F841: support fixing unused assignments in tuples by renaming variables

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

@@ -247,6 +247,14 @@ fn remove_unused_variable(binding: &Binding, checker: &Checker) -> Option<Fix> {
                     Some(Fix::unsafe_edit(edit).isolate(isolation))
                 };
             }
+        } else {
+            let name = binding.name(checker.locator());
+            let renamed = format!("_{name}");
+            if checker.settings.dummy_variable_rgx.is_match(&renamed) {
+                let edit = Edit::range_replacement(renamed, binding.range());
+
+                return Some(Fix::unsafe_edit(edit).isolate(isolation));
+            }
         }
     }
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F841_F841_0.py.snap

@@ -57,7 +57,7 @@ F841_0.py:20:5: F841 [*] Local variable `foo` is assigned to but never used
 22 21 | 
 23 22 |     bar = (1, 2)
 
-F841_0.py:21:6: F841 Local variable `a` is assigned to but never used
+F841_0.py:21:6: F841 [*] Local variable `a` is assigned to but never used
    |
 19 | def f():
 20 |     foo = (1, 2)
@@ -68,7 +68,17 @@ F841_0.py:21:6: F841 Local variable `a` is assigned to but never used
    |
    = help: Remove assignment to unused variable `a`
 
-F841_0.py:21:9: F841 Local variable `b` is assigned to but never used
+ℹ Unsafe fix
+18 18 | 
+19 19 | def f():
+20 20 |     foo = (1, 2)
+21    |-    (a, b) = (1, 2)
+   21 |+    (_a, b) = (1, 2)
+22 22 | 
+23 23 |     bar = (1, 2)
+24 24 |     (c, d) = bar
+
+F841_0.py:21:9: F841 [*] Local variable `b` is assigned to but never used
    |
 19 | def f():
 20 |     foo = (1, 2)
@@ -79,6 +89,16 @@ F841_0.py:21:9: F841 Local variable `b` is assigned to but never used
    |
    = help: Remove assignment to unused variable `b`
 
+ℹ Unsafe fix
+18 18 | 
+19 19 | def f():
+20 20 |     foo = (1, 2)
+21    |-    (a, b) = (1, 2)
+   21 |+    (a, _b) = (1, 2)
+22 22 | 
+23 23 |     bar = (1, 2)
+24 24 |     (c, d) = bar
+
 F841_0.py:26:14: F841 [*] Local variable `baz` is assigned to but never used
    |
 24 |     (c, d) = bar

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F841_F841_1.py.snap

@@ -1,22 +1,42 @@
 ---
 source: crates/ruff_linter/src/rules/pyflakes/mod.rs
 ---
-F841_1.py:6:5: F841 Local variable `x` is assigned to but never used
+F841_1.py:6:5: F841 [*] Local variable `x` is assigned to but never used
   |
 5 | def f():
 6 |     x, y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
   |     ^ F841
   |
   = help: Remove assignment to unused variable `x`
 
-F841_1.py:6:8: F841 Local variable `y` is assigned to but never used
+ℹ Unsafe fix
+3 3 | 
+4 4 | 
+5 5 | def f():
+6   |-    x, y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
+  6 |+    _x, y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
+7 7 | 
+8 8 | 
+9 9 | def f():
+
+F841_1.py:6:8: F841 [*] Local variable `y` is assigned to but never used
   |
 5 | def f():
 6 |     x, y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
   |        ^ F841
   |
   = help: Remove assignment to unused variable `y`
 
+ℹ Unsafe fix
+3 3 | 
+4 4 | 
+5 5 | def f():
+6   |-    x, y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
+  6 |+    x, _y = 1, 2  # this triggers F841 as it's just a simple assignment where unpacking isn't needed
+7 7 | 
+8 8 | 
+9 9 | def f():
+
 F841_1.py:16:14: F841 [*] Local variable `coords` is assigned to but never used
    |
 15 | def f():
@@ -53,36 +73,64 @@ F841_1.py:20:5: F841 [*] Local variable `coords` is assigned to but never used
 22 22 | 
 23 23 | def f():
 
-F841_1.py:24:6: F841 Local variable `a` is assigned to but never used
+F841_1.py:24:6: F841 [*] Local variable `a` is assigned to but never used
    |
 23 | def f():
 24 |     (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
    |      ^ F841
    |
    = help: Remove assignment to unused variable `a`
 
-F841_1.py:24:9: F841 Local variable `b` is assigned to but never used
+ℹ Unsafe fix
+21 21 | 
+22 22 | 
+23 23 | def f():
+24    |-    (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
+   24 |+    (_a, b) = (x, y) = 1, 2  # this triggers F841 on everything
+
+F841_1.py:24:9: F841 [*] Local variable `b` is assigned to but never used
    |
 23 | def f():
 24 |     (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
    |         ^ F841
    |
    = help: Remove assignment to unused variable `b`
 
