Add a fix for redefinition-while-unused

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

@@ -1,10 +1,11 @@
-use ruff_diagnostics::Diagnostic;
+use ruff_diagnostics::{Diagnostic, Fix};
 use ruff_python_semantic::analyze::visibility;
-use ruff_python_semantic::{Binding, BindingKind, ScopeKind};
+use ruff_python_semantic::{Binding, BindingKind, Imported, ScopeKind};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
 use crate::codes::Rule;
+use crate::fix;
 use crate::rules::{
     flake8_pyi, flake8_type_checking, flake8_unused_arguments, pyflakes, pylint, ruff,
 };
@@ -247,9 +248,31 @@ pub(crate) fn deferred_scopes(checker: &mut Checker) {
                         },
                         binding.range(),
                     );
+
                     if let Some(range) = binding.parent_range(&checker.semantic) {
                         diagnostic.set_parent(range.start());
                     }
+
+                    if let Some(import) = binding.as_any_import() {
+                        if let Some(source) = binding.source {
+                            diagnostic.try_set_fix(|| {
+                                let statement = checker.semantic().statement(source);
+                                let parent = checker.semantic().parent_statement(source);
+                                let edit = fix::edits::remove_unused_imports(
+                                    std::iter::once(import.member_name().as_ref()),
+                                    statement,
+                                    parent,
+                                    checker.locator(),
+                                    checker.stylist(),
+                                    checker.indexer(),
+                                )?;
+                                Ok(Fix::unsafe_edit(edit).isolate(Checker::isolation(
+                                    checker.semantic().parent_statement_id(source),
+                                )))
+                            });
+                        }
+                    }
+
                     diagnostics.push(diagnostic);
                 }
             }

crates/ruff_linter/src/rules/pyflakes/rules/redefined_while_unused.rs

@@ -1,4 +1,4 @@
-use ruff_diagnostics::Violation;
+use ruff_diagnostics::{FixAvailability, Violation};
 use ruff_macros::{derive_message_formats, violation};
 use ruff_source_file::SourceRow;
 
@@ -22,16 +22,40 @@ use ruff_source_file::SourceRow;
 /// import foo
 /// import bar
 /// ```
+///
+/// ## Fix safety
+/// This rule's fix is marked as unsafe, as removing a redefinition across
+/// branches or scopes may change the behavior of the program in subtle
+/// ways.
+///
+/// For example:
+/// ```python
+/// import module
+///
+/// x = int(input())
+///
+/// if x > 0:
+///     from package import module
+/// ```
+///
+/// Removing the redefinition would change the `module` binding when `x > 0`.
 #[violation]
 pub struct RedefinedWhileUnused {
     pub name: String,
     pub row: SourceRow,
 }
 
 impl Violation for RedefinedWhileUnused {
+    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
+
     #[derive_message_formats]
     fn message(&self) -> String {
         let RedefinedWhileUnused { name, row } = self;
         format!("Redefinition of unused `{name}` from {row}")
     }
+
+    fn fix_title(&self) -> Option<String> {
+        let RedefinedWhileUnused { name, .. } = self;
+        Some(format!("Remove definition: `{name}`"))
+    }
 }

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_0.py.snap

@@ -7,5 +7,6 @@ F811_0.py:10:5: F811 Redefinition of unused `bar` from line 6
    |     ^^^ F811
 11 |     pass
    |
+   = help: Remove definition: `bar`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_1.py.snap

@@ -1,10 +1,15 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_1.py:1:25: F811 Redefinition of unused `FU` from line 1
+F811_1.py:1:25: F811 [*] Redefinition of unused `FU` from line 1
   |
 1 | import fu as FU, bar as FU
   |                         ^^ F811
   |
+  = help: Remove definition: `FU`
+
+ℹ Unsafe fix
+1   |-import fu as FU, bar as FU
+  1 |+import fu as FU
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_12.py.snap

@@ -1,13 +1,22 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_12.py:6:20: F811 Redefinition of unused `mixer` from line 2
+F811_12.py:6:20: F811 [*] Redefinition of unused `mixer` from line 2
   |
 4 |     pass
 5 | else:
 6 |     from bb import mixer
   |                    ^^^^^ F811
 7 | mixer(123)
   |
+  = help: Remove definition: `mixer`
+
+ℹ Unsafe fix
+3 3 | except ImportError:
+4 4 |     pass
+5 5 | else:
+6   |-    from bb import mixer
+  6 |+    pass
+7 7 | mixer(123)
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_15.py.snap

@@ -7,5 +7,6 @@ F811_15.py:4:5: F811 Redefinition of unused `fu` from line 1
   |     ^^ F811
 5 |     pass
   |
+  = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_16.py.snap

@@ -9,5 +9,6 @@ F811_16.py:8:13: F811 Redefinition of unused `fu` from line 3
   |             ^^ F811
 9 |             pass
   |
+  = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_17.py.snap

@@ -1,14 +1,24 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_17.py:6:12: F811 Redefinition of unused `fu` from line 2
+F811_17.py:6:12: F811 [*] Redefinition of unused `fu` from line 2
   |
 5 | def bar():
 6 |     import fu
   |            ^^ F811
 7 | 
 8 |     def baz():
   |
+  = help: Remove definition: `fu`
+
+ℹ Unsafe fix
+3 3 | 
+4 4 | 
+5 5 | def bar():
+6   |-    import fu
+7 6 | 
+8 7 |     def baz():
+9 8 |         def fu():
 
 F811_17.py:9:13: F811 Redefinition of unused `fu` from line 6
    |
@@ -17,5 +27,6 @@ F811_17.py:9:13: F811 Redefinition of unused `fu` from line 6
    |             ^^ F811
 10 |             pass
    |
+   = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_2.py.snap

