+linter.tab_size = 4
+linter.line_length = 88
+linter.task_tags = [
+	TODO,
+	FIXME,
+	XXX,
+]
+linter.typing_modules = []
+
+# Linter Plugins
+linter.flake8_annotations.mypy_init_return = false
+linter.flake8_annotations.suppress_dummy_args = false
+linter.flake8_annotations.suppress_none_returning = false
+linter.flake8_annotations.allow_star_arg_any = false
+linter.flake8_annotations.ignore_fully_untyped = false
+linter.flake8_bandit.hardcoded_tmp_directory = [
+	/tmp,
+	/var/tmp,
+	/dev/shm,
+]
+linter.flake8_bandit.check_typed_exception = false
+linter.flake8_bugbear.extend_immutable_calls = []
+linter.flake8_builtins.builtins_ignorelist = []
+linter.flake8_comprehensions.allow_dict_calls_with_keyword_arguments = false
+linter.flake8_copyright.notice_rgx = (?i)Copyright\s+(\(C\)\s+)?\d{4}(-\d{4})*
+linter.flake8_copyright.author = none
+linter.flake8_copyright.min_file_size = 0
+linter.flake8_errmsg.max_string_length = 0
+linter.flake8_gettext.functions_names = [
+	_,
+	gettext,
+	ngettext,
+]
+linter.flake8_implicit_str_concat.allow_multiline = true
+linter.flake8_import_conventions.aliases = {"matplotlib": "mpl", "matplotlib.pyplot": "plt", "pandas": "pd", "seaborn": "sns", "tensorflow": "tf", "networkx": "nx", "plotly.express": "px", "polars": "pl", "numpy": "np", "panel": "pn", "pyarrow": "pa", "altair": "alt", "tkinter": "tk", "holoviews": "hv"}
+linter.flake8_import_conventions.banned_aliases = {}
+linter.flake8_import_conventions.banned_from = []
+linter.flake8_pytest_style.fixture_parentheses = true
+linter.flake8_pytest_style.parametrize_names_type = tuple
+linter.flake8_pytest_style.parametrize_values_type = list
+linter.flake8_pytest_style.parametrize_values_row_type = tuple
+linter.flake8_pytest_style.raises_require_match_for = [
+	BaseException,
+	Exception,
+	ValueError,
+	OSError,
+	IOError,
+	EnvironmentError,
+	socket.error,
+]
+linter.flake8_pytest_style.raises_extend_require_match_for = []
+linter.flake8_pytest_style.mark_parentheses = true
+linter.flake8_quotes.inline_quotes = double
+linter.flake8_quotes.multiline_quotes = double
+linter.flake8_quotes.docstring_quotes = double
+linter.flake8_quotes.avoid_escape = true
+linter.flake8_self.ignore_names = [
+	_make,
+	_asdict,
+	_replace,
+	_fields,
+	_field_defaults,
+	_name_,
+	_value_,
+]
+linter.flake8_tidy_imports.ban_relative_imports = "parents"
+linter.flake8_tidy_imports.banned_api = {}
+linter.flake8_tidy_imports.banned_module_level_imports = []
+linter.flake8_type_checking.strict = false
+linter.flake8_type_checking.exempt_modules = [
+	typing,
+	typing_extensions,
+]
+linter.flake8_type_checking.runtime_required_base_classes = []
+linter.flake8_type_checking.runtime_required_decorators = []
+linter.flake8_type_checking.quote_annotations = false
+linter.flake8_unused_arguments.ignore_variadic_names = false
+linter.isort.required_imports = []
+linter.isort.combine_as_imports = false
+linter.isort.force_single_line = false
+linter.isort.force_sort_within_sections = false
+linter.isort.detect_same_package = true
+linter.isort.case_sensitive = false
+linter.isort.force_wrap_aliases = false
+linter.isort.force_to_top = []
+linter.isort.known_modules = {}
+linter.isort.order_by_type = true
+linter.isort.relative_imports_order = furthest_to_closest
+linter.isort.single_line_exclusions = []
+linter.isort.split_on_trailing_comma = true
+linter.isort.classes = []
+linter.isort.constants = []
+linter.isort.variables = []
+linter.isort.no_lines_before = []
+linter.isort.lines_after_imports = -1
+linter.isort.lines_between_types = 0
+linter.isort.forced_separate = []
+linter.isort.section_order = [
+	known { type = future },
+	known { type = standard_library },
+	known { type = third_party },
+	known { type = first_party },
+	known { type = local_folder },
+]
+linter.isort.no_sections = false
+linter.isort.from_first = false
+linter.isort.length_sort = false
+linter.isort.length_sort_straight = false
+linter.mccabe.max_complexity = 10
+linter.pep8_naming.ignore_names = [
+	setUp,
+	tearDown,
+	setUpClass,
+	tearDownClass,
+	setUpModule,
+	tearDownModule,
+	asyncSetUp,
+	asyncTearDown,
+	setUpTestData,
+	failureException,
+	longMessage,
+	maxDiff,
+]
+linter.pep8_naming.classmethod_decorators = []
+linter.pep8_naming.staticmethod_decorators = []
+linter.pycodestyle.max_line_length = 88
+linter.pycodestyle.max_doc_length = none
+linter.pycodestyle.ignore_overlong_task_comments = false
+linter.pyflakes.extend_generics = []
+linter.pylint.allow_magic_value_types = [
+	str,
+	bytes,
+]
+linter.pylint.allow_dunder_method_names = []
+linter.pylint.max_args = 5
+linter.pylint.max_positional_args = 5
+linter.pylint.max_returns = 6
+linter.pylint.max_bool_expr = 5
+linter.pylint.max_branches = 12
+linter.pylint.max_statements = 50
+linter.pylint.max_public_methods = 20
+linter.pylint.max_locals = 15
+linter.pyupgrade.keep_runtime_typing = false
+
+# Formatter Settings
+formatter.exclude = []
+formatter.target_version = Py37
+formatter.preview = disabled
+formatter.line_width = 88
+formatter.line_ending = auto
+formatter.indent_style = space
+formatter.indent_width = 4
+formatter.quote_style = double
+formatter.magic_trailing_comma = respect
+formatter.docstring_code_format = disabled
+formatter.docstring_code_line_width = dynamic
+
+----- stderr -----
+

crates/ruff_formatter/src/lib.rs

@@ -35,6 +35,7 @@ mod source_code;
 use crate::formatter::Formatter;
 use crate::group_id::UniqueGroupIdBuilder;
 use crate::prelude::TagKind;
+use std::fmt;
 use std::fmt::{Debug, Display};
 use std::marker::PhantomData;
 use std::num::{NonZeroU16, NonZeroU8, TryFromIntError};
@@ -113,6 +114,12 @@ impl Default for IndentWidth {
     }
 }
 
