Change default for Python version from 3.8 to 3.9 (#13896)

Co-authored-by: Micha Reiser <[email protected]>

README.md

@@ -238,8 +238,8 @@ exclude = [
 line-length = 88
 indent-width = 4
 
-# Assume Python 3.8
-target-version = "py38"
+# Assume Python 3.9
+target-version = "py39"
 
 [lint]
 # Enable Pyflakes (`F`) and a subset of the pycodestyle (`E`)  codes by default.

crates/red_knot/src/target_version.rs

@@ -46,3 +46,17 @@ impl From<TargetVersion> for red_knot_python_semantic::PythonVersion {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::target_version::TargetVersion;
+    use red_knot_python_semantic::PythonVersion;
+
+    #[test]
+    fn same_default_as_python_version() {
+        assert_eq!(
+            PythonVersion::from(TargetVersion::default()),
+            PythonVersion::default()
+        );
+    }
+}

crates/red_knot_wasm/src/lib.rs

@@ -291,3 +291,17 @@ impl System for WasmSystem {
 fn not_found() -> std::io::Error {
     std::io::Error::new(std::io::ErrorKind::NotFound, "No such file or directory")
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::TargetVersion;
+    use red_knot_python_semantic::PythonVersion;
+
+    #[test]
+    fn same_default_as_python_version() {
+        assert_eq!(
+            PythonVersion::from(TargetVersion::default()),
+            PythonVersion::default()
+        );
+    }
+}

crates/ruff_linter/src/settings/types.rs

@@ -42,10 +42,10 @@ use crate::{display_settings, fs};
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub enum PythonVersion {
     Py37,
+    Py38,
     // Make sure to also change the default for `ruff_python_formatter::PythonVersion`
     // when changing the default here.
     #[default]
-    Py38,
     Py39,
     Py310,
     Py311,
@@ -68,6 +68,10 @@ impl PythonVersion {
         Self::Py313
     }
 
+    pub const fn minimal_supported() -> Self {
+        Self::Py37
+    }
+
     pub const fn as_tuple(&self) -> (u8, u8) {
         match self {
             Self::Py37 => (3, 7),

crates/ruff_python_formatter/resources/test/fixtures/black/cases/context_managers_38.options.json

@@ -0,0 +1 @@
+{"target_version": "py38"}

crates/ruff_python_formatter/resources/test/fixtures/black/cases/context_managers_autodetect_38.options.json

@@ -0,0 +1 @@
+{"target_version": "py38"}