[pylint] - implement C2701 import-private-name

crates/ruff_linter/resources/test/fixtures/pylint/import_private_name.py

@@ -0,0 +1,13 @@
+from __future__ import annotations  # Ok
+
+from .. import __version__  # Ok
+from .internal import _private  # Ok
+
+import _private  # PLC2701
+import _private as _p  # PLC2701
+from _private import _private  # PLC2701
+from lib import _private  # PLC2701
+from lib import _private as _p  # PLC2701
+from lib._private import _private  # PLC2701
+from lib._private import _private as _p  # PLC2701
+from lib._private import _private, _private as _p  # PLC2701

crates/ruff_linter/src/checkers/ast/analyze/statement.rs

@@ -536,6 +536,9 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
             if checker.enabled(Rule::ImportOutsideTopLevel) {
                 pylint::rules::import_outside_top_level(checker, stmt);
             }
+            if checker.enabled(Rule::ImportPrivateName) {
+                pylint::rules::import_private_name(checker, stmt);
+            }
             if checker.enabled(Rule::GlobalStatement) {
                 for name in names {
                     if let Some(asname) = name.asname.as_ref() {
@@ -715,6 +718,9 @@ pub(crate) fn statement(stmt: &Stmt, checker: &mut Checker) {
             if checker.enabled(Rule::ImportOutsideTopLevel) {
                 pylint::rules::import_outside_top_level(checker, stmt);
             }
+            if checker.enabled(Rule::ImportPrivateName) {
+                pylint::rules::import_private_name(checker, stmt);
+            }
             if checker.enabled(Rule::GlobalStatement) {
                 for name in names {
                     if let Some(asname) = name.asname.as_ref() {

crates/ruff_linter/src/codes.rs

@@ -214,6 +214,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Pylint, "C0415") => (RuleGroup::Preview, rules::pylint::rules::ImportOutsideTopLevel),
         (Pylint, "C2401") => (RuleGroup::Preview, rules::pylint::rules::NonAsciiName),
         (Pylint, "C2403") => (RuleGroup::Preview, rules::pylint::rules::NonAsciiImportName),
+        (Pylint, "C2701") => (RuleGroup::Preview, rules::pylint::rules::ImportPrivateName),
         #[allow(deprecated)]
         (Pylint, "C1901") => (RuleGroup::Nursery, rules::pylint::rules::CompareToEmptyString),
         (Pylint, "C3002") => (RuleGroup::Stable, rules::pylint::rules::UnnecessaryDirectLambdaCall),

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

@@ -62,6 +62,7 @@ mod tests {
         Path::new("global_variable_not_assigned.py")
     )]
     #[test_case(Rule::ImportOutsideTopLevel, Path::new("import_outside_top_level.py"))]
+    #[test_case(Rule::ImportPrivateName, Path::new("import_private_name.py"))]
     #[test_case(Rule::ImportSelf, Path::new("import_self/module.py"))]
     #[test_case(Rule::InvalidAllFormat, Path::new("invalid_all_format.py"))]
     #[test_case(Rule::InvalidAllObject, Path::new("invalid_all_object.py"))]

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

@@ -0,0 +1,103 @@
+use ruff_diagnostics::{Diagnostic, FixAvailability, Violation};
+use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::{self as ast, Stmt};
+use ruff_text_size::Ranged;
+
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Check for imported symbols that have a leading underscore, known as "private" symbols.
+///
+/// ## Why is this bad?
+/// According to [PEP 8], the underscore prefix is used to indicate that a symbol is private.
+/// Private symbols are not meant to be used outside of the module they are defined in.
+///
+/// [PEP 8]: https://peps.python.org/pep-0008/#descriptive-naming-styles
+#[violation]
+pub struct ImportPrivateName {
+    symbol_type: SymbolType,
+}
+
+impl Violation for ImportPrivateName {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::None;
+
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        let ImportPrivateName { symbol_type } = self;
+        match symbol_type {
+            SymbolType::Module => format!("Imported private module"),
+            SymbolType::FromModule => format!("Imported from private module"),
+            SymbolType::Object => format!("Imported private object"),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum SymbolType {
+    Module,
+    FromModule,
+    Object,
+}
+
+/// C2701
+pub(crate) fn import_private_name(checker: &mut Checker, stmt: &Stmt) {
+    match stmt {
+        Stmt::Import(ast::StmtImport { names, .. }) => {
+            for alias in names {
+                if alias.name.as_str().starts_with('_') {
+                    checker.diagnostics.push(Diagnostic::new(
+                        ImportPrivateName {
+                            symbol_type: SymbolType::Module,
+                        },
+                        alias.name.range(),
+                    ));
+                }
+            }
+        }
+        Stmt::ImportFrom(ast::StmtImportFrom {
+            names,
+            module,
+            level,
+            ..
+        }) => {
+            if level.is_some_and(|level| level > 0) {
+                // allow relative private imports, common in libs
+                return;
+            }
+
+            if let Some(identifier) = module {
+                if identifier == "__future__" {
+                    return;
+                }
+
+                if identifier.starts_with('_') {
+                    checker.diagnostics.push(Diagnostic::new(
+                        ImportPrivateName {
+                            symbol_type: SymbolType::Module,
+                        },
+                        identifier.range(),
+                    ));
+                } else if identifier.contains("._") {
+                    checker.diagnostics.push(Diagnostic::new(
+                        ImportPrivateName {
+                            symbol_type: SymbolType::FromModule,
+                        },
+                        identifier.range(),
+                    ));
+                }
+            }
+
+            for alias in names {
+                if alias.name.as_str().starts_with('_') {
+                    checker.diagnostics.push(Diagnostic::new(
+                        ImportPrivateName {
+                            symbol_type: SymbolType::Object,
+                        },
+                        alias.name.range(),
+                    ));
+                }
+            }
+        }
+        _ => {}
+    }
+}

