specialize ConversionFlag

ast/asdl_rs.py

@@ -28,6 +28,7 @@
 BUILTIN_INT_NAMES = {
     "simple": "bool",
     "is_async": "bool",
+    "conversion": "ConversionFlag",
 }
 
 RUST_KEYWORDS = {

ast/src/fold_helpers.rs

@@ -1,4 +1,4 @@
-use crate::{builtin, fold::Fold};
+use crate::{builtin, fold::Fold, ConversionFlag};
 
 pub trait Foldable<T, U> {
     type Mapped;
@@ -67,5 +67,6 @@ simple_fold!(
     builtin::String,
     builtin::Identifier,
     bool,
+    ConversionFlag,
     builtin::Constant
 );

ast/src/gen/generic.rs

@@ -931,7 +931,7 @@ impl<R> From<ExprCall<R>> for Expr<R> {
 pub struct ExprFormattedValue<R = TextRange> {
     pub range: R,
     pub value: Box<Expr<R>>,
-    pub conversion: Int,
+    pub conversion: ConversionFlag,
     pub format_spec: Option<Box<Expr<R>>>,
 }
 

ast/src/generic.rs

@@ -1,5 +1,5 @@
 #![allow(clippy::derive_partial_eq_without_eq)]
-pub use crate::{builtin::*, text_size::TextSize, Node};
+pub use crate::{builtin::*, text_size::TextSize, ConversionFlag, Node};
 use std::fmt::{Debug, Display, Formatter};
 use std::marker::PhantomData;
 

ast/src/pyo3.rs

@@ -1,4 +1,4 @@
-use crate::{source_code::SourceRange, text_size::TextRange, Node};
+use crate::{source_code::SourceRange, text_size::TextRange, ConversionFlag, Node};
 use num_complex::Complex64;
 use once_cell::sync::OnceCell;
 use pyo3::prelude::*;
@@ -73,6 +73,13 @@ impl ToPyo3Ast for bool {
     }
 }
 
+impl ToPyo3Ast for ConversionFlag {
+    #[inline]
+    fn to_pyo3_ast(&self, py: Python) -> PyResult<Py<PyAny>> {
+        Ok((*self as i8).to_object(py))
+    }
+}
+
 impl ToPyo3Ast for crate::Constant {
     #[inline]
     fn to_pyo3_ast(&self, py: Python) -> PyResult<Py<PyAny>> {

ast/src/unparse.rs

@@ -346,7 +346,7 @@ impl<'a> Unparser<'a> {
                 conversion,
                 format_spec,
                 range: _range,
-            }) => self.unparse_formatted(value, conversion.to_u32(), format_spec.as_deref())?,
+            }) => self.unparse_formatted(value, *conversion, format_spec.as_deref())?,
             Expr::JoinedStr(crate::ExprJoinedStr {
                 values,
                 range: _range,
@@ -519,7 +519,7 @@ impl<'a> Unparser<'a> {
     fn unparse_formatted<U>(
         &mut self,
         val: &Expr<U>,
-        conversion: u32,
+        conversion: ConversionFlag,
         spec: Option<&Expr<U>>,
     ) -> fmt::Result {
         let buffered = to_string_fmt(|f| Unparser::new(f).unparse_expr(val, precedence::TEST + 1));
@@ -533,7 +533,7 @@ impl<'a> Unparser<'a> {
         self.p(&buffered)?;
         drop(buffered);
 
-        if conversion != ConversionFlag::None as u32 {
+        if conversion != ConversionFlag::None {
             self.p("!")?;
             let buf = &[conversion as u8];
             let c = std::str::from_utf8(buf).unwrap();
@@ -568,7 +568,7 @@ impl<'a> Unparser<'a> {
                 conversion,
                 format_spec,
                 range: _range,
-            }) => self.unparse_formatted(value, conversion.to_u32(), format_spec.as_deref()),
+            }) => self.unparse_formatted(value, *conversion, format_spec.as_deref()),
             _ => unreachable!(),
         }
     }

core/Cargo.toml

@@ -13,6 +13,7 @@ ruff_text_size = { path = "../ruff_text_size" }
 ruff_source_location = { path = "../ruff_source_location", optional = true }
 
 serde = { version = "1.0.133", optional = true, default-features = false, features = ["derive"] }
+is-macro.workspace = true
 
 [features]
 default = []

core/src/format.rs

@@ -1,13 +1,13 @@
 /// Transforms a value prior to formatting it.
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-#[repr(u8)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, is_macro::Is)]
+#[repr(i8)]
 pub enum ConversionFlag {
     /// No conversion
-    None = 0, // CPython uses -1 but not pleasure for us
+    None = -1, // CPython uses -1
     /// Converts by calling `str(<value>)`.
-    Str = b's',
+    Str = b's' as i8,
     /// Converts by calling `ascii(<value>)`.
-    Ascii = b'a',
+    Ascii = b'a' as i8,
     /// Converts by calling `repr(<value>)`.
-    Repr = b'r',
+    Repr = b'r' as i8,
 }