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Support comments in trait bounds #5059

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37 changes: 32 additions & 5 deletions src/comment.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,26 @@ pub(crate) fn combine_strs_with_missing_comments(
span: Span,
shape: Shape,
allow_extend: bool,
) -> Option<String> {
combine_lines_with_missing_comments(
context,
prev_str,
next_str,
span,
shape,
false,
allow_extend,
)
}

pub(crate) fn combine_lines_with_missing_comments(
context: &RewriteContext<'_>,
prev_str: &str,
next_str: &str,
span: Span,
shape: Shape,
allow_multiline_join: bool,
allow_extend: bool,
) -> Option<String> {
trace!(
"combine_strs_with_missing_comments `{}` `{}` {:?} {:?}",
Expand All @@ -171,7 +191,8 @@ pub(crate) fn combine_strs_with_missing_comments(
let mut result =
String::with_capacity(prev_str.len() + next_str.len() + shape.indent.width() + 128);
result.push_str(prev_str);
let mut allow_one_line = !prev_str.contains('\n') && !next_str.contains('\n');
let contains_nl = prev_str.contains('\n') || next_str.contains('\n');
let mut allow_line_join = allow_multiline_join || !contains_nl;
let first_sep =
if prev_str.is_empty() || next_str.is_empty() || trimmed_last_line_width(prev_str) == 0 {
""
Expand Down Expand Up @@ -213,22 +234,28 @@ pub(crate) fn combine_strs_with_missing_comments(
} else {
let one_line_width = last_line_width(prev_str) + first_line_width(&missing_comment) + 1;
if prefer_same_line && one_line_width <= shape.width {
Cow::from(" ")
if prev_str.ends_with(" ") {
Cow::from("")
} else {
Cow::from(" ")
}
} else {
indent.to_string_with_newline(config)
}
};
result.push_str(&first_sep);
result.push_str(&missing_comment);

let second_sep = if missing_comment.is_empty() || next_str.is_empty() {
let skip_second_sep =
missing_comment.is_empty() || next_str.is_empty() || next_str.starts_with("\n");
let second_sep = if skip_second_sep {
Cow::from("")
} else if missing_comment.starts_with("//") {
indent.to_string_with_newline(config)
} else {
one_line_width += missing_comment.len() + first_sep.len() + 1;
allow_one_line &= !missing_comment.starts_with("//") && !missing_comment.contains('\n');
if prefer_same_line && allow_one_line && one_line_width <= shape.width {
allow_line_join &= !missing_comment.starts_with("//") && !missing_comment.contains('\n');
if prefer_same_line && allow_line_join && one_line_width <= shape.width {
Cow::from(" ")
} else {
indent.to_string_with_newline(config)
Expand Down
42 changes: 30 additions & 12 deletions src/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1938,18 +1938,36 @@ pub(crate) fn rewrite_assign_rhs_with_comments<S: Into<String>, R: Rewrite>(
) -> Option<String> {
let lhs = lhs.into();
let contains_comment = contains_comment(context.snippet(between_span));
let shape = if contains_comment {
shape.block_left(context.config.tab_spaces())?
} else {
shape
};
let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_tactics)?;

if contains_comment {
let rhs = rhs.trim_start();
combine_strs_with_missing_comments(context, &lhs, rhs, between_span, shape, allow_extend)
} else {
Some(lhs + &rhs)
match (contains_comment, rhs_tactics) {
(true, RhsTactics::ForceNextLineWithoutIndent) => {
let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_tactics)?;
let rhs = rhs.trim_start();

combine_strs_with_missing_comments(
context,
&lhs,
rhs,
between_span,
shape.block_left(context.config.tab_spaces())?,
allow_extend,
)
}
(true, RhsTactics::Default | RhsTactics::AllowOverflow) => {
let shape = shape.block_left(context.config.tab_spaces())?;
let rhs = rewrite_assign_rhs_expr(context, &lhs, ex, shape, rhs_tactics)?;
let rhs = rhs.trim_start();

combine_strs_with_missing_comments(
context,
&lhs,
rhs,
between_span,
shape,
allow_extend,
)
}
(false, _) => rewrite_assign_rhs_with(context, lhs, ex, shape, rhs_tactics),
}
}