+impl Display for IndentWidth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        Display::fmt(&self.0, f)
+    }
+}
+
 impl TryFrom<u8> for IndentWidth {
     type Error = TryFromIntError;
 
@@ -146,6 +153,12 @@ impl Default for LineWidth {
     }
 }
 
+impl Display for LineWidth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        Display::fmt(&self.0, f)
+    }
+}
+
 impl TryFrom<u16> for LineWidth {
     type Error = TryFromIntError;
 

crates/ruff_linter/src/line_width.rs

@@ -1,4 +1,5 @@
 use std::error::Error;
+use std::fmt;
 use std::hash::Hasher;
 use std::num::{NonZeroU16, NonZeroU8, ParseIntError};
 use std::str::FromStr;
@@ -39,6 +40,12 @@ impl Default for LineLength {
     }
 }
 
+impl fmt::Display for LineLength {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
 impl CacheKey for LineLength {
     fn cache_key(&self, state: &mut CacheKeyHasher) {
         state.write_u16(self.0.get());
@@ -248,6 +255,12 @@ impl Default for IndentWidth {
     }
 }
 
+impl fmt::Display for IndentWidth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Display::fmt(&self.0, f)
+    }
+}
+
 impl From<NonZeroU8> for IndentWidth {
     fn from(tab_size: NonZeroU8) -> Self {
         Self(tab_size)

crates/ruff_linter/src/registry/rule_set.rs

@@ -1,6 +1,6 @@
 use crate::registry::Rule;
 use ruff_macros::CacheKey;
-use std::fmt::{Debug, Formatter};
+use std::fmt::{Debug, Display, Formatter};
 use std::iter::FusedIterator;
 
 const RULESET_SIZE: usize = 13;
@@ -269,6 +269,21 @@ impl Debug for RuleSet {
     }
 }
 
+impl Display for RuleSet {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        if self.is_empty() {
+            write!(f, "[]")?;
+        } else {
+            writeln!(f, "[")?;
+            for rule in self {
+                writeln!(f, "\t{rule:?},")?;
+            }
+            write!(f, "]")?;
+        }
+        Ok(())
+    }
+}
+
 impl FromIterator<Rule> for RuleSet {
     fn from_iter<T: IntoIterator<Item = Rule>>(iter: T) -> Self {
         let mut set = RuleSet::empty();

crates/ruff_linter/src/rules/flake8_annotations/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `flake-annotations` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 #[allow(clippy::struct_excessive_bools)]
@@ -11,3 +13,20 @@ pub struct Settings {
     pub allow_star_arg_any: bool,
     pub ignore_fully_untyped: bool,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_annotations",
+            fields = [
+                self.mypy_init_return,
+                self.suppress_dummy_args,
+                self.suppress_none_returning,
+                self.allow_star_arg_any,
+                self.ignore_fully_untyped
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_bandit/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `flake8-bandit` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 pub fn default_tmp_dirs() -> Vec<String> {
     ["/tmp", "/var/tmp", "/dev/shm"]
@@ -22,3 +24,17 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_bandit",
+            fields = [
+                self.hardcoded_tmp_directory | array,
+                self.check_typed_exception
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_bugbear/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `flake8-bugbear` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub extend_immutable_calls: Vec<String>,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_bugbear",
+            fields = [
+                self.extend_immutable_calls | array
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_builtins/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `flake8-builtins` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub builtins_ignorelist: Vec<String>,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_builtins",
+            fields = [
+                self.builtins_ignorelist | array
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_comprehensions/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `flake8-comprehensions` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub allow_dict_calls_with_keyword_arguments: bool,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_comprehensions",
+            fields = [
+                self.allow_dict_calls_with_keyword_arguments
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_copyright/settings.rs

@@ -2,7 +2,9 @@
 
 use once_cell::sync::Lazy;
 use regex::Regex;
+use std::fmt::{Display, Formatter};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 #[derive(Debug, CacheKey)]
@@ -24,3 +26,18 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_copyright",
+            fields = [
+                self.notice_rgx,
+                self.author | optional,
+                self.min_file_size,
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_errmsg/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `flake8-errmsg` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub max_string_length: usize,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_errmsg",
+            fields = [
+                self.max_string_length
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_gettext/settings.rs

@@ -1,4 +1,6 @@
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, CacheKey)]
 pub struct Settings {
@@ -20,3 +22,16 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_gettext",
+            fields = [
+                self.functions_names | array
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_implicit_str_concat/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `flake8-implicit-str-concat` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, CacheKey)]
 pub struct Settings {
@@ -14,3 +16,16 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_implicit_str_concat",
+            fields = [
+                self.allow_multiline
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_import_conventions/settings.rs

@@ -1,7 +1,9 @@
 //! Settings for import conventions.
 
 use rustc_hash::{FxHashMap, FxHashSet};
+use std::fmt::{Display, Formatter};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 const CONVENTIONAL_ALIASES: &[(&str, &str)] = &[
@@ -44,3 +46,18 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_import_conventions",
+            fields = [
+                self.aliases | debug,
+                self.banned_aliases | debug,
+                self.banned_from | array,
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_pytest_style/settings.rs

@@ -1,7 +1,9 @@
 //! Settings for the `flake8-pytest-style` plugin.
 use std::error::Error;
 use std::fmt;
+use std::fmt::Formatter;
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 use crate::settings::types::IdentifierPattern;
@@ -47,6 +49,25 @@ impl Default for Settings {
     }
 }
 
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_pytest_style",
+            fields = [
+                self.fixture_parentheses,
+                self.parametrize_names_type,
+                self.parametrize_values_type,
+                self.parametrize_values_row_type,
+                self.raises_require_match_for | array,
+                self.raises_extend_require_match_for | array,
+                self.mark_parentheses
+            ]
+        }
+        Ok(())
+    }
+}
+
 /// Error returned by the [`TryFrom`] implementation of [`Settings`].
 #[derive(Debug)]
 pub enum SettingsError {

crates/ruff_linter/src/rules/flake8_quotes/settings.rs

@@ -1,7 +1,9 @@
 //! Settings for the `flake8-quotes` plugin.
 
