[refurb] Mark the FURB161 fix unsafe except for integers and booleans

crates/ruff_linter/resources/test/fixtures/refurb/FURB161.py

@@ -12,6 +12,7 @@ def ten() -> int:
 count = bin(ten()).count("1")  # FURB161
 count = bin((10)).count("1")  # FURB161
 count = bin("10" "15").count("1")  # FURB161
+count = bin("123").count("1") # FURB161
 
 count = x.bit_count()  # OK
 count = (10).bit_count()  # OK

crates/ruff_linter/src/rules/refurb/rules/bit_count.rs

@@ -1,7 +1,8 @@
-use ruff_diagnostics::{AlwaysFixableViolation, Diagnostic, Edit, Fix};
+use ruff_diagnostics::{AlwaysFixableViolation, Applicability, Diagnostic, Edit, Fix};
 use ruff_macros::{derive_message_formats, ViolationMetadata};
 use ruff_python_ast::PythonVersion;
 use ruff_python_ast::{self as ast, Expr, ExprAttribute, ExprCall};
+use ruff_python_semantic::analyze::type_inference::{NumberLike, PythonType, ResolvedPythonType};
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
@@ -27,6 +28,11 @@ use crate::fix::snippet::SourceCodeSnippet;
 /// y = 0b1111011.bit_count()
 /// ```
 ///
+/// ## Fix safety
+/// This rule's fix is marked as unsafe unless the argument to `bin` can be inferred as
+/// an instance of a type that implements the `__index__` and `bit_count` methods because this can
+/// change the exception raised at runtime for an invalid argument.
+///
 /// ## Options
 /// - `target-version`
 ///
@@ -163,6 +169,14 @@ pub(crate) fn bit_count(checker: &Checker, call: &ExprCall) {
         | Expr::Subscript(_) => false,
     };
 
+    // check if the fix is safe or not
+    let applicability: Applicability = match ResolvedPythonType::from(arg) {
+        ResolvedPythonType::Atom(PythonType::Number(NumberLike::Integer | NumberLike::Bool)) => {
+            Applicability::Safe
+        }
+        _ => Applicability::Unsafe,
+    };
+
     let replacement = if parenthesize {
         format!("({literal_text}).bit_count()")
     } else {
@@ -176,11 +190,10 @@ pub(crate) fn bit_count(checker: &Checker, call: &ExprCall) {
         },
         call.range(),
     );
-
-    diagnostic.set_fix(Fix::safe_edit(Edit::range_replacement(
-        replacement,
-        call.range(),
-    )));
+    diagnostic.set_fix(Fix::applicable_edit(
+        Edit::range_replacement(replacement, call.range()),
+        applicability,
+    ));
 
     checker.report_diagnostic(diagnostic);
 }

crates/ruff_linter/src/rules/refurb/snapshots/ruff_linter__rules__refurb__tests__FURB161_FURB161.py.snap

@@ -12,7 +12,7 @@ FURB161.py:6:9: FURB161 [*] Use of `bin(x).count('1')`
   |
   = help: Replace with `(x).bit_count()`
 
-ℹ Safe fix
+ℹ Unsafe fix
 3 3 | def ten() -> int:
 4 4 |     return 10
 5 5 | 
@@ -137,15 +137,15 @@ FURB161.py:12:9: FURB161 [*] Use of `bin(ten()).count('1')`
    |
    = help: Replace with `ten().bit_count()`
 
-ℹ Safe fix
+ℹ Unsafe fix
 9  9  | count = bin(0xA).count("1")  # FURB161
 10 10 | count = bin(0o12).count("1")  # FURB161
 11 11 | count = bin(0x10 + 0x1000).count("1")  # FURB161
 12    |-count = bin(ten()).count("1")  # FURB161
    12 |+count = ten().bit_count()  # FURB161
 13 13 | count = bin((10)).count("1")  # FURB161
 14 14 | count = bin("10" "15").count("1")  # FURB161
-15 15 | 
+15 15 | count = bin("123").count("1") # FURB161
 
 FURB161.py:13:9: FURB161 [*] Use of `bin(10).count('1')`
    |
@@ -154,6 +154,7 @@ FURB161.py:13:9: FURB161 [*] Use of `bin(10).count('1')`
 13 | count = bin((10)).count("1")  # FURB161
    |         ^^^^^^^^^^^^^^^^^^^^ FURB161
 14 | count = bin("10" "15").count("1")  # FURB161
+15 | count = bin("123").count("1") # FURB161
    |
    = help: Replace with `(10).bit_count()`
 
@@ -164,26 +165,46 @@ FURB161.py:13:9: FURB161 [*] Use of `bin(10).count('1')`
 13    |-count = bin((10)).count("1")  # FURB161
    13 |+count = (10).bit_count()  # FURB161
 14 14 | count = bin("10" "15").count("1")  # FURB161
-15 15 | 
-16 16 | count = x.bit_count()  # OK
+15 15 | count = bin("123").count("1") # FURB161
+16 16 | 
 
 FURB161.py:14:9: FURB161 [*] Use of `bin("10" "15").count('1')`
    |
 12 | count = bin(ten()).count("1")  # FURB161
 13 | count = bin((10)).count("1")  # FURB161
 14 | count = bin("10" "15").count("1")  # FURB161
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ FURB161
-15 |
-16 | count = x.bit_count()  # OK
+15 | count = bin("123").count("1") # FURB161
    |
    = help: Replace with `("10" "15").bit_count()`
 
-ℹ Safe fix
+ℹ Unsafe fix
 11 11 | count = bin(0x10 + 0x1000).count("1")  # FURB161
 12 12 | count = bin(ten()).count("1")  # FURB161
 13 13 | count = bin((10)).count("1")  # FURB161
 14    |-count = bin("10" "15").count("1")  # FURB161
    14 |+count = ("10" "15").bit_count()  # FURB161
-15 15 | 
-16 16 | count = x.bit_count()  # OK
-17 17 | count = (10).bit_count()  # OK
+15 15 | count = bin("123").count("1") # FURB161
+16 16 | 
+17 17 | count = x.bit_count()  # OK
+
+FURB161.py:15:9: FURB161 [*] Use of `bin("123").count('1')`
+   |
+13 | count = bin((10)).count("1")  # FURB161
+14 | count = bin("10" "15").count("1")  # FURB161
+15 | count = bin("123").count("1") # FURB161
+   |         ^^^^^^^^^^^^^^^^^^^^^ FURB161
+16 |
+17 | count = x.bit_count()  # OK
+   |
+   = help: Replace with `"123".bit_count()`
+
+ℹ Unsafe fix
+12 12 | count = bin(ten()).count("1")  # FURB161
+13 13 | count = bin((10)).count("1")  # FURB161
+14 14 | count = bin("10" "15").count("1")  # FURB161
+15    |-count = bin("123").count("1") # FURB161
+   15 |+count = "123".bit_count() # FURB161
+16 16 | 
+17 17 | count = x.bit_count()  # OK
+18 18 | count = (10).bit_count()  # OK