[ruff] Do not remove parens for tuples with starred expressions in Py…

…thon <=3.10 `RUF031` (#12784)

crates/ruff_linter/resources/test/fixtures/ruff/RUF031.py

@@ -28,4 +28,9 @@
 d[(1,)]
 d[()] # empty tuples should be ignored
 d[:,] # slices in the subscript lead to syntax error if parens are added
-d[1,2,:]
+d[1,2,:]
+
+# Should keep these parentheses in
+# Python <=3.10 to avoid syntax error.
+# https://github.com/astral-sh/ruff/issues/12776
+d[(*foo,bar)] 

crates/ruff_linter/resources/test/fixtures/ruff/RUF031_prefer_parens.py

@@ -28,4 +28,9 @@
 d[()] # empty tuples should be ignored
 
 d[:,] # slices in the subscript lead to syntax error if parens are added
-d[1,2,:]
+d[1,2,:]
+
+# Should keep these parentheses in
+# Python <=3.10 to avoid syntax error.
+# https://github.com/astral-sh/ruff/issues/12776
+d[(*foo,bar)] 

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

@@ -84,6 +84,22 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn no_remove_parentheses_starred_expr_py310() -> Result<()> {
+        let diagnostics = test_path(
+            Path::new("ruff/RUF031.py"),
+            &LinterSettings {
+                ruff: super::settings::Settings {
+                    parenthesize_tuple_in_subscript: false,
+                },
+                target_version: PythonVersion::Py310,
+                ..LinterSettings::for_rule(Rule::IncorrectlyParenthesizedTupleInSubscript)
+            },
+        )?;
+        assert_messages!(diagnostics);
+        Ok(())
+    }
+
     #[test_case(Path::new("RUF013_0.py"))]
     #[test_case(Path::new("RUF013_1.py"))]
     fn implicit_optional_py39(path: &Path) -> Result<()> {

crates/ruff_linter/src/rules/ruff/rules/incorrectly_parenthesized_tuple_in_subscript.rs

@@ -3,7 +3,7 @@ use ruff_macros::{derive_message_formats, violation};
 use ruff_python_ast::{Expr, ExprSubscript};
 use ruff_text_size::Ranged;
 
-use crate::checkers::ast::Checker;
+use crate::{checkers::ast::Checker, settings::types::PythonVersion};
 
 /// ## What it does
 /// Checks for consistent style regarding whether nonempty tuples in subscripts
@@ -68,6 +68,16 @@ pub(crate) fn subscript_with_parenthesized_tuple(checker: &mut Checker, subscrip
     if prefer_parentheses && tuple_subscript.elts.iter().any(Expr::is_slice_expr) {
         return;
     }
+    // Removing parentheses in the presence of unpacking leads
+    // to a syntax error in Python 3.10.
+    // This is no longer a syntax error starting in Python 3.11
+    // see https://peps.python.org/pep-0646/#change-1-star-expressions-in-indexes
+    if checker.settings.target_version <= PythonVersion::Py310
+        && !prefer_parentheses
+        && tuple_subscript.elts.iter().any(Expr::is_starred_expr)
+    {
+        return;
+    }
     let locator = checker.locator();
     let source_range = subscript.slice.range();
     let new_source = if prefer_parentheses {

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__RUF031_RUF031.py.snap

@@ -169,3 +169,19 @@ RUF031.py:28:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
 29 29 | d[()] # empty tuples should be ignored
 30 30 | d[:,] # slices in the subscript lead to syntax error if parens are added
 31 31 | d[1,2,:]
+
+RUF031.py:36:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+34 | # Python <=3.10 to avoid syntax error.
+35 | # https://github.com/astral-sh/ruff/issues/12776
+36 | d[(*foo,bar)] 
+   |   ^^^^^^^^^^ RUF031
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+33 33 | # Should keep these parentheses in
+34 34 | # Python <=3.10 to avoid syntax error.
+35 35 | # https://github.com/astral-sh/ruff/issues/12776
+36    |-d[(*foo,bar)] 
+   36 |+d[*foo,bar]

crates/ruff_linter/src/rules/ruff/snapshots/ruff_linter__rules__ruff__tests__no_remove_parentheses_starred_expr_py310.snap