 use serde::{Deserialize, Serialize};
+use std::fmt::{Display, Formatter};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize, CacheKey)]
@@ -39,6 +41,22 @@ impl Default for Settings {
     }
 }
 
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_quotes",
+            fields = [
+                self.inline_quotes,
+                self.multiline_quotes,
+                self.docstring_quotes,
+                self.avoid_escape
+            ]
+        }
+        Ok(())
+    }
+}
+
 impl Quote {
     #[must_use]
     pub const fn opposite(self) -> Self {
@@ -56,3 +74,12 @@ impl Quote {
         }
     }
 }
+
+impl Display for Quote {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Double => write!(f, "double"),
+            Self::Single => write!(f, "single"),
+        }
+    }
+}

crates/ruff_linter/src/rules/flake8_self/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `flake8-self` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 // By default, ignore the `namedtuple` methods and attributes, as well as the
 // _sunder_ names in Enum, which are underscore-prefixed to prevent conflicts
@@ -27,3 +29,16 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_self",
+            fields = [
+                self.ignore_names | array
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_tidy_imports/settings.rs

@@ -1,6 +1,8 @@
 use rustc_hash::FxHashMap;
 use serde::{Deserialize, Serialize};
+use std::fmt::{Display, Formatter};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, CacheKey)]
@@ -22,9 +24,33 @@ pub enum Strictness {
     All,
 }
 
+impl Display for Strictness {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Parents => write!(f, "\"parents\""),
+            Self::All => write!(f, "\"all\""),
+        }
+    }
+}
+
 #[derive(Debug, CacheKey, Default)]
 pub struct Settings {
     pub ban_relative_imports: Strictness,
     pub banned_api: FxHashMap<String, ApiBan>,
     pub banned_module_level_imports: Vec<String>,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_tidy_imports",
+            fields = [
+                self.ban_relative_imports,
+                self.banned_api | debug,
+                self.banned_module_level_imports | array,
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_type_checking/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `flake8-type-checking` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, CacheKey)]
 pub struct Settings {
@@ -22,3 +24,20 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_type_checking",
+            fields = [
+                self.strict,
+                self.exempt_modules | array,
+                self.runtime_required_base_classes | array,
+                self.runtime_required_decorators | array,
+                self.quote_annotations
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/flake8_unused_arguments/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `flake8-unused-arguments` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub ignore_variadic_names: bool,
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.flake8_unused_arguments",
+            fields = [
+                self.ignore_variadic_names
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/isort/categorize.rs

@@ -1,4 +1,5 @@
 use std::collections::BTreeMap;
+use std::fmt;
 use std::hash::BuildHasherDefault;
 use std::path::{Path, PathBuf};
 use std::{fs, iter};
@@ -40,6 +41,18 @@ pub enum ImportType {
     LocalFolder,
 }
 
+impl fmt::Display for ImportType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Future => write!(f, "future"),
+            Self::StandardLibrary => write!(f, "standard_library"),
+            Self::ThirdParty => write!(f, "third_party"),
+            Self::FirstParty => write!(f, "first_party"),
+            Self::LocalFolder => write!(f, "local_folder"),
+        }
+    }
+}
+
 #[derive(Debug, PartialOrd, Ord, PartialEq, Eq, Clone, Hash, Serialize, Deserialize, CacheKey)]
 #[serde(untagged)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
@@ -48,6 +61,15 @@ pub enum ImportSection {
     UserDefined(String),
 }
 
+impl fmt::Display for ImportSection {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Known(import_type) => write!(f, "known {{ type = {import_type} }}",),
+            Self::UserDefined(string) => fmt::Debug::fmt(string, f),
+        }
+    }
+}
+
 #[derive(Debug)]
 enum Reason<'a> {
     NonZeroLevel,
@@ -378,3 +400,18 @@ impl KnownModules {
         user_defined
     }
 }
+
+impl fmt::Display for KnownModules {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.known.is_empty() {
+            write!(f, "{{}}")?;
+        } else {
+            writeln!(f, "{{")?;
+            for (pattern, import_section) in &self.known {
+                writeln!(f, "\t{pattern} => {import_section:?},")?;
+            }
+            write!(f, "}}")?;
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/isort/settings.rs

@@ -3,10 +3,12 @@
 use std::collections::BTreeSet;
 use std::error::Error;
 use std::fmt;
+use std::fmt::{Display, Formatter};
 
 use serde::{Deserialize, Serialize};
 use strum::IntoEnumIterator;
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 use crate::rules::isort::categorize::KnownModules;
@@ -32,6 +34,15 @@ impl Default for RelativeImportsOrder {
     }
 }
 
+impl Display for RelativeImportsOrder {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::ClosestToFurthest => write!(f, "closest_to_furthest"),
+            Self::FurthestToClosest => write!(f, "furthest_to_closest"),
+        }
+    }
+}
+
 #[derive(Debug, CacheKey)]
 #[allow(clippy::struct_excessive_bools)]
 pub struct Settings {
@@ -94,6 +105,43 @@ impl Default for Settings {
     }
 }
 
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.isort",
+            fields = [
+                self.required_imports | array,
+                self.combine_as_imports,
+                self.force_single_line,
+                self.force_sort_within_sections,
+                self.detect_same_package,
+                self.case_sensitive,
+                self.force_wrap_aliases,
+                self.force_to_top | array,
+                self.known_modules,
+                self.order_by_type,
+                self.relative_imports_order,
+                self.single_line_exclusions | array,
+                self.split_on_trailing_comma,
+                self.classes | array,
+                self.constants | array,
+                self.variables | array,
+                self.no_lines_before | array,
+                self.lines_after_imports,
+                self.lines_between_types,
+                self.forced_separate | array,
+                self.section_order | array,
+                self.no_sections,
+                self.from_first,
+                self.length_sort,
+                self.length_sort_straight
+            ]
+        }
+        Ok(())
+    }
+}
+
 /// Error returned by the [`TryFrom`] implementation of [`Settings`].
 #[derive(Debug)]
 pub enum SettingsError {

crates/ruff_linter/src/rules/mccabe/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `mccabe` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt::{Display, Formatter};
 
