Fix bytearray repr escaping for apostrophes - #8316

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crates/vm/src/bytes_inner.rs (1)

231-255: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Conditionally escape the selected quote character.

The current implementation unconditionally escapes b'\'' even when " is chosen as the enclosing quote (which produces bytearray(b"\'")). Python's _Py_bytes_repr logic dynamically checks if a byte matches the chosen quote character, successfully avoiding escaping the single quote if double quotes are selected (producing bytearray(b"'")).

• crates/vm/src/bytes_inner.rs#L231-L255: Update the helper functions to accept the quote parameter and only escape ch if it matches quote (or b'\\').
• crates/vm/src/bytes_inner.rs#L279-L305: Pass quote as u8 when calling bytearray_repr_char_len and write_bytearray_repr_char.

🐛 Proposed fixes

crates/vm/src/bytes_inner.rs#L231-L255

-fn bytearray_repr_char_len(ch: u8) -> usize {
+fn bytearray_repr_char_len(ch: u8, quote: u8) -> usize {
     match ch {
-        b'\'' | b'\\' | b'\t' | b'\r' | b'\n' => 2,
+        b'\\' | b'\t' | b'\r' | b'\n' => 2,
+        c if c == quote => 2,
         0x20..=0x7e => 1,
         _ => 4, // \xHH
     }
 }

-fn write_bytearray_repr_char(ch: u8, buf: &mut String) {
+fn write_bytearray_repr_char(ch: u8, quote: u8, buf: &mut String) {
     match ch {
-        b'\'' => buf.push_str("\\'"),
         b'\\' => buf.push_str("\\\\"),
         b'\t' => buf.push_str("\\t"),
         b'\n' => buf.push_str("\\n"),
         b'\r' => buf.push_str("\\r"),
+        c if c == quote => {
+            buf.push('\\');
+            buf.push(c as char);
+        }
         0x20..=0x7e => buf.push(ch as char),
         ch => {

crates/vm/src/bytes_inner.rs#L279-L305

         let body_len = self
             .elements
             .iter()
             .try_fold(0usize, |len, &ch| {
-                len.checked_add(bytearray_repr_char_len(ch))
+                len.checked_add(bytearray_repr_char_len(ch, quote as u8))
             })
             .ok_or_else(|| Self::new_repr_overflow_error(vm))?;
         let len = class_name
             .len()
             .checked_add(DECORATION_LEN)
             .and_then(|len| len.checked_add(body_len))
             .ok_or_else(|| Self::new_repr_overflow_error(vm))?;
         let mut buf = String::with_capacity(len);
         buf.push_str(class_name);
         buf.push('(');
         buf.push('b');
         buf.push(quote);
         for &ch in &self.elements {
-            write_bytearray_repr_char(ch, &mut buf);
+            write_bytearray_repr_char(ch, quote as u8, &mut buf);
         }

Run the following script to verify CPython's behavior for bytearray representations when apostrophes are present:

#!/bin/bash
# Description: Check CPython's bytearray representations to verify conditional escaping.

python3 -c "print(repr(bytearray(b\"'\")))"
python3 -c "print(repr(bytearray(b'\"')))"
python3 -c "print(repr(bytearray(b\"'\\\"\")))"

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/vm/src/bytes_inner.rs` around lines 231 - 255, Update
bytearray_repr_char_len and write_bytearray_repr_char in
crates/vm/src/bytes_inner.rs:231-255 to accept the selected quote and escape it
only when ch matches that quote or is a backslash; update the callers in
crates/vm/src/bytes_inner.rs:279-305 to pass quote as u8 to both helpers.