[pylint] Implement potential-index-error (PLE0643)

crates/ruff_linter/resources/test/fixtures/pylint/potential_index_error.py

@@ -0,0 +1,9 @@
+print([1, 2, 3][3])  # PLE0643
+print([1, 2, 3][-4])  # PLE0643
+print([1, 2, 3][999999999999999999999999999999999999999999])  # PLE0643
+print([1, 2, 3][-999999999999999999999999999999999999999999])  # PLE0643
+
+print([1, 2, 3][2])  # OK
+print([1, 2, 3][0])  # OK
+print([1, 2, 3][-3])  # OK
+print([1, 2, 3][3:])  # OK

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

@@ -125,6 +125,9 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
             if checker.enabled(Rule::SliceCopy) {
                 refurb::rules::slice_copy(checker, subscript);
             }
+            if checker.enabled(Rule::PotentialIndexError) {
+                pylint::rules::potential_index_error(checker, value, slice);
+            }
 
             pandas_vet::rules::subscript(checker, value, expr);
         }

crates/ruff_linter/src/codes.rs

@@ -229,6 +229,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Pylint, "E0307") => (RuleGroup::Stable, rules::pylint::rules::InvalidStrReturnType),
         (Pylint, "E0604") => (RuleGroup::Stable, rules::pylint::rules::InvalidAllObject),
         (Pylint, "E0605") => (RuleGroup::Stable, rules::pylint::rules::InvalidAllFormat),
+        (Pylint, "E0643") => (RuleGroup::Preview, rules::pylint::rules::PotentialIndexError),
         (Pylint, "E0704") => (RuleGroup::Preview, rules::pylint::rules::MisplacedBareRaise),
         (Pylint, "E1132") => (RuleGroup::Preview, rules::pylint::rules::RepeatedKeywordArgument),
         (Pylint, "E1142") => (RuleGroup::Stable, rules::pylint::rules::AwaitOutsideAsync),

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

@@ -167,6 +167,7 @@ mod tests {
     #[test_case(Rule::NoClassmethodDecorator, Path::new("no_method_decorator.py"))]
     #[test_case(Rule::UnnecessaryDunderCall, Path::new("unnecessary_dunder_call.py"))]
     #[test_case(Rule::NoStaticmethodDecorator, Path::new("no_method_decorator.py"))]
+    #[test_case(Rule::PotentialIndexError, Path::new("potential_index_error.py"))]
     #[test_case(Rule::SuperWithoutBrackets, Path::new("super_without_brackets.py"))]
     #[test_case(
         Rule::UnnecessaryDictIndexLookup,

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

@@ -42,6 +42,7 @@ pub(crate) use no_self_use::*;
 pub(crate) use non_ascii_module_import::*;
 pub(crate) use non_ascii_name::*;
 pub(crate) use nonlocal_without_binding::*;
+pub(crate) use potential_index_error::*;
 pub(crate) use property_with_parameters::*;
 pub(crate) use redefined_argument_from_local::*;
 pub(crate) use redefined_loop_name::*;
@@ -124,6 +125,7 @@ mod no_self_use;
 mod non_ascii_module_import;
 mod non_ascii_name;
 mod nonlocal_without_binding;
+mod potential_index_error;
 mod property_with_parameters;
 mod redefined_argument_from_local;
 mod redefined_loop_name;

crates/ruff_linter/src/rules/pylint/rules/potential_index_error.rs

@@ -0,0 +1,80 @@
+use std::str::FromStr;
+
+use ruff_python_ast::{self as ast, Expr};
+
+use ruff_diagnostics::{Diagnostic, Violation};
+use ruff_macros::{derive_message_formats, violation};
+
+use crate::checkers::ast::Checker;
+
+/// ## What it does
+/// Checks for potential hard-coded IndexErrors, which occurs when accessing
+/// a list or tuple with an index that is known to be out of bounds.
+///
+/// ## Why is this bad?
+/// This will cause a runtime error.
+///
+/// ## Example
+/// ```python
+/// print([1, 2, 3][123])
+/// ```
+///
+#[violation]
+pub struct PotentialIndexError;
+
+impl Violation for PotentialIndexError {
+    #[derive_message_formats]
+    fn message(&self) -> String {
+        format!("Potential IndexError")
+    }
+}
+
+/// PLE0643
+pub(crate) fn potential_index_error(checker: &mut Checker, value: &Expr, slice: &Expr) {
+    let length = match value {
+        Expr::Tuple(ast::ExprTuple { elts, .. }) | Expr::List(ast::ExprList { elts, .. }) => {
+            match i64::try_from(elts.len()) {
+                Ok(length) => length,
+                Err(_) => return,
+            }
+        }
+        _ => {
+            return;
+        }
+    };
+
+    let (number_value, range) = match slice {
+        Expr::NumberLiteral(ast::ExprNumberLiteral {
+            value: ast::Number::Int(number_value),
+            range,
+        }) => (number_value.to_owned(), *range),
+        Expr::UnaryOp(ast::ExprUnaryOp {
+            op: ast::UnaryOp::USub,
+            operand,
+            range,
+        }) => match operand.as_ref() {
+            Expr::NumberLiteral(ast::ExprNumberLiteral {
+                value: ast::Number::Int(number_value),
+                ..
+            }) => (
+                ast::Int::from_str(&format!("-{number_value}")).unwrap(),
+                *range,
+            ),
+            _ => return,
+        },
+        _ => return,
+    };
+
+    let emit = if let Some(number) = number_value.as_i64() {
+        number >= length || number < -length
+    } else {
+        // this should be impossible
+        true
+    };
+
+    if emit {
+        checker
+            .diagnostics
+            .push(Diagnostic::new(PotentialIndexError, range));
+    }
+}

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLE0643_potential_index_error.py.snap

@@ -0,0 +1,40 @@
+---
+source: crates/ruff_linter/src/rules/pylint/mod.rs
+---
+potential_index_error.py:1:17: PLE0643 Potential IndexError
+  |
+1 | print([1, 2, 3][3])  # PLE0643
+  |                 ^ PLE0643
+2 | print([1, 2, 3][-4])  # PLE0643
+3 | print([1, 2, 3][999999999999999999999999999999999999999999])  # PLE0643
+  |
+
+potential_index_error.py:2:17: PLE0643 Potential IndexError
+  |
+1 | print([1, 2, 3][3])  # PLE0643
+2 | print([1, 2, 3][-4])  # PLE0643
+  |                 ^^ PLE0643
+3 | print([1, 2, 3][999999999999999999999999999999999999999999])  # PLE0643
+4 | print([1, 2, 3][-999999999999999999999999999999999999999999])  # PLE0643
+  |
+
+potential_index_error.py:3:17: PLE0643 Potential IndexError
+  |
+1 | print([1, 2, 3][3])  # PLE0643
+2 | print([1, 2, 3][-4])  # PLE0643
+3 | print([1, 2, 3][999999999999999999999999999999999999999999])  # PLE0643
+  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PLE0643
+4 | print([1, 2, 3][-999999999999999999999999999999999999999999])  # PLE0643
+  |
+
+potential_index_error.py:4:17: PLE0643 Potential IndexError
+  |
+2 | print([1, 2, 3][-4])  # PLE0643
+3 | print([1, 2, 3][999999999999999999999999999999999999999999])  # PLE0643
+4 | print([1, 2, 3][-999999999999999999999999999999999999999999])  # PLE0643
+  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ PLE0643
+5 | 
+6 | print([1, 2, 3][2])  # OK
+  |
+
+