 #[derive(Debug, CacheKey)]
 pub struct Settings {
@@ -16,3 +18,16 @@ impl Default for Settings {
         }
     }
 }
+
+impl Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.mccabe",
+            fields = [
+                self.max_complexity
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/pep8_naming/settings.rs

@@ -2,7 +2,9 @@
 
 use std::error::Error;
 use std::fmt;
+use std::fmt::Formatter;
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 use crate::settings::types::IdentifierPattern;
@@ -44,6 +46,21 @@ impl Default for Settings {
     }
 }
 
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pep8_naming",
+            fields = [
+                self.ignore_names | array,
+                self.classmethod_decorators | array,
+                self.staticmethod_decorators | array
+            ]
+        }
+        Ok(())
+    }
+}
+
 /// Error returned by the [`TryFrom`] implementation of [`Settings`].
 #[derive(Debug)]
 pub enum SettingsError {

crates/ruff_linter/src/rules/pycodestyle/settings.rs

@@ -1,6 +1,8 @@
 //! Settings for the `pycodestyle` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt;
 
 use crate::line_width::LineLength;
 
@@ -10,3 +12,18 @@ pub struct Settings {
     pub max_doc_length: Option<LineLength>,
     pub ignore_overlong_task_comments: bool,
 }
+
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pycodestyle",
+            fields = [
+                self.max_line_length,
+                self.max_doc_length | optional,
+                self.ignore_overlong_task_comments,
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/pydocstyle/settings.rs

@@ -1,9 +1,11 @@
 //! Settings for the `pydocstyle` plugin.
 
 use std::collections::BTreeSet;
+use std::fmt;
 
 use serde::{Deserialize, Serialize};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 use crate::registry::Rule;
@@ -71,9 +73,34 @@ impl Convention {
     }
 }
 
+impl fmt::Display for Convention {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Google => write!(f, "google"),
+            Self::Numpy => write!(f, "numpy"),
+            Self::Pep257 => write!(f, "pep257"),
+        }
+    }
+}
+
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub convention: Option<Convention>,
     pub ignore_decorators: BTreeSet<String>,
     pub property_decorators: BTreeSet<String>,
 }
+
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pydocstyle",
+            fields = [
+                self.convention | optional,
+                self.ignore_decorators | debug,
+                self.property_decorators | debug
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/pyflakes/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `Pyflakes` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt;
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub extend_generics: Vec<String>,
 }
+
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pyflakes",
+            fields = [
+                self.extend_generics | debug
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/pylint/settings.rs

@@ -2,7 +2,9 @@
 
 use rustc_hash::FxHashSet;
 use serde::{Deserialize, Serialize};
+use std::fmt;
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 use ruff_python_ast::{ExprNumberLiteral, LiteralExpressionRef, Number};
 
@@ -34,6 +36,18 @@ impl ConstantType {
     }
 }
 
+impl fmt::Display for ConstantType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Bytes => write!(f, "bytes"),
+            Self::Complex => write!(f, "complex"),
+            Self::Float => write!(f, "float"),
+            Self::Int => write!(f, "int"),
+            Self::Str => write!(f, "str"),
+        }
+    }
+}
+
 #[derive(Debug, CacheKey)]
 pub struct Settings {
     pub allow_magic_value_types: Vec<ConstantType>,
@@ -64,3 +78,25 @@ impl Default for Settings {
         }
     }
 }
+
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pylint",
+            fields = [
+                self.allow_magic_value_types | array,
+                self.allow_dunder_method_names | array,
+                self.max_args,
+                self.max_positional_args,
+                self.max_returns,
+                self.max_bool_expr,
+                self.max_branches,
+                self.max_statements,
+                self.max_public_methods,
+                self.max_locals
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/pyupgrade/settings.rs

@@ -1,8 +1,23 @@
 //! Settings for the `pyupgrade` plugin.
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
+use std::fmt;
 
 #[derive(Debug, Default, CacheKey)]
 pub struct Settings {
     pub keep_runtime_typing: bool,
 }
+
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.pyupgrade",
+            fields = [
+                self.keep_runtime_typing
+            ]
+        }
+        Ok(())
+    }
+}

crates/ruff_linter/src/rules/ruff/mod.rs

@@ -16,8 +16,7 @@ mod tests {
 
     use crate::pyproject_toml::lint_pyproject_toml;
     use crate::registry::Rule;
-    use crate::settings::resolve_per_file_ignores;
+    use crate::settings::types::{PerFileIgnore, PerFileIgnores, PreviewMode, PythonVersion};
-    use crate::settings::types::{PerFileIgnore, PreviewMode, PythonVersion};
     use crate::test::{test_path, test_resource_path};
     use crate::{assert_messages, settings};
 
@@ -171,7 +170,7 @@ mod tests {
         let mut settings =
             settings::LinterSettings::for_rules(vec![Rule::UnusedNOQA, Rule::UnusedImport]);
 
-        settings.per_file_ignores = resolve_per_file_ignores(vec![PerFileIgnore::new(
+        settings.per_file_ignores = PerFileIgnores::resolve(vec![PerFileIgnore::new(
             "RUF100_2.py".to_string(),
             &["F401".parse().unwrap()],
             None,
@@ -228,7 +227,7 @@ mod tests {
         let diagnostics = test_path(
             Path::new("ruff/ruff_per_file_ignores.py"),
             &settings::LinterSettings {
-                per_file_ignores: resolve_per_file_ignores(vec![PerFileIgnore::new(
+                per_file_ignores: PerFileIgnores::resolve(vec![PerFileIgnore::new(
                     "ruff_per_file_ignores.py".to_string(),
                     &["F401".parse().unwrap(), "RUF100".parse().unwrap()],
                     None,

crates/ruff_linter/src/settings/fix_safety_table.rs

@@ -1,4 +1,4 @@
-use std::fmt::Debug;
+use std::fmt::{Debug, Display, Formatter};
 
 use ruff_diagnostics::Applicability;
 use ruff_macros::CacheKey;
@@ -6,6 +6,7 @@ use rustc_hash::FxHashMap;
 use strum::IntoEnumIterator;
 
 use crate::{
+    display_settings,
     registry::{Rule, RuleSet},
     rule_selector::{PreviewOptions, Specificity},
     RuleSelector,
@@ -95,6 +96,20 @@ impl FixSafetyTable {
     }
 }
 
+impl Display for FixSafetyTable {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.safety_table",
+            fields = [
+                self.forced_safe,
+                self.forced_unsafe
+            ]
+        }
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/ruff_linter/src/settings/mod.rs

@@ -2,10 +2,9 @@
 //! command-line options. Structure is optimized for internal usage, as opposed
 //! to external visibility or parsing.
 
