Make isort's detect-same-package behavior configurable (#6833)

## Summary

Our first-party import detection uses a heuristic that doesn't exist in
isort: if an import appears to be from within the same package as the
containing file, we mark it as first-party. For example, if you have a
directory `./foo/__init__.py`, and you import `from foo import bar` in
`./foo/baz.py`, we'll mark that as first-party. (See:
#1266.)

This is often unnecessary, and arguably should be removed (though it
does have some important use-cases that are otherwise unserved -- I
believe Dagster uses it to ensure that all packages mark imports from
within the same package as first-party, but not imports _across_
different first-party packages)... but it does exist, and it does help
in cases in which the `src` field is not properly configured.

This PR adds an option to turn off this behavior:

```toml
[tool.ruff.isort]
detect-same-package = false
```

This is being introduced to help codebases migrating over from isort
that may want more consistent behavior with their current sorting.

## Test Plan

`cargo test`

crates/ruff/resources/test/fixtures/isort/detect_same_package/foo/bar.py

@@ -0,0 +1,3 @@
+import os
+import pandas
+import foo.baz

crates/ruff/resources/test/fixtures/isort/detect_same_package/pyproject.toml

@@ -0,0 +1,2 @@
+[tool.ruff]
+line-length = 88

crates/ruff/src/rules/flake8_type_checking/rules/typing_only_runtime_import.rs

@@ -283,6 +283,7 @@ pub(crate) fn typing_only_runtime_import(
  None,
  &checker.settings.src,
  checker.package(),
+ checker.settings.isort.detect_same_package,
  &checker.settings.isort.known_modules,
  checker.settings.target_version,
  ) {

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

@@ -69,6 +69,7 @@ pub(crate) fn categorize<'a>(
  level: Option<u32>,
  src: &[PathBuf],
  package: Option<&Path>,
+ detect_same_package: bool,
  known_modules: &'a KnownModules,
  target_version: PythonVersion,
 ) -> &'a ImportSection {
@@ -88,7 +89,7 @@ pub(crate) fn categorize<'a>(
  &ImportSection::Known(ImportType::StandardLibrary),
  Reason::KnownStandardLibrary,
  )
- } else if same_package(package, module_base) {
+ } else if detect_same_package && same_package(package, module_base) {
  (
  &ImportSection::Known(ImportType::FirstParty),
  Reason::SamePackage,
@@ -137,6 +138,7 @@ pub(crate) fn categorize_imports<'a>(
  block: ImportBlock<'a>,
  src: &[PathBuf],
  package: Option<&Path>,
+ detect_same_package: bool,
  known_modules: &'a KnownModules,
  target_version: PythonVersion,
 ) -> BTreeMap<&'a ImportSection, ImportBlock<'a>> {
@@ -148,6 +150,7 @@ pub(crate) fn categorize_imports<'a>(
  None,
  src,
  package,
+ detect_same_package,
  known_modules,
  target_version,
  );
@@ -164,6 +167,7 @@ pub(crate) fn categorize_imports<'a>(
  import_from.level,
  src,
  package,
+ detect_same_package,
  known_modules,
  target_version,
  );
@@ -180,6 +184,7 @@ pub(crate) fn categorize_imports<'a>(
  import_from.level,
  src,
  package,
+ detect_same_package,
  known_modules,
  target_version,
  );
@@ -196,6 +201,7 @@ pub(crate) fn categorize_imports<'a>(
  import_from.level,
  src,
  package,
+ detect_same_package,
  known_modules,
  target_version,
  );

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

@@ -82,6 +82,7 @@ pub(crate) fn format_imports(
  force_to_top: &BTreeSet<String>,
  known_modules: &KnownModules,
  order_by_type: bool,
+ detect_same_package: bool,
  relative_imports_order: RelativeImportsOrder,
  single_line_exclusions: &BTreeSet<String>,
  split_on_trailing_comma: bool,
@@ -129,6 +130,7 @@ pub(crate) fn format_imports(
  force_to_top,
  known_modules,
  order_by_type,
+ detect_same_package,
  relative_imports_order,
  split_on_trailing_comma,
  classes,
@@ -187,6 +189,7 @@ fn format_import_block(
  force_to_top: &BTreeSet<String>,
  known_modules: &KnownModules,
  order_by_type: bool,
+ detect_same_package: bool,
  relative_imports_order: RelativeImportsOrder,
  split_on_trailing_comma: bool,
  classes: &BTreeSet<String>,
@@ -198,7 +201,14 @@ fn format_import_block(
  section_order: &[ImportSection],
 ) -> String {
  // Categorize by type (e.g., first-party vs. third-party).
- let mut block_by_type = categorize_imports(block, src, package, known_modules, target_version);
+ let mut block_by_type = categorize_imports(
+ block,
+ src,
+ package,
+ detect_same_package,
+ known_modules,
+ target_version,
+ );
 
  let mut output = String::new();
 