-F841_1.py:24:15: F841 Local variable `x` is assigned to but never used
+ℹ Unsafe fix
+21 21 | 
+22 22 | 
+23 23 | def f():
+24    |-    (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
+   24 |+    (a, _b) = (x, y) = 1, 2  # this triggers F841 on everything
+
+F841_1.py:24:15: F841 [*] Local variable `x` is assigned to but never used
    |
 23 | def f():
 24 |     (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
    |               ^ F841
    |
    = help: Remove assignment to unused variable `x`
 
-F841_1.py:24:18: F841 Local variable `y` is assigned to but never used
+ℹ Unsafe fix
+21 21 | 
+22 22 | 
+23 23 | def f():
+24    |-    (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
+   24 |+    (a, b) = (_x, y) = 1, 2  # this triggers F841 on everything
+
+F841_1.py:24:18: F841 [*] Local variable `y` is assigned to but never used
    |
 23 | def f():
 24 |     (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
    |                  ^ F841
    |
    = help: Remove assignment to unused variable `y`
 
+ℹ Unsafe fix
+21 21 | 
+22 22 | 
+23 23 | def f():
+24    |-    (a, b) = (x, y) = 1, 2  # this triggers F841 on everything
+   24 |+    (a, b) = (x, _y) = 1, 2  # this triggers F841 on everything
+
 

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__F841_F841_3.py.snap

@@ -156,7 +156,7 @@ F841_3.py:27:46: F841 [*] Local variable `z3` is assigned to but never used
 29 29 | 
 30 30 | 
 
-F841_3.py:32:6: F841 Local variable `x1` is assigned to but never used
+F841_3.py:32:6: F841 [*] Local variable `x1` is assigned to but never used
    |
 31 | def f():
 32 |     (x1, y1) = (1, 2)
@@ -166,7 +166,17 @@ F841_3.py:32:6: F841 Local variable `x1` is assigned to but never used
    |
    = help: Remove assignment to unused variable `x1`
 
-F841_3.py:32:10: F841 Local variable `y1` is assigned to but never used
+ℹ Unsafe fix
+29 29 | 
+30 30 | 
+31 31 | def f():
+32    |-    (x1, y1) = (1, 2)
+   32 |+    (_x1, y1) = (1, 2)
+33 33 |     (x2, y2) = coords2 = (1, 2)
+34 34 |     coords3 = (x3, y3) = (1, 2)
+35 35 | 
+
+F841_3.py:32:10: F841 [*] Local variable `y1` is assigned to but never used
    |
 31 | def f():
 32 |     (x1, y1) = (1, 2)
@@ -176,6 +186,16 @@ F841_3.py:32:10: F841 Local variable `y1` is assigned to but never used
    |
    = help: Remove assignment to unused variable `y1`
 
+ℹ Unsafe fix
+29 29 | 
+30 30 | 
+31 31 | def f():
+32    |-    (x1, y1) = (1, 2)
+   32 |+    (x1, _y1) = (1, 2)
+33 33 |     (x2, y2) = coords2 = (1, 2)
+34 34 |     coords3 = (x3, y3) = (1, 2)
+35 35 | 
+
 F841_3.py:33:16: F841 [*] Local variable `coords2` is assigned to but never used
    |
 31 | def f():

crates/ruff_linter/src/rules/pyflakes/snapshots/ruff_linter__rules__pyflakes__tests__preview__F841_F841_4.py.snap

@@ -20,7 +20,7 @@ F841_4.py:12:5: F841 [*] Local variable `a` is assigned to but never used
 14 14 | 
 15 15 | 
 
-F841_4.py:13:5: F841 Local variable `b` is assigned to but never used
+F841_4.py:13:5: F841 [*] Local variable `b` is assigned to but never used
    |
 11 | def bar():
 12 |     a = foo()
@@ -29,7 +29,17 @@ F841_4.py:13:5: F841 Local variable `b` is assigned to but never used
    |
    = help: Remove assignment to unused variable `b`
 
-F841_4.py:13:8: F841 Local variable `c` is assigned to but never used
+ℹ Unsafe fix
+10 10 | 
+11 11 | def bar():
+12 12 |     a = foo()
+13    |-    b, c = foo()
+   13 |+    _b, c = foo()
+14 14 | 
+15 15 | 
+16 16 | def baz():
+
+F841_4.py:13:8: F841 [*] Local variable `c` is assigned to but never used
    |
 11 | def bar():
 12 |     a = foo()
@@ -38,4 +48,14 @@ F841_4.py:13:8: F841 Local variable `c` is assigned to but never used
    |
    = help: Remove assignment to unused variable `c`
 
+ℹ Unsafe fix
+10 10 | 
+11 11 | def bar():
+12 12 |     a = foo()
+13    |-    b, c = foo()
+   13 |+    b, _c = foo()
+14 14 | 
+15 15 | 
+16 16 | def baz():
+