+use std::fmt::{Display, Formatter};
 use std::path::{Path, PathBuf};
 
-use anyhow::Result;
-use globset::{Glob, GlobMatcher};
 use once_cell::sync::Lazy;
 use path_absolutize::path_dedot;
 use regex::Regex;
@@ -15,7 +14,7 @@ use crate::codes::RuleCodePrefix;
 use ruff_macros::CacheKey;
 
 use crate::line_width::LineLength;
-use crate::registry::{Linter, Rule, RuleSet};
+use crate::registry::{Linter, Rule};
 use crate::rules::{
     flake8_annotations, flake8_bandit, flake8_bugbear, flake8_builtins, flake8_comprehensions,
     flake8_copyright, flake8_errmsg, flake8_gettext, flake8_implicit_str_concat,
@@ -23,7 +22,7 @@ use crate::rules::{
     flake8_tidy_imports, flake8_type_checking, flake8_unused_arguments, isort, mccabe, pep8_naming,
     pycodestyle, pydocstyle, pyflakes, pylint, pyupgrade,
 };
-use crate::settings::types::{ExtensionMapping, FilePatternSet, PerFileIgnore, PythonVersion};
+use crate::settings::types::{ExtensionMapping, FilePatternSet, PerFileIgnores, PythonVersion};
 use crate::{codes, RuleSelector};
 
 use super::line_width::IndentWidth;
@@ -38,6 +37,126 @@ pub mod flags;
 pub mod rule_table;
 pub mod types;
 
+/// `display_settings!` is a macro that can display and format struct fields in a readable,
+/// namespaced format. It's particularly useful at generating `Display` implementations
+/// for types used in settings.
+///
+/// # Example
+/// ```
+/// use std::fmt;
+/// use ruff_linter::display_settings;
+/// #[derive(Default)]
+/// struct Settings {
+///     option_a: bool,
+///     sub_settings: SubSettings,
+///     option_b: String,
+/// }
+///
+/// struct SubSettings {
+///     name: String
+/// }
+///
+/// impl Default for SubSettings {
+///     fn default() -> Self {
+///         Self { name: "Default Name".into() }
+///     }
+///
+/// }
+///
+/// impl fmt::Display for SubSettings {
+///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+///         display_settings! {
+///             formatter = f,
+///             namespace = "sub_settings",
+///             fields = [
+///                 self.name | quoted
+///             ]
+///         }
+///         Ok(())
+///     }
+///
+/// }
+///
+/// impl fmt::Display for Settings {
+///     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+///         display_settings! {
+///             formatter = f,
+///             fields = [
+///                 self.option_a,
+///                 self.sub_settings | nested,
+///                 self.option_b | quoted,
+///             ]
+///         }
+///         Ok(())
+///     }
+///
+/// }
+///
+/// const EXPECTED_OUTPUT: &str = r#"option_a = false
+/// sub_settings.name = "Default Name"
+/// option_b = ""
+/// "#;
+///
+/// fn main() {
+///     let settings = Settings::default();
+///     assert_eq!(format!("{settings}"), EXPECTED_OUTPUT);
+/// }
+/// ```
+#[macro_export]
+macro_rules! display_settings {
+    (formatter = $fmt:ident, namespace = $namespace:literal, fields = [$($settings:ident.$field:ident $(| $modifier:tt)?),* $(,)?]) => {
+        {
+            const _PREFIX: &str = concat!($namespace, ".");
+            $(
+                display_settings!(@field $fmt, _PREFIX, $settings.$field $(| $modifier)?);
+            )*
+        }
+    };
+    (formatter = $fmt:ident, fields = [$($settings:ident.$field:ident $(| $modifier:tt)?),* $(,)?]) => {
+        {
+            const _PREFIX: &str = "";
+            $(
+                display_settings!(@field $fmt, _PREFIX, $settings.$field $(| $modifier)?);
+            )*
+        }
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident | debug) => {
+        writeln!($fmt, "{}{} = {:?}", $prefix, stringify!($field), $settings.$field)?;
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident | quoted) => {
+        writeln!($fmt, "{}{} = \"{}\"", $prefix, stringify!($field), $settings.$field)?;
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident | nested) => {
+        write!($fmt, "{}", $settings.$field)?;
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident | optional) => {
+        {
+            write!($fmt, "{}{} = ", $prefix, stringify!($field))?;
+            match &$settings.$field {
+                Some(value) => writeln!($fmt, "{}", value)?,
+                None        => writeln!($fmt, "none")?
+            };
+        }
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident | array) => {
+        {
+            write!($fmt, "{}{} = ", $prefix, stringify!($field))?;
+            if $settings.$field.is_empty() {
+                writeln!($fmt, "[]")?;
+            } else {
+                writeln!($fmt, "[")?;
+                for elem in &$settings.$field {
+                    writeln!($fmt, "\t{elem},")?;
+                }
+                writeln!($fmt, "]")?;
+            }
+        }
+    };
+    (@field $fmt:ident, $prefix:ident, $settings:ident.$field:ident) => {
+        writeln!($fmt, "{}{} = {}", $prefix, stringify!($field), $settings.$field)?;
+    };
+}
+
 #[derive(Debug, CacheKey)]
 pub struct LinterSettings {
     pub exclude: FilePatternSet,
@@ -45,7 +164,7 @@ pub struct LinterSettings {
     pub project_root: PathBuf,
 
     pub rules: RuleTable,
-    pub per_file_ignores: Vec<(GlobMatcher, GlobMatcher, RuleSet)>,
+    pub per_file_ignores: PerFileIgnores,
     pub fix_safety: FixSafetyTable,
 
     pub target_version: PythonVersion,
@@ -93,6 +212,73 @@ pub struct LinterSettings {
     pub pyupgrade: pyupgrade::settings::Settings,
 }
 
