[flake8-bugbear] Add fix for duplicate-value (B033)

crates/ruff_linter/resources/test/fixtures/flake8_bugbear/B033.py

@@ -2,10 +2,28 @@
 # Errors.
 ###
 incorrect_set = {"value1", 23, 5, "value1"}
+incorrect_set = {1, 1, 2}
+incorrect_set_multiline = {
+    "value1",
+    23,
+    5,
+    "value1",
+    # B033
+}
 incorrect_set = {1, 1}
+incorrect_set = {1, 1,}
+incorrect_set = {0, 1, 1,}
+incorrect_set = {0, 1, 1}
+incorrect_set = {
+    0,
+    1,
+    1,
+}
 
 ###
 # Non-errors.
 ###
 correct_set = {"value1", 23, 5}
 correct_set = {5, "5"}
+correct_set = {5}
+correct_set = {}

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

@@ -980,9 +980,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 flake8_pie::rules::unnecessary_spread(checker, dict);
             }
         }
-        Expr::Set(ast::ExprSet { elts, range: _ }) => {
+        Expr::Set(set) => {
             if checker.enabled(Rule::DuplicateValue) {
-                flake8_bugbear::rules::duplicate_value(checker, elts);
+                flake8_bugbear::rules::duplicate_value(checker, set);
             }
         }
         Expr::Yield(_) => {

crates/ruff_linter/src/rules/flake8_bugbear/mod.rs

@@ -12,6 +12,7 @@ mod tests {
 
     use crate::assert_messages;
     use crate::registry::Rule;
+    use crate::settings::types::PreviewMode;
     use crate::settings::LinterSettings;
     use crate::test::test_path;
 
@@ -69,6 +70,24 @@ mod tests {
         Ok(())
     }
 
+    #[test_case(Rule::DuplicateValue, Path::new("B033.py"))]
+    fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
+        let snapshot = format!(
+            "preview__{}_{}",
+            rule_code.noqa_code(),
+            path.to_string_lossy()
+        );
+        let diagnostics = test_path(
+            Path::new("flake8_bugbear").join(path).as_path(),
+            &LinterSettings {
+                preview: PreviewMode::Enabled,
+                ..LinterSettings::for_rule(rule_code)
+            },
+        )?;
+        assert_messages!(snapshot, diagnostics);
+        Ok(())
+    }
+
     #[test]
     fn zip_without_explicit_strict() -> Result<()> {
         let snapshot = "B905.py";

crates/ruff_linter/src/rules/flake8_bugbear/rules/duplicate_value.rs

@@ -1,9 +1,11 @@
-use ruff_python_ast::Expr;
+use anyhow::{Context, Result};
 use rustc_hash::FxHashSet;
 
-use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast as ast;
 use ruff_python_ast::comparable::ComparableExpr;
+use ruff_python_trivia::{SimpleTokenKind, SimpleTokenizer};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
@@ -31,28 +33,82 @@ pub struct DuplicateValue {
 }
 
 impl Violation for DuplicateValue {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         let DuplicateValue { value } = self;
         format!("Sets should not contain duplicate item `{value}`")
     }
+
+    fn fix_title(&self) -> Option<String> {
+        Some(format!("Remove duplicate item"))
+    }
 }
 
 /// B033
-pub(crate) fn duplicate_value(checker: &mut Checker, elts: &Vec<Expr>) {
+pub(crate) fn duplicate_value(checker: &mut Checker, set: &ast::ExprSet) {
     let mut seen_values: FxHashSet<ComparableExpr> = FxHashSet::default();
-    for elt in elts {
+    for (index, elt) in set.elts.iter().enumerate() {
         if elt.is_literal_expr() {
             let comparable_value: ComparableExpr = elt.into();
 