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

@@ -19,6 +19,7 @@ pub(crate) use global_at_module_level::*;
 pub(crate) use global_statement::*;
 pub(crate) use global_variable_not_assigned::*;
 pub(crate) use import_outside_top_level::*;
+pub(crate) use import_private_name::*;
 pub(crate) use import_self::*;
 pub(crate) use invalid_all_format::*;
 pub(crate) use invalid_all_object::*;
@@ -92,6 +93,7 @@ mod global_at_module_level;
 mod global_statement;
 mod global_variable_not_assigned;
 mod import_outside_top_level;
+mod import_private_name;
 mod import_self;
 mod invalid_all_format;
 mod invalid_all_object;

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLC2701_import_private_name.py.snap

@@ -0,0 +1,125 @@
+---
+source: crates/ruff_linter/src/rules/pylint/mod.rs
+---
+import_private_name.py:6:8: PLC2701 Imported private module
+  |
+4 | from .internal import _private  # Ok
+5 | 
+6 | import _private  # PLC2701
+  |        ^^^^^^^^ PLC2701
+7 | import _private as _p  # PLC2701
+8 | from _private import _private  # PLC2701
+  |
+
+import_private_name.py:7:8: PLC2701 Imported private module
+  |
+6 | import _private  # PLC2701
+7 | import _private as _p  # PLC2701
+  |        ^^^^^^^^ PLC2701
+8 | from _private import _private  # PLC2701
+9 | from lib import _private  # PLC2701
+  |
+
+import_private_name.py:8:6: PLC2701 Imported private module
+   |
+ 6 | import _private  # PLC2701
+ 7 | import _private as _p  # PLC2701
+ 8 | from _private import _private  # PLC2701
+   |      ^^^^^^^^ PLC2701
+ 9 | from lib import _private  # PLC2701
+10 | from lib import _private as _p  # PLC2701
+   |
+
+import_private_name.py:8:22: PLC2701 Imported private object
+   |
+ 6 | import _private  # PLC2701
+ 7 | import _private as _p  # PLC2701
+ 8 | from _private import _private  # PLC2701
+   |                      ^^^^^^^^ PLC2701
+ 9 | from lib import _private  # PLC2701
+10 | from lib import _private as _p  # PLC2701
+   |
+
+import_private_name.py:9:17: PLC2701 Imported private object
+   |
+ 7 | import _private as _p  # PLC2701
+ 8 | from _private import _private  # PLC2701
+ 9 | from lib import _private  # PLC2701
+   |                 ^^^^^^^^ PLC2701
+10 | from lib import _private as _p  # PLC2701
+11 | from lib._private import _private  # PLC2701
+   |
+
+import_private_name.py:10:17: PLC2701 Imported private object
+   |
+ 8 | from _private import _private  # PLC2701
+ 9 | from lib import _private  # PLC2701
+10 | from lib import _private as _p  # PLC2701
+   |                 ^^^^^^^^ PLC2701
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+   |
+
+import_private_name.py:11:6: PLC2701 Imported from private module
+   |
+ 9 | from lib import _private  # PLC2701
+10 | from lib import _private as _p  # PLC2701
+11 | from lib._private import _private  # PLC2701
+   |      ^^^^^^^^^^^^ PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |
+
+import_private_name.py:11:26: PLC2701 Imported private object
+   |
+ 9 | from lib import _private  # PLC2701
+10 | from lib import _private as _p  # PLC2701
+11 | from lib._private import _private  # PLC2701
+   |                          ^^^^^^^^ PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |
+
+import_private_name.py:12:6: PLC2701 Imported from private module
+   |
+10 | from lib import _private as _p  # PLC2701
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+   |      ^^^^^^^^^^^^ PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |
+
+import_private_name.py:12:26: PLC2701 Imported private object
+   |
+10 | from lib import _private as _p  # PLC2701
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+   |                          ^^^^^^^^ PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |
+
+import_private_name.py:13:6: PLC2701 Imported from private module
+   |
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |      ^^^^^^^^^^^^ PLC2701
+   |
+
+import_private_name.py:13:26: PLC2701 Imported private object
+   |
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |                          ^^^^^^^^ PLC2701
+   |
+
+import_private_name.py:13:36: PLC2701 Imported private object
+   |
+11 | from lib._private import _private  # PLC2701
+12 | from lib._private import _private as _p  # PLC2701
+13 | from lib._private import _private, _private as _p  # PLC2701
+   |                                    ^^^^^^^^ PLC2701
+   |
+
+