Flag comparison-with-itself on builtin calls

crates/ruff/resources/test/fixtures/pylint/comparison_with_itself.py

@@ -19,6 +19,10 @@
 
 foo not in foo
 
+id(foo) == id(foo)
+
+len(foo) == len(foo)
+
 # Non-errors.
 "foo" == "foo"  # This is flagged by `comparison-of-constant` instead.
 
@@ -43,3 +47,11 @@
 foo in bar
 
 foo not in bar
+
+x(foo) == y(foo)
+
+id(foo) == id(bar)
+
+id(foo, bar) == id(foo, bar)
+
+id(foo, bar=1) == id(foo, bar=1)

crates/ruff/src/rules/pylint/rules/comparison_with_itself.rs

@@ -1,8 +1,8 @@
 use itertools::Itertools;
-use ruff_python_ast::{CmpOp, Expr, Ranged};
 
 use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::{CmpOp, Expr, Ranged};
 
 use crate::checkers::ast::Checker;
 use crate::rules::pylint::helpers::CmpOpExt;
@@ -51,17 +51,64 @@ pub(crate) fn comparison_with_itself(
         .tuple_windows()
         .zip(ops)
     {
-        if let (Expr::Name(left), Expr::Name(right)) = (left, right) {
-            if left.id == right.id {
+        match (left, right) {
+            // Ex) `foo == foo`
+            (Expr::Name(left_name), Expr::Name(right_name)) if left_name.id == right_name.id => {
                 checker.diagnostics.push(Diagnostic::new(
                     ComparisonWithItself {
-                        left: left.id.to_string(),
+                        left: checker.generator().expr(left),
                         op: *op,
-                        right: right.id.to_string(),
+                        right: checker.generator().expr(right),
                     },
-                    left.range(),
+                    left_name.range(),
                 ));
             }
+            // Ex) `id(foo) == id(foo)`
+            (Expr::Call(left_call), Expr::Call(right_call)) => {
+                // Both calls must take a single argument, of the same name.
+                if !left_call.arguments.keywords.is_empty()
+                    || !right_call.arguments.keywords.is_empty()
+                {
+                    continue;
+                }
+                let [Expr::Name(left_arg)] = left_call.arguments.args.as_slice() else {
+                    continue;
+                };
+                let [Expr::Name(right_right)] = right_call.arguments.args.as_slice() else {
+                    continue;
+                };
+                if left_arg.id != right_right.id {
+                    continue;
+                }
+
+                // Both calls must be to the same function.
+                let Expr::Name(left_func) = left_call.func.as_ref() else {
+                    continue;
+                };
+                let Expr::Name(right_func) = right_call.func.as_ref() else {
+                    continue;
+                };
+                if left_func.id != right_func.id {
+                    continue;
+                }
+
+                // The call must be to pure function, like `id`.
+                if matches!(
+                    left_func.id.as_str(),
+                    "id" | "len" | "type" | "int" | "bool" | "str" | "repr" | "bytes"
+                ) && checker.semantic().is_builtin(&left_func.id)
+                {
+                    checker.diagnostics.push(Diagnostic::new(
+                        ComparisonWithItself {
+                            left: checker.generator().expr(left),
+                            op: *op,
+                            right: checker.generator().expr(right),
+                        },
+                        left_call.range(),
+                    ));
+                }
+            }
+            _ => {}
         }
     }
 }

crates/ruff/src/rules/pylint/snapshots/ruff__rules__pylint__tests__PLR0124_comparison_with_itself.py.snap

@@ -97,7 +97,27 @@ comparison_with_itself.py:20:1: PLR0124 Name compared with itself, consider repl
 20 | foo not in foo
    | ^^^ PLR0124
 21 | 
-22 | # Non-errors.
+22 | id(foo) == id(foo)
+   |
+
+comparison_with_itself.py:22:1: PLR0124 Name compared with itself, consider replacing `id(foo) == id(foo)`
+   |
+20 | foo not in foo
+21 | 
+22 | id(foo) == id(foo)
+   | ^^^^^^^ PLR0124
+23 | 
+24 | len(foo) == len(foo)
+   |
+
+comparison_with_itself.py:24:1: PLR0124 Name compared with itself, consider replacing `len(foo) == len(foo)`
+   |
+22 | id(foo) == id(foo)
+23 | 
+24 | len(foo) == len(foo)
+   | ^^^^^^^^ PLR0124
+25 | 
+26 | # Non-errors.
    |