@@ -0,0 +1,171 @@
+---
+source: crates/ruff_linter/src/rules/ruff/mod.rs
+---
+RUF031.py:2:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+  |
+1 | d = {(1,2):"a",(3,4):"b",(5,6,7):"c",(8,):"d"}
+2 | d[(1,2)]
+  |   ^^^^^ RUF031
+3 | d[(
+4 |     1,
+  |
+  = help: Remove the parentheses.
+
+ℹ Safe fix
+1 1 | d = {(1,2):"a",(3,4):"b",(5,6,7):"c",(8,):"d"}
+2   |-d[(1,2)]
+  2 |+d[1,2]
+3 3 | d[(
+4 4 |     1,
+5 5 |     2
+
+RUF031.py:3:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+  |
+1 |   d = {(1,2):"a",(3,4):"b",(5,6,7):"c",(8,):"d"}
+2 |   d[(1,2)]
+3 |   d[(
+  |  ___^
+4 | |     1,
+5 | |     2
+6 | | )]
+  | |_^ RUF031
+7 |   d[
+8 |       1,
+  |
+  = help: Remove the parentheses.
+
+ℹ Safe fix
+1 1 | d = {(1,2):"a",(3,4):"b",(5,6,7):"c",(8,):"d"}
+2 2 | d[(1,2)]
+3   |-d[(
+  3 |+d[
+4 4 |     1,
+5 5 |     2
+6   |-)]
+  6 |+]
+7 7 | d[
+8 8 |     1,
+9 9 |     2
+
+RUF031.py:11:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+ 9 |     2
+10 | ]
+11 | d[(2,4)]
+   |   ^^^^^ RUF031
+12 | d[(5,6,7)]
+13 | d[(8,)]
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+8  8  |     1,
+9  9  |     2
+10 10 | ]
+11    |-d[(2,4)]
+   11 |+d[2,4]
+12 12 | d[(5,6,7)]
+13 13 | d[(8,)]
+14 14 | d[tuple(1,2)]
+
+RUF031.py:12:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+10 | ]
+11 | d[(2,4)]
+12 | d[(5,6,7)]
+   |   ^^^^^^^ RUF031
+13 | d[(8,)]
+14 | d[tuple(1,2)]
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+9  9  |     2
+10 10 | ]
+11 11 | d[(2,4)]
+12    |-d[(5,6,7)]
+   12 |+d[5,6,7]
+13 13 | d[(8,)]
+14 14 | d[tuple(1,2)]
+15 15 | d[tuple(8)]
+
+RUF031.py:13:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+11 | d[(2,4)]
+12 | d[(5,6,7)]
+13 | d[(8,)]
+   |   ^^^^ RUF031
+14 | d[tuple(1,2)]
+15 | d[tuple(8)]
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+10 10 | ]
+11 11 | d[(2,4)]
+12 12 | d[(5,6,7)]
+13    |-d[(8,)]
+   13 |+d[8,]
+14 14 | d[tuple(1,2)]
+15 15 | d[tuple(8)]
+16 16 | d[1,2]
+
+RUF031.py:20:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+18 | d[5,6,7]
+19 | e = {((1,2),(3,4)):"a"}
+20 | e[((1,2),(3,4))]
+   |   ^^^^^^^^^^^^^ RUF031
+21 | e[(1,2),(3,4)]
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+17 17 | d[3,4]
+18 18 | d[5,6,7]
+19 19 | e = {((1,2),(3,4)):"a"}
+20    |-e[((1,2),(3,4))]
+21 20 | e[(1,2),(3,4)]
+   21 |+e[(1,2),(3,4)]
+22 22 | 
+23 23 | token_features[
+24 24 |     (window_position, feature_name)
+
+RUF031.py:24:5: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+23 | token_features[
+24 |     (window_position, feature_name)
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF031
+25 | ] = self._extract_raw_features_from_token
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+21 21 | e[(1,2),(3,4)]
+22 22 | 
+23 23 | token_features[
+24    |-    (window_position, feature_name)
+   24 |+    window_position, feature_name
+25 25 | ] = self._extract_raw_features_from_token
+26 26 | 
+27 27 | d[1,]
+
+RUF031.py:28:3: RUF031 [*] Avoid parentheses for tuples in subscripts.
+   |
+27 | d[1,]
+28 | d[(1,)]
+   |   ^^^^ RUF031
+29 | d[()] # empty tuples should be ignored
+30 | d[:,] # slices in the subscript lead to syntax error if parens are added
+   |
+   = help: Remove the parentheses.
+
+ℹ Safe fix
+25 25 | ] = self._extract_raw_features_from_token
+26 26 | 
+27 27 | d[1,]
+28    |-d[(1,)]
+   28 |+d[1,]
+29 29 | d[()] # empty tuples should be ignored
+30 30 | d[:,] # slices in the subscript lead to syntax error if parens are added
+31 31 | d[1,2,:]