Skip to content

fix(formatter): print comments before fat arrow as-is for ArrowFunctionExpression #15050

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
graphite-app merged 1 commit into from
Oct 29, 2025
Merged

fix(formatter): print comments before fat arrow as-is for ArrowFunctionExpression #15050

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
85 changes: 46 additions & 39 deletions crates/oxc_formatter/src/write/arrow_function_expression.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,10 @@ use crate::{
Buffer, Comments, Format, FormatError, FormatResult, Formatter, SourceText,
buffer::RemoveSoftLinesBuffer,
prelude::*,
trivia::{FormatLeadingComments, format_trailing_comments},
trivia::{
DanglingIndentMode, FormatDanglingComments, FormatLeadingComments,
FormatTrailingComments, format_trailing_comments,
},
},
options::FormatTrailingCommas,
utils::{assignment_like::AssignmentLikeLayout, expression::ExpressionLeftSide},
Expand Down Expand Up @@ -502,34 +505,46 @@ impl<'a> Format<'a> for ArrowChain<'a, '_> {
let is_first = is_first_in_chain;

let formatted_signature = format_with(|f| {
if should_format_comments {
// A grouped layout implies that the arrow chain is trying to be rendered
// in a condensed, single-line format (at least the signatures, not
// necessarily the body). In that case, we _need_ to prevent the leading
// comments from inserting line breaks. But if it's _not_ a grouped layout,
// then we want to _force_ the line break so that the leading comments
// don't inadvertently end up on the previous line after the fat arrow.
if is_grouped_call_arg_layout {
write!(f, [space(), format_leading_comments(arrow.span())])?;
let format_leading_comments = format_once(|f| {
if should_format_comments {
// A grouped layout implies that the arrow chain is trying to be rendered
// in a condensed, single-line format (at least the signatures, not
// necessarily the body). In that case, we _need_ to prevent the leading
// comments from inserting line breaks. But if it's _not_ a grouped layout,
// then we want to _force_ the line break so that the leading comments
// don't inadvertently end up on the previous line after the fat arrow.
if is_grouped_call_arg_layout {
write!(f, [space(), format_leading_comments(arrow.span())])
} else {
write!(
f,
[
soft_line_break_or_space(),
format_leading_comments(arrow.span())
]
)
}
} else {
write!(
f,
[
soft_line_break_or_space(),
format_leading_comments(arrow.span())
]
)?;
Ok(())
}
}
});

let start = arrow.span().start;
write!(
f,
[format_signature(
arrow,
is_grouped_call_arg_layout,
is_first,
self.options.cache_mode
)]
[
FormatContentWithCacheMode::new(
Span::new(start, start),
format_leading_comments,
self.options.cache_mode,
),
format_signature(
arrow,
is_grouped_call_arg_layout,
is_first,
self.options.cache_mode
)
]
)
});

Expand Down Expand Up @@ -559,7 +574,7 @@ impl<'a> Format<'a> for ArrowChain<'a, '_> {
Ok(())
});

write!(f, [group(&join_signatures).should_expand(*expand_signatures)])
group(&join_signatures).should_expand(*expand_signatures).fmt(f)
});

let format_tail_body_inner = format_with(|f| {
Expand Down Expand Up @@ -607,14 +622,6 @@ impl<'a> Format<'a> for ArrowChain<'a, '_> {
write!(f, [format_tail_body])?;
}
}

// Format the trailing comments of all arrow function EXCEPT the first one because
// the comments of the head get formatted as part of the `FormatJsArrowFunctionExpression` call.
// TODO: It seems unneeded in the current oxc implementation?
// for arrow in self.arrows().skip(1) {
// write!(f, format_trailing_comments(arrow.span().end))?;
// }

Ok(())
});

Expand Down Expand Up @@ -758,12 +765,12 @@ fn format_signature<'a, 'b>(
)?;
}

// TODO: for case `a = (x: any): x is string /* comment */ => {}`
// if f.comments().has_dangling_comments(arrow.span()) {
// write!(f, [space(), format_dangling_comments(arrow.span())])?;
// }

Ok(())
// Print comments before the fat arrow (`=>`)
let comments_before_fat_arrow =
f.context().comments().comments_before_character(arrow.params.span().end, b'=');
let content =
format_once(|f| FormatTrailingComments::Comments(comments_before_fat_arrow).fmt(f));
write!(f, [FormatContentWithCacheMode::new(arrow.span, content, cache_mode)])
})
}

Expand Down
22 changes: 21 additions & 1 deletion crates/oxc_formatter/tests/fixtures/js/comments/arrow.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,4 +4,24 @@

() =>
// comment
({})
({});

() /* comment1 */ => /* comment2 */ { };

() /**/ => //
() /**/ => /**/
() /**/ => /**/ {
//
}

call(
() /* comment1 */ => /* comment2 */ { }
);

call(
() /**/ => //
() /**/ => /**/
() /**/ => /**/ {
//
}
);
42 changes: 41 additions & 1 deletion crates/oxc_formatter/tests/fixtures/js/comments/arrow.js.snap
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,27 @@ source: crates/oxc_formatter/tests/fixtures/mod.rs

() =>
// comment
({})
({});

() /* comment1 */ => /* comment2 */ { };

() /**/ => //
() /**/ => /**/
() /**/ => /**/ {
//
}

call(
() /* comment1 */ => /* comment2 */ { }
);

call(
() /**/ => //
() /**/ => /**/
() /**/ => /**/ {
//
}
);

==================== Output ====================
() =>
Expand All @@ -19,4 +39,24 @@ source: crates/oxc_formatter/tests/fixtures/mod.rs
// comment
({});

() /* comment1 */ => /* comment2 */ {};

() /**/ =>
//
() /**/ =>
/**/
() /**/ => /**/ {
//
};

call(() /* comment1 */ => /* comment2 */ {});

call(() /**/ =>
//
() /**/ =>
/**/
() /**/ => /**/ {
//
});

===================== End =====================
Loading