Allow Python 3.15 as valid target-version value in preview (#22419)

crates/ruff_linter/src/linter.rs

@@ -26,6 +26,7 @@ use crate::doc_lines::{doc_lines_from_ast, doc_lines_from_tokens};
 use crate::fix::{FixResult, fix_file};
 use crate::noqa::add_noqa;
 use crate::package::PackageRoot;
+use crate::preview::is_py315_support_enabled;
 use crate::registry::Rule;
 #[cfg(any(feature = "test-rules", test))]
 use crate::rules::ruff::rules::test_rules::{self, TEST_RULES, TestRule};
@@ -33,7 +34,7 @@ use crate::settings::types::UnsafeFixes;
 use crate::settings::{LinterSettings, TargetVersion, flags};
 use crate::source_kind::SourceKind;
 use crate::suppression::Suppressions;
-use crate::{Locator, directives, fs};
+use crate::{Locator, directives, fs, warn_user_once};
 
 pub(crate) mod float;
 
@@ -450,6 +451,14 @@ pub fn lint_only(
 ) -> LinterResult {
     let target_version = settings.resolve_target_version(path);
 
+    if matches!(target_version.linter_version(), PythonVersion::PY315)
+        && !is_py315_support_enabled(settings)
+    {
+        warn_user_once!(
+            "Support for Python 3.15 is under development and may be unstable. Enable `preview` to remove this warning."
+        );
+    }
+
     let parsed = source.into_parsed(source_kind, source_type, target_version.parser_version());
 
     // Map row and column locations to byte slices (lazily).
@@ -555,6 +564,14 @@ pub fn lint_fix<'a>(
 
     let target_version = settings.resolve_target_version(path);
 
+    if matches!(target_version.linter_version(), PythonVersion::PY315)
+        && !is_py315_support_enabled(settings)
+    {
+        warn_user_once!(
+            "Support for Python 3.15 is under development and may be unstable. Enable `preview` to remove this warning."
+        );
+    }
+
     // Continuously fix until the source code stabilizes.
     loop {
         // Parse once.

crates/ruff_linter/src/preview.rs

@@ -296,3 +296,8 @@ pub(crate) const fn is_s310_resolve_string_literal_bindings_enabled(
 pub(crate) const fn is_range_suppressions_enabled(settings: &LinterSettings) -> bool {
     settings.preview.is_enabled()
 }
+
+// https://github.com/astral-sh/ruff/pull/22419
+pub(crate) const fn is_py315_support_enabled(settings: &LinterSettings) -> bool {
+    settings.preview.is_enabled()
+}

crates/ruff_linter/src/settings/types.rs

@@ -36,6 +36,7 @@ pub enum PythonVersion {
     Py312,
     Py313,
     Py314,
+    Py315,
 }
 
 impl Default for PythonVersion {
@@ -58,6 +59,7 @@ impl TryFrom<ast::PythonVersion> for PythonVersion {
             ast::PythonVersion::PY312 => Ok(Self::Py312),
             ast::PythonVersion::PY313 => Ok(Self::Py313),
             ast::PythonVersion::PY314 => Ok(Self::Py314),
+            ast::PythonVersion::PY315 => Ok(Self::Py315),
             _ => Err(format!("unrecognized python version {value}")),
         }
     }
@@ -88,6 +90,7 @@ impl PythonVersion {
             Self::Py312 => (3, 12),
             Self::Py313 => (3, 13),
             Self::Py314 => (3, 14),
+            Self::Py315 => (3, 15),
         }
     }
 }

crates/ruff_python_ast/src/python_version.rs

@@ -35,6 +35,10 @@ impl PythonVersion {
         major: 3,
         minor: 14,
     };
+    pub const PY315: PythonVersion = PythonVersion {
+        major: 3,
+        minor: 15,
+    };
 
     pub fn iter() -> impl Iterator<Item = PythonVersion> {
         [
@@ -46,6 +50,7 @@ impl PythonVersion {
             PythonVersion::PY312,
             PythonVersion::PY313,
             PythonVersion::PY314,
+            PythonVersion::PY315,
         ]
         .into_iter()
     }
@@ -61,7 +66,7 @@ impl PythonVersion {
 
     /// The latest Python version supported in preview
     pub fn latest_preview() -> Self {
-        let latest_preview = Self::PY314;
+        let latest_preview = Self::PY315;
         debug_assert!(latest_preview >= Self::latest());
         latest_preview
     }

docs/configuration.md

@@ -610,7 +610,7 @@ Options:
           RUFF_OUTPUT_FILE=]
       --target-version <TARGET_VERSION>
           The minimum Python version that should be supported [possible values:
-          py37, py38, py39, py310, py311, py312, py313, py314]
+          py37, py38, py39, py310, py311, py312, py313, py314, py315]
       --preview
           Enable preview mode; checks will include unstable rules and fixes.
           Use `--no-preview` to disable
@@ -726,7 +726,7 @@ Options:
           notebooks, use `--extension ipy:ipynb`
       --target-version <TARGET_VERSION>
           The minimum Python version that should be supported [possible values:
-          py37, py38, py39, py310, py311, py312, py313, py314]
+          py37, py38, py39, py310, py311, py312, py313, py314, py315]
       --preview
           Enable preview mode; enables unstable formatting. Use `--no-preview`
           to disable

ruff.schema.json

@@ -2884,7 +2884,8 @@
         "py311",
         "py312",
         "py313",
-        "py314"
+        "py314",
+        "py315"
       ]
     },
     "Quote": {

ty.schema.json

@@ -312,6 +312,10 @@
         {
           "description": "Python 3.14",
           "const": "3.14"
+        },
+        {
+          "description": "Python 3.15",
+          "const": "3.15"
         }
       ]
     },