[ruff] Implement check for Decimal called with a float literal (RUF032)

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

@@ -1011,8 +1011,8 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
             if checker.enabled(Rule::UnnecessaryIterableAllocationForFirstElement) {
                 ruff::rules::unnecessary_iterable_allocation_for_first_element(checker, expr);
             }
-            if checker.enabled(Rule::FloatLiteralDecimal) {
-                ruff::rules::float_literal_decimal_syntax(checker, call);
+            if checker.enabled(Rule::DecimalFromFloatLiteral) {
+                ruff::rules::decimal_from_float_literal_syntax(checker, call);
             }
             if checker.enabled(Rule::IntOnSlicedStr) {
                 refurb::rules::int_on_sliced_str(checker, call);

crates/ruff_linter/src/codes.rs

@@ -958,7 +958,7 @@ pub fn code_to_rule(linter: Linter, code: &str) -> Option<(RuleGroup, Rule)> {
         (Ruff, "029") => (RuleGroup::Preview, rules::ruff::rules::UnusedAsync),
         (Ruff, "030") => (RuleGroup::Preview, rules::ruff::rules::AssertWithPrintMessage),
         (Ruff, "031") => (RuleGroup::Preview, rules::ruff::rules::IncorrectlyParenthesizedTupleInSubscript),
-        (Ruff, "032") => (RuleGroup::Preview, rules::ruff::rules::FloatLiteralDecimal),
+        (Ruff, "032") => (RuleGroup::Preview, rules::ruff::rules::DecimalFromFloatLiteral),
         (Ruff, "100") => (RuleGroup::Stable, rules::ruff::rules::UnusedNOQA),
         (Ruff, "101") => (RuleGroup::Stable, rules::ruff::rules::RedirectedNOQA),
 

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

@@ -57,7 +57,7 @@ mod tests {
     #[test_case(Rule::UnusedAsync, Path::new("RUF029.py"))]
     #[test_case(Rule::AssertWithPrintMessage, Path::new("RUF030.py"))]
     #[test_case(Rule::IncorrectlyParenthesizedTupleInSubscript, Path::new("RUF031.py"))]
-    #[test_case(Rule::FloatLiteralDecimal, Path::new("RUF032.py"))]
+    #[test_case(Rule::DecimalFromFloatLiteral, Path::new("RUF032.py"))]
     #[test_case(Rule::RedirectedNOQA, Path::new("RUF101.py"))]
     fn rules(rule_code: Rule, path: &Path) -> Result<()> {
         let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());

crates/ruff_linter/src/rules/ruff/rules/float_literal_decimal.rs → crates/ruff_linter/src/rules/ruff/rules/decimal_from_float_literal.rs

@@ -9,7 +9,7 @@ use crate::checkers::ast::Checker;
 /// Checks for `Decimal` calls passing a float literal.
 ///
 /// ## Why is this bad?
-/// Float literals are non-deterministic and can lead to unexpected results. The `Decimal` class is designed to handle
+/// Float literals have limited precision that can lead to unexpected results. The `Decimal` class is designed to handle
 /// numbers with fixed-point precision, so a string literal should be used instead.
 ///
 /// ## Example
@@ -21,11 +21,15 @@ use crate::checkers::ast::Checker;
 /// Use instead:
 /// ```python
 /// num = Decimal("1.2345")
+///
+/// ## Fix Safety
+/// This rule's fix is marked as unsafe because it changes the underlying value of the `Decimal` instance that is
+/// constructed. This can lead to unexpected behavior if your program relies on the previous imprecise value.
 /// ```
 #[violation]
-pub struct FloatLiteralDecimal;
+pub struct DecimalFromFloatLiteral;
 
-impl AlwaysFixableViolation for FloatLiteralDecimal {
+impl AlwaysFixableViolation for DecimalFromFloatLiteral {
     #[derive_message_formats]
     fn message(&self) -> String {
         format!(r#"`Decimal()` called with float literal argument"#)
@@ -37,35 +41,38 @@ impl AlwaysFixableViolation for FloatLiteralDecimal {
 }
 
 /// RUF032: `Decimal()` called with float literal argument
-pub(crate) fn float_literal_decimal_syntax(checker: &mut Checker, call: &ast::ExprCall) {
+pub(crate) fn decimal_from_float_literal_syntax(checker: &mut Checker, call: &ast::ExprCall) {
+    let Some(arg) = call.arguments.args.first() else {
+        return;
+    };
+
     if !checker
         .semantic()
         .resolve_qualified_name(call.func.as_ref())
         .is_some_and(|qualified_name| matches!(qualified_name.segments(), ["decimal", "Decimal"]))
     {
         return;
     }
-    if let Some(arg) = call.arguments.args.first() {
+
+    if let ast::Expr::NumberLiteral(ast::ExprNumberLiteral {
+        value: ast::Number::Float(_),
+        ..
+    }) = arg
+    {
+        let diagnostic = Diagnostic::new(DecimalFromFloatLiteral, arg.range()).with_fix(
+            fix_float_literal(arg.range(), &checker.generator().expr(arg)),
+        );
+        checker.diagnostics.push(diagnostic);
+    } else if let ast::Expr::UnaryOp(ast::ExprUnaryOp { operand, .. }) = arg {
         if let ast::Expr::NumberLiteral(ast::ExprNumberLiteral {
             value: ast::Number::Float(_),
             ..
-        }) = arg
+        }) = operand.as_ref()
         {
-            let diagnostic = Diagnostic::new(FloatLiteralDecimal, arg.range()).with_fix(
+            let diagnostic = Diagnostic::new(DecimalFromFloatLiteral, arg.range()).with_fix(
                 fix_float_literal(arg.range(), &checker.generator().expr(arg)),
             );
             checker.diagnostics.push(diagnostic);
-        } else if let ast::Expr::UnaryOp(ast::ExprUnaryOp { operand, .. }) = arg {
-            if let ast::Expr::NumberLiteral(ast::ExprNumberLiteral {
-                value: ast::Number::Float(_),
-                ..
-            }) = operand.as_ref()
-            {
-                let diagnostic = Diagnostic::new(FloatLiteralDecimal, arg.range()).with_fix(
-                    fix_float_literal(arg.range(), &checker.generator().expr(arg)),
-                );
-                checker.diagnostics.push(diagnostic);
-            }
         }
     }
 }

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

@@ -3,9 +3,9 @@ pub(crate) use assert_with_print_message::*;
 pub(crate) use assignment_in_assert::*;
 pub(crate) use asyncio_dangling_task::*;
 pub(crate) use collection_literal_concatenation::*;
+pub(crate) use decimal_from_float_literal::*;
 pub(crate) use default_factory_kwarg::*;
 pub(crate) use explicit_f_string_type_conversion::*;
-pub(crate) use float_literal_decimal::*;
 pub(crate) use function_call_in_dataclass_default::*;
 pub(crate) use implicit_optional::*;
 pub(crate) use incorrectly_parenthesized_tuple_in_subscript::*;
@@ -37,9 +37,9 @@ mod assignment_in_assert;
 mod asyncio_dangling_task;
 mod collection_literal_concatenation;
 mod confusables;
+mod decimal_from_float_literal;
 mod default_factory_kwarg;
 mod explicit_f_string_type_conversion;
-mod float_literal_decimal;
 mod function_call_in_dataclass_default;
 mod helpers;
 mod implicit_optional;