Expand Down Expand Up @@ -2014,7 +2032,7 @@ fn shape_from_rhs_tactic(
match rhs_tactic {
RhsTactics::ForceNextLineWithoutIndent => shape
.with_max_width(context.config)
.sub_width(shape.indent.width()),
.sub_width(shape.indent.block_indent(context.config).width()),
RhsTactics::Default | RhsTactics::AllowOverflow => {
Shape::indented(shape.indent.block_indent(context.config), context.config)
.sub_width(shape.rhs_overhead(context.config))
Expand Down
83 changes: 48 additions & 35 deletions src/items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1043,28 +1043,56 @@ pub(crate) fn format_trait(
let body_lo = context.snippet_provider.span_after(item.span, "{");

let shape = Shape::indented(offset, context.config).offset_left(result.len())?;

let combine_comment_span =
|lo: BytePos, hi: BytePos, lhs: String, rhs: &str| -> Option<String> {
let span = mk_sp(lo, hi);

if contains_comment(context.snippet(span)) {
combine_strs_with_missing_comments(context, &lhs, rhs, span, shape, true)
} else {
Some(lhs + rhs)
}
};

let generics_str =
rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
result.push_str(&generics_str);

// FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
// Recover the comment before ident.
let comment_lo = context.snippet_provider.span_after(item.span, "trait");
let comment_hi = item.ident.span.lo();
result = combine_comment_span(comment_lo, comment_hi, result, &generics_str)?;

if !generic_bounds.is_empty() {
let ident_hi = context
.snippet_provider
.span_after(item.span, &item.ident.as_str());
let bound_hi = generic_bounds.last().unwrap().span().hi();
let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
if contains_comment(snippet) {
return None;
}
// Recover the comment before the colon.
let comment_lo = generics.span.hi();
let comment_hi = context.snippet_provider.span_before(item.span, ":");
result = combine_comment_span(comment_lo, comment_hi, result, ":")?;

result = rewrite_assign_rhs_with(
// Recover the comment after the colon.
let comment_lo = context.snippet_provider.span_after(item.span, ":");
let comment_hi = generic_bounds[0].span().lo();
let comment_span = mk_sp(comment_lo, comment_hi);

result = rewrite_assign_rhs_with_comments(
context,
result + ":",
&result,
generic_bounds,
shape,
RhsTactics::ForceNextLineWithoutIndent,
comment_span,
true,
)?;

// Recover the comment following the bounds.
let comment_lo = generic_bounds[generic_bounds.len() - 1].span().hi();
let comment_hi = if generics.where_clause.predicates.is_empty() {
body_lo - BytePos(1)
} else {
generics.where_clause.span.lo()
};

result = combine_comment_span(comment_lo, comment_hi, result, "")?;
}

// Rewrite where-clause.
Expand All @@ -1073,9 +1101,9 @@ pub(crate) fn format_trait(

let where_budget = context.budget(last_line_width(&result));
let pos_before_where = if generic_bounds.is_empty() {
generics.where_clause.span.lo()
generics.span.hi()
} else {
generic_bounds[generic_bounds.len() - 1].span().hi()
generics.where_clause.span.lo()
};
let option = WhereClauseOption::snuggled(&generics_str);
let where_clause_str = rewrite_where_clause(
Expand All @@ -1085,7 +1113,7 @@ pub(crate) fn format_trait(
Shape::legacy(where_budget, offset.block_only()),
where_on_new_line,
"{",
None,
Some(body_lo),
pos_before_where,
option,
)?;
Expand All @@ -1100,26 +1128,11 @@ pub(crate) fn format_trait(
result.push_str(&where_indent.to_string_with_newline(context.config));
}
result.push_str(&where_clause_str);
} else {
let item_snippet = context.snippet(item.span);
if let Some(lo) = item_snippet.find('/') {
// 1 = `{`
let comment_hi = body_lo - BytePos(1);
let comment_lo = item.span.lo() + BytePos(lo as u32);
if comment_lo < comment_hi {
match recover_missing_comment_in_span(
mk_sp(comment_lo, comment_hi),
Shape::indented(offset, context.config),
context,
last_line_width(&result),
) {
Some(ref missing_comment) if !missing_comment.is_empty() => {
result.push_str(missing_comment);
}
_ => (),
}
}
}
} else if generic_bounds.is_empty() {
// 1 = `{`
let comment_lo = item.ident.span.hi();
let comment_hi = body_lo - BytePos(1);
result = combine_comment_span(comment_lo, comment_hi, result, "")?;
}

match context.config.brace_style() {
Expand Down
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