@@ -1,10 +1,15 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_2.py:1:34: F811 Redefinition of unused `FU` from line 1
+F811_2.py:1:34: F811 [*] Redefinition of unused `FU` from line 1
   |
 1 | from moo import fu as FU, bar as FU
   |                                  ^^ F811
   |
+  = help: Remove definition: `FU`
+
+ℹ Unsafe fix
+1   |-from moo import fu as FU, bar as FU
+  1 |+from moo import fu as FU
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_21.py.snap

@@ -1,13 +1,25 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_21.py:32:5: F811 Redefinition of unused `Sequence` from line 26
+F811_21.py:32:5: F811 [*] Redefinition of unused `Sequence` from line 26
    |
 30 | from typing import (
 31 |     List,  # noqa: F811
 32 |     Sequence,
    |     ^^^^^^^^ F811
 33 | )
    |
+   = help: Remove definition: `Sequence`
+
+ℹ Unsafe fix
+29 29 | # This should ignore the first error.
+30 30 | from typing import (
+31 31 |     List,  # noqa: F811
+32    |-    Sequence,
+33    |-)
+   32 |+    )
+34 33 | 
+35 34 | # This should ignore both errors.
+36 35 | from typing import (  # noqa
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_23.py.snap

@@ -1,11 +1,18 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_23.py:4:15: F811 Redefinition of unused `foo` from line 3
+F811_23.py:4:15: F811 [*] Redefinition of unused `foo` from line 3
   |
 3 | import foo as foo
 4 | import bar as foo
   |               ^^^ F811
   |
+  = help: Remove definition: `foo`
+
+ℹ Unsafe fix
+1 1 | """Test that shadowing an explicit re-export produces a warning."""
+2 2 | 
+3 3 | import foo as foo
+4   |-import bar as foo
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_26.py.snap

@@ -9,5 +9,6 @@ F811_26.py:5:9: F811 Redefinition of unused `func` from line 2
   |         ^^^^ F811
 6 |         pass
   |
+  = help: Remove definition: `func`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_3.py.snap

@@ -6,5 +6,6 @@ F811_3.py:1:12: F811 Redefinition of unused `fu` from line 1
 1 | import fu; fu = 3
   |            ^^ F811
   |
+  = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_4.py.snap

@@ -6,5 +6,6 @@ F811_4.py:1:12: F811 Redefinition of unused `fu` from line 1
 1 | import fu; fu, bar = 3
   |            ^^ F811
   |
+  = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_5.py.snap

@@ -6,5 +6,6 @@ F811_5.py:1:13: F811 Redefinition of unused `fu` from line 1
 1 | import fu; [fu, bar] = 3
   |             ^^ F811
   |
+  = help: Remove definition: `fu`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_6.py.snap

@@ -1,13 +1,21 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_6.py:6:12: F811 Redefinition of unused `os` from line 5
+F811_6.py:6:12: F811 [*] Redefinition of unused `os` from line 5
   |
 4 | if i == 1:
 5 |     import os
 6 |     import os
   |            ^^ F811
 7 | os.path
   |
+  = help: Remove definition: `os`
+
+ℹ Unsafe fix
+3 3 | i = 2
+4 4 | if i == 1:
+5 5 |     import os
+6   |-    import os
+7 6 | os.path
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F811_F811_8.py.snap

@@ -1,7 +1,7 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F811_8.py:5:12: F811 Redefinition of unused `os` from line 4
+F811_8.py:5:12: F811 [*] Redefinition of unused `os` from line 4
   |
 3 | try:
 4 |     import os
@@ -10,5 +10,15 @@ F811_8.py:5:12: F811 Redefinition of unused `os` from line 4
 6 | except:
 7 |     pass
   |
+  = help: Remove definition: `os`
+
+ℹ Unsafe fix
+2 2 | 
+3 3 | try:
+4 4 |     import os
+5   |-    import os
+6 5 | except:
+7 6 |     pass
+8 7 | os.path
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__del_shadowed_global_import_in_local_scope.snap

@@ -17,13 +17,23 @@ source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 4 3 | def f():
 5 4 |     import os
 
-<filename>:5:12: F811 Redefinition of unused `os` from line 2
+<filename>:5:12: F811 [*] Redefinition of unused `os` from line 2
   |
 4 | def f():
 5 |     import os
   |            ^^ F811
 6 | 
 7 |     # Despite this `del`, `import os` in `f` should still be flagged as shadowing an unused
   |
+  = help: Remove definition: `os`
+
+ℹ Unsafe fix
+2 2 | import os
+3 3 | 
+4 4 | def f():
+5   |-    import os
+6 5 | 
+7 6 |     # Despite this `del`, `import os` in `f` should still be flagged as shadowing an unused
+8 7 |     # import.
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__del_shadowed_import_shadow_in_local_scope.snap

@@ -24,5 +24,6 @@ source: crates/ruff_linter/src/rules/pyflakes/mod.rs
   |     ^^ F811
 6 |     print(os)
   |
+  = help: Remove definition: `os`
 
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__del_shadowed_local_import_in_local_scope.snap

@@ -1,7 +1,7 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-<filename>:4:12: F811 Redefinition of unused `os` from line 3
+<filename>:4:12: F811 [*] Redefinition of unused `os` from line 3
   |
 2 | def f():
 3 |     import os
@@ -10,5 +10,15 @@ source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 5 | 
 6 |     # Despite this `del`, `import os` should still be flagged as shadowing an unused
   |
+  = help: Remove definition: `os`
+
+ℹ Unsafe fix
+1 1 | 
+2 2 | def f():
+3 3 |     import os
+4   |-    import os
+5 4 | 
+6 5 |     # Despite this `del`, `import os` should still be flagged as shadowing an unused
+7 6 |     # import.