@@ -1084,4 +1094,38 @@ mod tests {
  assert_messages!(snapshot, diagnostics);
  Ok(())
  }
+
+ #[test]
+ fn detect_same_package() -> Result<()> {
+ let diagnostics = test_path(
+ Path::new("isort/detect_same_package/foo/bar.py"),
+ &Settings {
+ src: vec![],
+ isort: super::settings::Settings {
+ detect_same_package: true,
+ ..super::settings::Settings::default()
+ },
+ ..Settings::for_rule(Rule::UnsortedImports)
+ },
+ )?;
+ assert_messages!(diagnostics);
+ Ok(())
+ }
+
+ #[test]
+ fn no_detect_same_package() -> Result<()> {
+ let diagnostics = test_path(
+ Path::new("isort/detect_same_package/foo/bar.py"),
+ &Settings {
+ src: vec![],
+ isort: super::settings::Settings {
+ detect_same_package: false,
+ ..super::settings::Settings::default()
+ },
+ ..Settings::for_rule(Rule::UnsortedImports)
+ },
+ )?;
+ assert_messages!(diagnostics);
+ Ok(())
+ }
 }

crates/ruff/src/rules/isort/rules/organize_imports.rs

@@ -134,6 +134,7 @@ pub(crate) fn organize_imports(
  &settings.isort.force_to_top,
  &settings.isort.known_modules,
  settings.isort.order_by_type,
+ settings.isort.detect_same_package,
  settings.isort.relative_imports_order,
  &settings.isort.single_line_exclusions,
  settings.isort.split_on_trailing_comma,

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

@@ -305,6 +305,21 @@ pub struct Options {
  )]
  /// Override in which order the sections should be output. Can be used to move custom sections.
  pub section_order: Option<Vec<ImportSection>>,
+ #[option(
+ default = r#"true"#,
+ value_type = "bool",
+ example = r#"
+ detect-same-package = false
+ "#
+ )]
+ /// Whether to automatically mark imports from within the same package as first-party.
+ /// For example, when `detect-same-package = true`, then when analyzing files within the
+ /// `foo` package, any imports from within the `foo` package will be considered first-party.
+ ///
+ /// This heuristic is often unnecessary when `src` is configured to detect all first-party
+ /// sources; however, if `src` is _not_ configured, this heuristic can be useful to detect
+ /// first-party imports from _within_ (but not _across_) first-party packages.
+ pub detect_same_package: Option<bool>,
  // Tables are required to go last.
  #[option(
  default = "{}",
@@ -331,6 +346,7 @@ pub struct Settings {
  pub force_wrap_aliases: bool,
  pub force_to_top: BTreeSet<String>,
  pub known_modules: KnownModules,
+ pub detect_same_package: bool,
  pub order_by_type: bool,
  pub relative_imports_order: RelativeImportsOrder,
  pub single_line_exclusions: BTreeSet<String>,
@@ -352,6 +368,7 @@ impl Default for Settings {
  combine_as_imports: false,
  force_single_line: false,
  force_sort_within_sections: false,
+ detect_same_package: true,
  case_sensitive: false,
  force_wrap_aliases: false,
  force_to_top: BTreeSet::new(),
@@ -509,6 +526,7 @@ impl TryFrom<Options> for Settings {
  force_sort_within_sections: options.force_sort_within_sections.unwrap_or(false),
  case_sensitive: options.case_sensitive.unwrap_or(false),
  force_wrap_aliases: options.force_wrap_aliases.unwrap_or(false),
+ detect_same_package: options.detect_same_package.unwrap_or(true),
  force_to_top: BTreeSet::from_iter(options.force_to_top.unwrap_or_default()),
  known_modules: KnownModules::new(
  known_first_party,
@@ -595,6 +613,7 @@ impl From<Settings> for Options {
  force_sort_within_sections: Some(settings.force_sort_within_sections),
  case_sensitive: Some(settings.case_sensitive),
  force_wrap_aliases: Some(settings.force_wrap_aliases),
+ detect_same_package: Some(settings.detect_same_package),
  force_to_top: Some(settings.force_to_top.into_iter().collect()),
  known_first_party: Some(
  settings

crates/ruff/src/rules/isort/snapshots/ruff__rules__isort__tests__detect_same_package.snap

@@ -0,0 +1,19 @@
+---
+source: crates/ruff/src/rules/isort/mod.rs
+---
+bar.py:1:1: I001 [*] Import block is un-sorted or un-formatted
+ |
+1 | / import os
+2 | | import pandas
+3 | | import foo.baz
+ |
+ = help: Organize imports
+
+ℹ Fix
+1 1 | import os
+ 2 |+
+2 3 | import pandas
+ 4 |+
+3 5 | import foo.baz
+
+

crates/ruff/src/rules/isort/snapshots/ruff__rules__isort__tests__no_detect_same_package.snap

@@ -0,0 +1,19 @@
+---
+source: crates/ruff/src/rules/isort/mod.rs
+---
+bar.py:1:1: I001 [*] Import block is un-sorted or un-formatted
+ |
+1 | / import os
+2 | | import pandas
+3 | | import foo.baz
+ |
+ = help: Organize imports
+
+ℹ Fix
+1 1 | import os
+2 |-import pandas
+ 2 |+
+3 3 | import foo.baz
+ 4 |+import pandas
+
+