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Tweak comment placement for semicolons #544

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Merged
DavisVaughan merged 1 commit into from
Oct 22, 2026
Merged

Tweak comment placement for semicolons #544

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53 changes: 46 additions & 7 deletions crates/air_r_formatter/src/comments.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -152,16 +152,55 @@ fn handle_empty_statement_comment(

match comment.text_position() {
CommentTextPosition::EndOfLine => match (preceding, following) {
(Some(preceding), Some(following)) => {
// Is the comment on the same line as the closest non-empty `preceding` node?
let is_on_preceding_line = comment.preceding_node().is_some_and(|preceding| {
preceding
.siblings(Direction::Prev)
.take_while(|sibling| REmptyStatement::can_cast(sibling.kind()))
.all(|sibling| !sibling.has_leading_newline())
});

if is_on_preceding_line {
// ```r
// {
// 1; ; # Trails preceding
// 2
// }
// ```
CommentPlacement::trailing(preceding, comment)
} else {
// Leading keeps the relative ordering here:
//
// ```r
// {
// 1
// # Leads following 1
// ; # Leads following 2
// 2
// }
// ```
//
// And generally also makes sense here where the `;` is
// simply removed and the comment doesn't move
//
// ```r
// {
// 1
// ; # Leads following
// 2
// }
//
// ```
CommentPlacement::leading(following, comment)
}
}

// ```r
// {
// 1
// ; # Trails preceding
// 2
// 1; ; # Trails preceding
// }
// ```
(Some(preceding), Some(_)) => CommentPlacement::trailing(preceding, comment),

// ```r
//
// {
// 1
// ; # Trails preceding
Expand Down
148 changes: 145 additions & 3 deletions crates/air_r_formatter/src/r/auxiliary/empty_statement.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -527,6 +527,51 @@ mod test {
Ok(())
}

#[test]
fn test_comments_around_lone_semicolon_keep_order() -> anyhow::Result<()> {
let source = "\
{
1
# a
; # b
2
}";
let expected = "\
{
1
# a
# b
2
}
";
let tree = root([statement(braces(
token(L_CURLY, &[], "{", &[]),
[
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"1",
&[],
))),
empty(token(
SEMICOLON,
&[Newline, INDENT, Comment("# a"), Newline, INDENT],
";",
&[SPACE, Comment("# b")],
)),
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"2",
&[],
))),
],
token(R_CURLY, &[Newline], "}", &[]),
))]);
assert_eq!(format(tree, source)?, expected);
Ok(())
}

/// Handles every variant of [crate::comments::handle_empty_statement_comment]
#[test]
fn test_handle_empty_statement_comment() -> anyhow::Result<()> {
Expand All @@ -538,15 +583,77 @@ mod test {

let source = "\
{
1
; # Trails preceding
1; ; # Trails preceding
2
}";
let expected = "\
{
1 # Trails preceding
2
}
";
let tree = root([statement(braces(
token(L_CURLY, &[], "{", &[]),
[
statement_with_semicolon(
double(token(R_DOUBLE_LITERAL, &[Newline, INDENT], "1", &[])),
token(SEMICOLON, &[], ";", &[]),
),
empty(token(SEMICOLON, &[SPACE], ";", &[SPACE, TRAILS])),
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"2",
&[],
))),
],
token(R_CURLY, &[Newline], "}", &[]),
))]);
assert_eq!(format(tree, source)?, expected);

let source = "\
{
1; ; ; # Trails preceding
2
}";
let expected = "\
{
1 # Trails preceding
2
}
";
let tree = root([statement(braces(
token(L_CURLY, &[], "{", &[]),
[
statement_with_semicolon(
double(token(R_DOUBLE_LITERAL, &[Newline, INDENT], "1", &[])),
token(SEMICOLON, &[], ";", &[]),
),
empty(token(SEMICOLON, &[SPACE], ";", &[])),
empty(token(SEMICOLON, &[SPACE], ";", &[SPACE, TRAILS])),
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"2",
&[],
))),
],
token(R_CURLY, &[Newline], "}", &[]),
))]);
assert_eq!(format(tree, source)?, expected);

let source = "\
{
1
; ; # Leads following
2
}";
let expected = "\
{
1
# Leads following
2
}
";
let tree = root([statement(braces(
token(L_CURLY, &[], "{", &[]),
Expand All @@ -557,7 +664,42 @@ mod test {
"1",
&[],
))),
empty(token(SEMICOLON, &[Newline, INDENT], ";", &[SPACE, TRAILS])),
empty(token(SEMICOLON, &[Newline, INDENT], ";", &[])),
empty(token(SEMICOLON, &[SPACE], ";", &[SPACE, LEADS])),
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"2",
&[],
))),
],
token(R_CURLY, &[Newline], "}", &[]),
))]);
assert_eq!(format(tree, source)?, expected);

let source = "\
{
1
; # Leads following
2
}";
let expected = "\
{
1
# Leads following
2
}
";
let tree = root([statement(braces(
token(L_CURLY, &[], "{", &[]),
[
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
"1",
&[],
))),
empty(token(SEMICOLON, &[Newline, INDENT], ";", &[SPACE, LEADS])),
statement(double(token(
R_DOUBLE_LITERAL,
&[Newline, INDENT],
Expand Down
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