             if !seen_values.insert(comparable_value) {
-                checker.diagnostics.push(Diagnostic::new(
+                let mut diagnostic = Diagnostic::new(
                     DuplicateValue {
                         value: checker.generator().expr(elt),
                     },
                     elt.range(),
-                ));
+                );
+
+                if checker.settings.preview.is_enabled() {
+                    diagnostic.try_set_fix(|| {
+                        remove_member(set, index, checker.locator().contents()).map(Fix::safe_edit)
+                    });
+                }
+
+                checker.diagnostics.push(diagnostic);
             }
         };
     }
 }
+
+/// Remove the member at the given index from the [`ast::ExprSet`].
+fn remove_member(set: &ast::ExprSet, index: usize, source: &str) -> Result<Edit> {
+    if index < set.elts.len() - 1 {
+        // Case 1: the expression is _not_ the last node, so delete from the start of the
+        // expression to the end of the subsequent comma.
+        // Ex) Delete `"a"` in `{"a", "b", "c"}`.
+        let mut tokenizer = SimpleTokenizer::starts_at(set.elts[index].end(), source);
+
+        // Find the trailing comma.
+        tokenizer
+            .find(|token| token.kind == SimpleTokenKind::Comma)
+            .context("Unable to find trailing comma")?;
+
+        // Find the next non-whitespace token.
+        let next = tokenizer
+            .find(|token| {
+                token.kind != SimpleTokenKind::Whitespace && token.kind != SimpleTokenKind::Newline
+            })
+            .context("Unable to find next token")?;
+
+        Ok(Edit::deletion(set.elts[index].start(), next.start()))
+    } else if index > 0 {
+        // Case 2: the expression is the last node, but not the _only_ node, so delete from the
+        // start of the previous comma to the end of the expression.
+        // Ex) Delete `"c"` in `{"a", "b", "c"}`.
+        let mut tokenizer = SimpleTokenizer::starts_at(set.elts[index - 1].end(), source);
+
+        // Find the trailing comma.
+        let comma = tokenizer
+            .find(|token| token.kind == SimpleTokenKind::Comma)
+            .context("Unable to find trailing comma")?;
+
+        Ok(Edit::deletion(comma.start(), set.elts[index].end()))
+    } else {
+        // Case 3: expression is the only node, so delete it.
+        // Ex) Delete `"a"` in `{"a"}`.
+        Ok(Edit::range_deletion(set.elts[index].range()))
+    }
+}

crates/ruff_linter/src/rules/flake8_bugbear/snapshots/ruff_linter__rules__flake8_bugbear__tests__B033_B033.py.snap

@@ -7,17 +7,85 @@ B033.py:4:35: B033 Sets should not contain duplicate item `"value1"`
 3 | ###
 4 | incorrect_set = {"value1", 23, 5, "value1"}
   |                                   ^^^^^^^^ B033
-5 | incorrect_set = {1, 1}
+5 | incorrect_set = {1, 1, 2}
+6 | incorrect_set_multiline = {
   |
+  = help: Remove duplicate item
 
 B033.py:5:21: B033 Sets should not contain duplicate item `1`
   |
 3 | ###
 4 | incorrect_set = {"value1", 23, 5, "value1"}
-5 | incorrect_set = {1, 1}
+5 | incorrect_set = {1, 1, 2}
   |                     ^ B033
-6 | 
-7 | ###
+6 | incorrect_set_multiline = {
+7 |     "value1",
   |
+  = help: Remove duplicate item
+
+B033.py:10:5: B033 Sets should not contain duplicate item `"value1"`
+   |
+ 8 |     23,
+ 9 |     5,
+10 |     "value1",
+   |     ^^^^^^^^ B033
+11 |     # B033
+12 | }
+   |
+   = help: Remove duplicate item
+
+B033.py:13:21: B033 Sets should not contain duplicate item `1`
+   |
+11 |     # B033
+12 | }
+13 | incorrect_set = {1, 1}
+   |                     ^ B033
+14 | incorrect_set = {1, 1,}
+15 | incorrect_set = {0, 1, 1,}
+   |
+   = help: Remove duplicate item
+
+B033.py:14:21: B033 Sets should not contain duplicate item `1`
+   |
+12 | }
+13 | incorrect_set = {1, 1}
+14 | incorrect_set = {1, 1,}
+   |                     ^ B033
+15 | incorrect_set = {0, 1, 1,}
+16 | incorrect_set = {0, 1, 1}
+   |
+   = help: Remove duplicate item
+
+B033.py:15:24: B033 Sets should not contain duplicate item `1`
+   |
+13 | incorrect_set = {1, 1}
+14 | incorrect_set = {1, 1,}
+15 | incorrect_set = {0, 1, 1,}
+   |                        ^ B033
+16 | incorrect_set = {0, 1, 1}
+17 | incorrect_set = {
+   |
+   = help: Remove duplicate item
+
+B033.py:16:24: B033 Sets should not contain duplicate item `1`
+   |
+14 | incorrect_set = {1, 1,}
+15 | incorrect_set = {0, 1, 1,}
+16 | incorrect_set = {0, 1, 1}
+   |                        ^ B033
+17 | incorrect_set = {
+18 |     0,
+   |
+   = help: Remove duplicate item
+
+B033.py:20:5: B033 Sets should not contain duplicate item `1`
+   |
+18 |     0,
+19 |     1,
+20 |     1,
+   |     ^ B033
+21 | }
+   |
+   = help: Remove duplicate item