[`flake8-use-pathlib`] Skip single dots for `invalid-pathlib-with-suffix` (`PTH210`) on versions >= 3.14 (#19331)

Skips [invalid-pathlib-with-suffix
(PTH210)](https://docs.astral.sh/ruff/rules/invalid-pathlib-with-suffix/#invalid-pathlib-with-suffix-pth210)
for `.with_suffix(".")` on Python versions 3.14 and greater, as per [the
docs](https://docs.python.org/3.14/library/pathlib.html#pathlib.PurePath.with_suffix).

Progress towards #15506

crates/ruff_linter/resources/test/fixtures/flake8_use_pathlib/PTH210_2.py

@@ -0,0 +1,26 @@
+from pathlib import (
+    Path,
+    PosixPath,
+    PurePath,
+    PurePosixPath,
+    PureWindowsPath,
+    WindowsPath,
+)
+import pathlib
+
+
+path = Path()
+posix_path: pathlib.PosixPath = PosixPath()
+pure_path: PurePath = PurePath()
+pure_posix_path = pathlib.PurePosixPath()
+pure_windows_path: PureWindowsPath = pathlib.PureWindowsPath()
+windows_path: pathlib.WindowsPath = pathlib.WindowsPath()
+
+
+### No Errors
+path.with_suffix(".")
+posix_path.with_suffix(".")
+pure_path.with_suffix(".")
+pure_posix_path.with_suffix(".")
+pure_windows_path.with_suffix(".")
+windows_path.with_suffix(".")

crates/ruff_linter/src/rules/flake8_use_pathlib/mod.rs

@@ -8,6 +8,7 @@ mod tests {
     use std::path::Path;
 
     use anyhow::Result;
+    use ruff_python_ast::PythonVersion;
     use test_case::test_case;
 
     use crate::assert_diagnostics;
@@ -143,4 +144,22 @@ mod tests {
         assert_diagnostics!(snapshot, diagnostics);
         Ok(())
     }
+
+    #[test_case(Rule::InvalidPathlibWithSuffix, Path::new("PTH210_2.py"))]
+    fn pathlib_with_suffix_py314(rule_code: Rule, path: &Path) -> Result<()> {
+        let snapshot = format!(
+            "py314__{}_{}",
+            rule_code.noqa_code(),
+            path.to_string_lossy()
+        );
+        let diagnostics = test_path(
+            Path::new("flake8_use_pathlib").join(path).as_path(),
+            &settings::LinterSettings {
+                unresolved_target_version: PythonVersion::PY314.into(),
+                ..settings::LinterSettings::for_rule(rule_code)
+            },
+        )?;
+        assert_diagnostics!(snapshot, diagnostics);
+        Ok(())
+    }
 }

crates/ruff_linter/src/rules/flake8_use_pathlib/rules/invalid_pathlib_with_suffix.rs

@@ -1,7 +1,7 @@
 use crate::checkers::ast::Checker;
 use crate::{Edit, Fix, FixAvailability, Violation};
 use ruff_macros::{ViolationMetadata, derive_message_formats};
-use ruff_python_ast::{self as ast, StringFlags};
+use ruff_python_ast::{self as ast, PythonVersion, StringFlags};
 use ruff_python_semantic::SemanticModel;
 use ruff_python_semantic::analyze::typing;
 use ruff_text_size::Ranged;
@@ -9,12 +9,13 @@ use ruff_text_size::Ranged;
 /// ## What it does
 /// Checks for `pathlib.Path.with_suffix()` calls where
 /// the given suffix does not have a leading dot
-/// or the given suffix is a single dot `"."`.
+/// or the given suffix is a single dot `"."` and the
+/// Python version is less than 3.14.
 ///
 /// ## Why is this bad?
 /// `Path.with_suffix()` will raise an error at runtime
 /// if the given suffix is not prefixed with a dot
-/// or it is a single dot `"."`.
+/// or, in versions prior to Python 3.14, if it is a single dot `"."`.
 ///
 /// ## Example
 ///
@@ -57,9 +58,6 @@ use ruff_text_size::Ranged;
 /// No fix is offered if the suffix `"."` is given, since the intent is unclear.
 #[derive(ViolationMetadata)]
 pub(crate) struct InvalidPathlibWithSuffix {
-    // TODO: Since "." is a correct suffix in Python 3.14,
-    // we will need to update this rule and documentation
-    // once Ruff supports Python 3.14.
     single_dot: bool,
 }
 
@@ -116,6 +114,13 @@ pub(crate) fn invalid_pathlib_with_suffix(checker: &Checker, call: &ast::ExprCal
     };
 
     let single_dot = string_value == ".";
+
+    // As of Python 3.14, a single dot is considered a valid suffix.
+    // https://docs.python.org/3.14/library/pathlib.html#pathlib.PurePath.with_suffix
+    if single_dot && checker.target_version() >= PythonVersion::PY314 {
+        return;
+    }
+
     let mut diagnostic =
         checker.report_diagnostic(InvalidPathlibWithSuffix { single_dot }, call.range);
     if !single_dot {

crates/ruff_linter/src/rules/flake8_use_pathlib/snapshots/ruff_linter__rules__flake8_use_pathlib__tests__py314__PTH210_PTH210_2.py.snap

@@ -0,0 +1,4 @@
+---
+source: crates/ruff_linter/src/rules/flake8_use_pathlib/mod.rs
+---
+