+impl Display for LinterSettings {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        writeln!(f, "\n# Linter Settings")?;
+        display_settings! {
+            formatter = f,
+            namespace = "linter",
+            fields = [
+                self.exclude,
+                self.project_root | debug,
+
+                self.rules | nested,
+                self.per_file_ignores,
+                self.fix_safety | nested,
+
+                self.target_version | debug,
+                self.preview,
+                self.explicit_preview_rules,
+                self.extension | nested,
+
+                self.allowed_confusables | array,
+                self.builtins | array,
+                self.dummy_variable_rgx,
+                self.external | array,
+                self.ignore_init_module_imports,
+                self.logger_objects | array,
+                self.namespace_packages | debug,
+                self.src | debug,
+                self.tab_size,
+                self.line_length,
+                self.task_tags | array,
+                self.typing_modules | array,
+            ]
+        }
+        writeln!(f, "\n# Linter Plugins")?;
+        display_settings! {
+            formatter = f,
+            namespace = "linter",
+            fields = [
+                self.flake8_annotations | nested,
+                self.flake8_bandit | nested,
+                self.flake8_bugbear | nested,
+                self.flake8_builtins | nested,
+                self.flake8_comprehensions | nested,
+                self.flake8_copyright | nested,
+                self.flake8_errmsg | nested,
+                self.flake8_gettext | nested,
+                self.flake8_implicit_str_concat | nested,
+                self.flake8_import_conventions | nested,
+                self.flake8_pytest_style | nested,
+                self.flake8_quotes | nested,
+                self.flake8_self | nested,
+                self.flake8_tidy_imports | nested,
+                self.flake8_type_checking | nested,
+                self.flake8_unused_arguments | nested,
+                self.isort | nested,
+                self.mccabe | nested,
+                self.pep8_naming | nested,
+                self.pycodestyle | nested,
+                self.pyflakes | nested,
+                self.pylint | nested,
+                self.pyupgrade | nested,
+            ]
+        }
+        Ok(())
+    }
+}
+
 pub const DEFAULT_SELECTORS: &[RuleSelector] = &[
     RuleSelector::Linter(Linter::Pyflakes),
     // Only include pycodestyle rules that do not overlap with the formatter
@@ -152,7 +338,7 @@ impl LinterSettings {
             logger_objects: vec![],
             namespace_packages: vec![],
 
-            per_file_ignores: vec![],
+            per_file_ignores: PerFileIgnores::default(),
             fix_safety: FixSafetyTable::default(),
 
             src: vec![path_dedot::CWD.clone()],
@@ -204,22 +390,3 @@ impl Default for LinterSettings {
         Self::new(path_dedot::CWD.as_path())
     }
 }
-
-/// Given a list of patterns, create a `GlobSet`.
-pub fn resolve_per_file_ignores(
-    per_file_ignores: Vec<PerFileIgnore>,
-) -> Result<Vec<(GlobMatcher, GlobMatcher, RuleSet)>> {
-    per_file_ignores
-        .into_iter()
-        .map(|per_file_ignore| {
-            // Construct absolute path matcher.
-            let absolute =
-                Glob::new(&per_file_ignore.absolute.to_string_lossy())?.compile_matcher();
-
-            // Construct basename matcher.
-            let basename = Glob::new(&per_file_ignore.basename)?.compile_matcher();
-
-            Ok((absolute, basename, per_file_ignore.rules))
-        })
-        .collect()
-}

crates/ruff_linter/src/settings/rule_table.rs

@@ -1,5 +1,6 @@
-use std::fmt::Debug;
+use std::fmt::{Debug, Display, Formatter};
 
+use crate::display_settings;
 use ruff_macros::CacheKey;
 
 use crate::registry::{Rule, RuleSet, RuleSetIterator};
@@ -62,6 +63,20 @@ impl RuleTable {
     }
 }
 
+impl Display for RuleTable {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.rules",
+            fields = [
+                self.enabled,
+                self.should_fix
+            ]
+        }
+        Ok(())
+    }
+}
+
 impl FromIterator<Rule> for RuleTable {
     fn from_iter<T: IntoIterator<Item = Rule>>(iter: T) -> Self {
         let rules = RuleSet::from_iter(iter);

crates/ruff_linter/src/settings/types.rs

@@ -1,3 +1,4 @@
+use std::fmt::{Display, Formatter};
 use std::hash::{Hash, Hasher};
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
@@ -5,7 +6,7 @@ use std::str::FromStr;
 use std::string::ToString;
 
 use anyhow::{bail, Result};
-use globset::{Glob, GlobSet, GlobSetBuilder};
+use globset::{Glob, GlobMatcher, GlobSet, GlobSetBuilder};
 use pep440_rs::{Version as Pep440Version, VersionSpecifiers};
 use rustc_hash::FxHashMap;
 use serde::{de, Deserialize, Deserializer, Serialize};
@@ -17,9 +18,9 @@ use ruff_diagnostics::Applicability;
 use ruff_macros::CacheKey;
 use ruff_python_ast::PySourceType;
 
-use crate::fs;
 use crate::registry::RuleSet;
 use crate::rule_selector::RuleSelector;
+use crate::{display_settings, fs};
 
 #[derive(
     Clone,
@@ -121,6 +122,15 @@ impl From<bool> for PreviewMode {
     }
 }
 
+impl Display for PreviewMode {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Disabled => write!(f, "disabled"),
+            Self::Enabled => write!(f, "enabled"),
+        }
+    }
+}
+
 /// Toggle for unsafe fixes.
 /// `Hint` will not apply unsafe fixes but a message will be shown when they are available.
 /// `Disabled` will not apply unsafe fixes or show a message.
@@ -133,6 +143,20 @@ pub enum UnsafeFixes {
     Enabled,
 }
 
+impl Display for UnsafeFixes {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                Self::Hint => "hint",
+                Self::Disabled => "disabled",
+                Self::Enabled => "enabled",
+            }
+        )
+    }
+}
+
 impl From<bool> for UnsafeFixes {
     fn from(value: bool) -> Self {
         if value {
@@ -178,6 +202,19 @@ impl FilePattern {
     }
 }
 
+impl Display for FilePattern {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{:?}",
+            match self {
+                Self::Builtin(pattern) => pattern,
+                Self::User(pattern, _) => pattern.as_str(),
+            }
+        )
+    }
+}
+
 impl FromStr for FilePattern {
     type Err = anyhow::Error;
 
