Summary

Fixes #21991

When a JSX && chain's final operand is a parenthesized JSX element with a leading own-line comment after ( (e.g. an inline // ... line comment, or a block comment separated from the JSX by a newline), oxfmt collapses the entire && chain onto a single line — even when the resulting line exceeds printWidth. Prettier breaks before each && so the line fits.

Input

export const A = () => (
  <div>
    {someLongConditionA &&
      someLongConditionB && ( // a much longer explanatory comment that clearly pushes the collapsed line beyond the 120 character print width
        <span>content</span>
      )}
  </div>
);

Before (incorrect — 163-char line at printWidth: 120)

export const A = () => (
  <div>
    {someLongConditionA && someLongConditionB && ( // a much longer explanatory comment that clearly pushes the collapsed line beyond the 120 character print width
      <span>content</span>
    )}
  </div>
);

After (matches Prettier)

export const A = () => (
  <div>
    {someLongConditionA &&
      someLongConditionB && ( // a much longer explanatory comment that clearly pushes the collapsed line beyond the 120 character print width
        <span>content</span>
      )}
  </div>
);

Root cause

In the binary-expression printer (binary_like_expression.rs), when the chain ends with a JSX operand, the chain is built as:

group(
  group(#logicalChain, [first, indent(tail_parts)]),
  indent_if_group_breaks(jsx_element, #logicalChain),
)

The #logicalChain group decides whether to break by running its own flat fits check on the chain operands. Leading comments on the JSX are emitted as line_suffix(comment) followed by expand_parent, but:

• line_suffix content is zero-width during flat-mode fits measurement, so the comment doesn't push the chain past printWidth.
• expand_parent only propagates to enclosing groups — and the #logicalChain group is a sibling of the comment (both are children of the outer wrapper), so its expand_parent never reaches the chain.

Result: the chain stays flat, the comment is queued for the end of the (now very long) line, and the printed line blows through printWidth.

Fix

Detect, when building the chain, whether the final JSX operand has a leading own-line comment via Comments::has_leading_own_line_comment. If so, mark the #logicalChain group with should_expand(true) so the chain breaks before each &&. This catches both inline // comments after ( (which always end the line) and block comments separated from the JSX by a newline.

A small helper BinaryLeftOrRightSide::operand_span_start returns the span start of the side's operand for the comment lookup.

Prettier conformance: no regressions (746/753 JS, 591/601 TS — unchanged).

AI Disclosure

This PR was co-authored with Claude Code (AI assistant), as noted in the commit. The fix was reviewed, tested against the full Prettier conformance suite, and verified to produce no regressions.