extra spacing added to normalised inner comment in a function call

[topecongiro]

E.g.

foo(xxxxxxx, xxxxxxxx /* inline comment */, y /* sup */);

foo(
    xxxxxxx,
    xxxxxxxx, // inline comment
    y, /* sup */
);

when normalize_comments = true.

[scampi]

Do you have a working example @topecongiro ?
The one from the description gets normalised:

 fn bar() {
-    foo(xxxxxxx, xxxxxxxx /* inline comment */, y /* sup */);
+    foo(
+        xxxxxxx, xxxxxxxx, // inline comment
+        y,        // sup
+    );
 }

[scampi]

Although the spacing before // sup is strange...

[topecongiro]

Yeah looks like the original issue is fixed.

[scampi]

@topecongiro I have renamed the issue to better reflect the new problem

[ytmimi]

This is still reproducible with the current masterrustfmt 1.5.1-nightly (0cb294f0 2022-07-12) when setting normailze_comments=true

input

fn main() {
    foo(xxxxxxx, xxxxxxxx /* inline comment */, y /* sup */);
}

output

fn main() {
    foo(
        xxxxxxx, xxxxxxxx, // inline comment
        y,        // sup
    );
}

Doing some testing, and forcing try_overflow_last_item last item to return a DefinitiveListTactic::Vertical produces the following output:

fn main() {
    foo(
        xxxxxxx,
        xxxxxxxx, // inline comment
        y,        // sup
    );
}

Just a hunch but it seems like the comment alignment is still trying to align the comments even when the tactic = DefinitiveListTactic::Mixed, so I'm guessing the issue occurs somewhere when handling post comments in write_list.

rustfmt/src/lists.rs

Lines 404 to 504 in a7bf009

	// Post-comments
	if tactic == DefinitiveListTactic::Horizontal && item.post_comment.is_some() {
	let comment = item.post_comment.as_ref().unwrap();
	let formatted_comment = rewrite_comment(
	comment,
	true,
	Shape::legacy(formatting.shape.width, Indent::empty()),
	formatting.config,
	)?;
	result.push(' ');
	result.push_str(&formatted_comment);
	}
	if separate && sep_place.is_back() {
	result.push_str(formatting.separator);
	}
	if tactic != DefinitiveListTactic::Horizontal && item.post_comment.is_some() {
	let comment = item.post_comment.as_ref().unwrap();
	let overhead = last_line_width(&result) + first_line_width(comment.trim());
	let rewrite_post_comment = |item_max_width: &mut Option<usize>| {
	if item_max_width.is_none() && !last && !inner_item.contains('\n') {
	*item_max_width = Some(max_width_of_item_with_post_comment(
	&cloned_items,
	i,
	overhead,
	formatting.config.max_width(),
	));
	}
	let overhead = if starts_with_newline(comment) {
	0
	} else if let Some(max_width) = *item_max_width {
	max_width + 2
	} else {
	// 1 = space between item and comment.
	item_last_line_width + 1
	};
	let width = formatting.shape.width.checked_sub(overhead).unwrap_or(1);
	let offset = formatting.shape.indent + overhead;
	let comment_shape = Shape::legacy(width, offset);
	let block_style = if !formatting.ends_with_newline && last {
	true
	} else if starts_with_newline(comment) {
	false
	} else {
	comment.trim().contains('\n') || comment.trim().len() > width
	};
	rewrite_comment(
	comment.trim_start(),
	block_style,
	comment_shape,
	formatting.config,
	)
	};
	let mut formatted_comment = rewrite_post_comment(&mut item_max_width)?;
	if !starts_with_newline(comment) {
	if formatting.align_comments {
	let mut comment_alignment =
	post_comment_alignment(item_max_width, inner_item.len());
	if first_line_width(&formatted_comment)
	+ last_line_width(&result)
	+ comment_alignment
	+ 1
	> formatting.config.max_width()
	{
	item_max_width = None;
	formatted_comment = rewrite_post_comment(&mut item_max_width)?;
	comment_alignment =
	post_comment_alignment(item_max_width, inner_item.len());
	}
	for _ in 0..=comment_alignment {
	result.push(' ');
	}
	}
	// An additional space for the missing trailing separator (or
	// if we skipped alignment above).
	if !formatting.align_comments
	|| (last
	&& item_max_width.is_some()
	&& !separate
	&& !formatting.separator.is_empty())
	{
	result.push(' ');
	}
	} else {
	result.push('\n');
	result.push_str(indent_str);
	}
	if formatted_comment.contains('\n') {
	item_max_width = None;
	}
	result.push_str(&formatted_comment);
	} else {
	item_max_width = None;
	}

[ytmimi]

linking tracking issue for normalize_comments #3350