@@ -192,9 +229,14 @@ impl FromStr for FilePattern {
 pub struct FilePatternSet {
     set: GlobSet,
     cache_key: u64,
+    // This field is only for displaying the internals
+    // of `set`.
+    #[allow(clippy::used_underscore_binding)]
+    _set_internals: Vec<FilePattern>,
 }
 
 impl FilePatternSet {
+    #[allow(clippy::used_underscore_binding)]
     pub fn try_from_iter<I>(patterns: I) -> Result<Self, anyhow::Error>
     where
         I: IntoIterator<Item = FilePattern>,
@@ -202,7 +244,10 @@ impl FilePatternSet {
         let mut builder = GlobSetBuilder::new();
         let mut hasher = CacheKeyHasher::new();
 
+        let mut _set_internals = vec![];
+
         for pattern in patterns {
+            _set_internals.push(pattern.clone());
             pattern.cache_key(&mut hasher);
             pattern.add_to(&mut builder)?;
         }
@@ -212,10 +257,26 @@ impl FilePatternSet {
         Ok(FilePatternSet {
             set,
             cache_key: hasher.finish(),
+            _set_internals,
         })
     }
 }
 
+impl Display for FilePatternSet {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        if self._set_internals.is_empty() {
+            write!(f, "[]")?;
+        } else {
+            writeln!(f, "[")?;
+            for pattern in &self._set_internals {
+                writeln!(f, "\t{pattern},")?;
+            }
+            write!(f, "]")?;
+        }
+        Ok(())
+    }
+}
+
 impl Deref for FilePatternSet {
     type Target = GlobSet;
 
@@ -395,6 +456,19 @@ impl ExtensionMapping {
     }
 }
 
+impl Display for ExtensionMapping {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        display_settings! {
+            formatter = f,
+            namespace = "linter.extension",
+            fields = [
+                self.mapping | debug
+            ]
+        }
+        Ok(())
+    }
+}
+
 impl From<FxHashMap<String, Language>> for ExtensionMapping {
     fn from(value: FxHashMap<String, Language>) -> Self {
         Self { mapping: value }
@@ -429,6 +503,23 @@ pub enum SerializationFormat {
     Sarif,
 }
 
+impl Display for SerializationFormat {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Text => write!(f, "text"),
+            Self::Json => write!(f, "json"),
+            Self::JsonLines => write!(f, "json_lines"),
+            Self::Junit => write!(f, "junit"),
+            Self::Grouped => write!(f, "grouped"),
+            Self::Github => write!(f, "github"),
+            Self::Gitlab => write!(f, "gitlab"),
+            Self::Pylint => write!(f, "pylint"),
+            Self::Azure => write!(f, "azure"),
+            Self::Sarif => write!(f, "sarif"),
+        }
+    }
+}
+
 impl Default for SerializationFormat {
     fn default() -> Self {
         Self::Text
@@ -468,3 +559,55 @@ impl Deref for Version {
 /// [`fnmatch`](https://docs.python.org/3/library/fnmatch.html) for
 /// pattern matching.
 pub type IdentifierPattern = glob::Pattern;
+
+#[derive(Debug, CacheKey, Default)]
+pub struct PerFileIgnores {
+    // Ordered as (absolute path matcher, basename matcher, rules)
+    ignores: Vec<(GlobMatcher, GlobMatcher, RuleSet)>,
+}
+
+impl PerFileIgnores {
+    /// Given a list of patterns, create a `GlobSet`.
+    pub fn resolve(per_file_ignores: Vec<PerFileIgnore>) -> Result<Self> {
+        let ignores: Result<Vec<_>> = per_file_ignores
+            .into_iter()
+            .map(|per_file_ignore| {
+                // Construct absolute path matcher.
+                let absolute =
+                    Glob::new(&per_file_ignore.absolute.to_string_lossy())?.compile_matcher();
+
+                // Construct basename matcher.
+                let basename = Glob::new(&per_file_ignore.basename)?.compile_matcher();
+
+                Ok((absolute, basename, per_file_ignore.rules))
+            })
+            .collect();
+        Ok(Self { ignores: ignores? })
+    }
+}
+
+impl Display for PerFileIgnores {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        if self.is_empty() {
+            write!(f, "{{}}")?;
+        } else {
+            writeln!(f, "{{")?;
+            for (absolute, basename, rules) in &self.ignores {
+                writeln!(
+                    f,
+                    "\t{{ absolute = {absolute:#?}, basename = {basename:#?}, rules = {rules} }},"
+                )?;
+            }
+            write!(f, "}}")?;
+        }
+        Ok(())
+    }
+}
+
+impl Deref for PerFileIgnores {
+    type Target = Vec<(GlobMatcher, GlobMatcher, RuleSet)>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.ignores
+    }
+}

crates/ruff_python_formatter/src/options.rs

@@ -2,6 +2,7 @@ use ruff_formatter::printer::{LineEnding, PrinterOptions, SourceMapGeneration};
 use ruff_formatter::{FormatOptions, IndentStyle, IndentWidth, LineWidth};
 use ruff_macros::CacheKey;
 use ruff_python_ast::PySourceType;
+use std::fmt;
 use std::path::Path;
 use std::str::FromStr;
 
@@ -241,6 +242,16 @@ pub enum QuoteStyle {
     Preserve,
 }
 
+impl fmt::Display for QuoteStyle {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Single => write!(f, "single"),
+            Self::Double => write!(f, "double"),
+            Self::Preserve => write!(f, "preserve"),
+        }
+    }
+}
+
 impl FromStr for QuoteStyle {
     type Err = &'static str;
 
@@ -277,6 +288,15 @@ impl MagicTrailingComma {
     }
 }
 
+impl fmt::Display for MagicTrailingComma {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Respect => write!(f, "respect"),
+            Self::Ignore => write!(f, "ignore"),
+        }
+    }
+}
+
 impl FromStr for MagicTrailingComma {
     type Err = &'static str;
 
@@ -306,6 +326,15 @@ impl PreviewMode {
     }
 }
 
+impl fmt::Display for PreviewMode {
+    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"))]
@@ -323,6 +352,15 @@ impl DocstringCode {
     }
 }
 
+impl fmt::Display for DocstringCode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Disabled => write!(f, "disabled"),
+            Self::Enabled => write!(f, "enabled"),
+        }
+    }
+}
+
 #[derive(Copy, Clone, Default, Eq, PartialEq, CacheKey)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "lowercase"))]
@@ -338,8 +376,8 @@ pub enum DocstringCodeLineWidth {
     Dynamic,
 }
 
-impl std::fmt::Debug for DocstringCodeLineWidth {
+impl fmt::Debug for DocstringCodeLineWidth {
-    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             DocstringCodeLineWidth::Fixed(v) => v.value().fmt(f),
             DocstringCodeLineWidth::Dynamic => "dynamic".fmt(f),
@@ -347,6 +385,15 @@ impl std::fmt::Debug for DocstringCodeLineWidth {
     }
 }
 
+impl fmt::Display for DocstringCodeLineWidth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Fixed(width) => width.fmt(f),
+            Self::Dynamic => write!(f, "dynamic"),
+        }
+    }
+}
+
 /// Responsible for deserializing the `DocstringCodeLineWidth::Dynamic`
 /// variant.
 fn deserialize_docstring_code_line_width_dynamic<'de, D>(d: D) -> Result<(), D::Error>

crates/ruff_workspace/src/configuration.rs

@@ -25,12 +25,10 @@ use ruff_linter::rule_selector::{PreviewOptions, Specificity};
 use ruff_linter::rules::pycodestyle;
 use ruff_linter::settings::rule_table::RuleTable;
 use ruff_linter::settings::types::{
-    ExtensionMapping, FilePattern, FilePatternSet, PerFileIgnore, PreviewMode, PythonVersion,
+    ExtensionMapping, FilePattern, FilePatternSet, PerFileIgnore, PerFileIgnores, PreviewMode,
-    SerializationFormat, UnsafeFixes, Version,
+    PythonVersion, SerializationFormat, UnsafeFixes, Version,
-};
-use ruff_linter::settings::{
-    resolve_per_file_ignores, LinterSettings, DEFAULT_SELECTORS, DUMMY_VARIABLE_RGX, TASK_TAGS,
 };
+use ruff_linter::settings::{LinterSettings, DEFAULT_SELECTORS, DUMMY_VARIABLE_RGX, TASK_TAGS};
 use ruff_linter::{
     fs, warn_user, warn_user_once, warn_user_once_by_id, RuleSelector, RUFF_PKG_VERSION,
 };
@@ -260,7 +258,7 @@ impl Configuration {
                 line_length,
                 tab_size: self.indent_width.unwrap_or_default(),
                 namespace_packages: self.namespace_packages.unwrap_or_default(),
-                per_file_ignores: resolve_per_file_ignores(
+                per_file_ignores: PerFileIgnores::resolve(
                     lint.per_file_ignores
                         .unwrap_or_default()
                         .into_iter()

crates/ruff_workspace/src/settings.rs

@@ -1,6 +1,7 @@
 use path_absolutize::path_dedot;
 use ruff_cache::cache_dir;
 use ruff_formatter::{FormatOptions, IndentStyle, IndentWidth, LineWidth};
+use ruff_linter::display_settings;
 use ruff_linter::settings::types::{
     ExtensionMapping, FilePattern, FilePatternSet, SerializationFormat, UnsafeFixes,
 };
@@ -12,6 +13,7 @@ use ruff_python_formatter::{
     QuoteStyle,
 };
 use ruff_source_file::find_newline;
+use std::fmt;
 use std::path::{Path, PathBuf};
 
 #[derive(Debug, CacheKey)]
@@ -55,6 +57,30 @@ impl Default for Settings {
     }
 }
 
+impl fmt::Display for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "\n# General Settings")?;
+        display_settings! {
+            formatter = f,
+            fields = [
+                // We want the quotes and lossy UTF8 conversion for this path, so
+                // using PathBuf's `Debug` formatter suffices.
+                self.cache_dir     | debug,
+                self.fix,
+                self.fix_only,
+                self.output_format,
+                self.show_fixes,
+                self.show_source,
+                self.unsafe_fixes,
+                self.file_resolver | nested,
+                self.linter        | nested,
+                self.formatter     | nested
+            ]
+        }
+        Ok(())
+    }
+}
+
 #[derive(Debug, CacheKey)]
 pub struct FileResolverSettings {
     pub exclude: FilePatternSet,
@@ -66,6 +92,26 @@ pub struct FileResolverSettings {
     pub project_root: PathBuf,
 }
 
+impl fmt::Display for FileResolverSettings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "\n# File Resolver Settings")?;
+        display_settings! {
+            formatter = f,
+            namespace = "file_resolver",
+            fields = [
+                self.exclude,
+                self.extend_exclude,
+                self.force_exclude,
+                self.include,
+                self.extend_include,
+                self.respect_gitignore,
+                self.project_root | debug,
+            ]
+        }
+        Ok(())
+    }
+}
+
 pub(crate) static EXCLUDE: &[FilePattern] = &[
     FilePattern::Builtin(".bzr"),
     FilePattern::Builtin(".direnv"),
@@ -195,6 +241,30 @@ impl Default for FormatterSettings {
     }
 }
 
+impl fmt::Display for FormatterSettings {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "\n# Formatter Settings")?;
+        display_settings! {
+            formatter = f,
+            namespace = "formatter",
+            fields = [
+                self.exclude,
+                self.target_version | debug,
+                self.preview,
+                self.line_width,
+                self.line_ending,
+                self.indent_style,
+                self.indent_width,
+                self.quote_style,
+                self.magic_trailing_comma,
+                self.docstring_code_format,
+                self.docstring_code_line_width,
+            ]
+        }
+        Ok(())
+    }
+}
+
 #[derive(
     Copy, Clone, Debug, Eq, PartialEq, Default, CacheKey, serde::Serialize, serde::Deserialize,
 )]
@@ -216,3 +286,14 @@ pub enum LineEnding {
     /// Line endings will be converted to `\n` on Unix and `\r\n` on Windows.
     Native,
 }
+
+impl fmt::Display for LineEnding {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Auto => write!(f, "auto"),
+            Self::Lf => write!(f, "lf"),
+            Self::CrLf => write!(f, "crlf"),
+            Self::Native => write!(f, "native"),
+        }
+    }
+}