1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // Formatting top-level items - functions, structs, enums, traits, impls.
14 use std::cmp::{min, Ordering};
18 use rustc_target::spec::abi;
19 use syntax::codemap::{self, BytePos, Span};
21 use syntax::{ast, ptr, symbol};
23 use codemap::{LineRangeUtils, SpanUtils};
25 combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
26 recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
28 use config::{BraceStyle, Config, Density, IndentStyle};
30 format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
33 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
34 use macros::{rewrite_macro, MacroPosition};
36 use rewrite::{Rewrite, RewriteContext};
37 use shape::{Indent, Shape};
40 use vertical::rewrite_with_alignment;
41 use visitor::FmtVisitor;
43 const DEFAULT_VISIBILITY: ast::Visibility = codemap::Spanned {
44 node: ast::VisibilityKind::Inherited,
45 span: codemap::DUMMY_SP,
48 fn type_annotation_separator(config: &Config) -> &str {
49 colon_spaces(config.space_before_colon(), config.space_after_colon())
52 // Statements of the form
53 // let pat: ty = init;
54 impl Rewrite for ast::Local {
55 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
57 "Local::rewrite {:?} {} {:?}",
58 self, shape.width, shape.indent
61 skip_out_of_file_lines_range!(context, self.span);
63 if contains_skip(&self.attrs) {
67 let attrs_str = self.attrs.rewrite(context, shape)?;
68 let mut result = if attrs_str.is_empty() {
71 combine_strs_with_missing_comments(
76 self.attrs.last().map(|a| a.span.hi()).unwrap(),
85 let pat_shape = shape.offset_left(4)?;
87 let pat_shape = pat_shape.sub_width(1)?;
88 let pat_str = self.pat.rewrite(context, pat_shape)?;
89 result.push_str(&pat_str);
91 // String that is placed within the assignment pattern and expression.
93 let mut infix = String::with_capacity(32);
95 if let Some(ref ty) = self.ty {
96 let separator = type_annotation_separator(context.config);
97 let indent = shape.indent + last_line_width(&result) + separator.len();
99 let budget = shape.width.checked_sub(indent.width() + 1)?;
100 let rewrite = ty.rewrite(context, Shape::legacy(budget, indent))?;
102 infix.push_str(separator);
103 infix.push_str(&rewrite);
106 if self.init.is_some() {
107 infix.push_str(" =");
113 result.push_str(&infix);
115 if let Some(ref ex) = self.init {
116 // 1 = trailing semicolon;
117 let nested_shape = shape.sub_width(1)?;
119 result = rewrite_assign_rhs(context, result, &**ex, nested_shape)?;
127 // FIXME convert to using rewrite style rather than visitor
128 // FIXME format modules in this style
131 keyword: &'static str,
132 abi: Cow<'static, str>,
133 vis: Option<&'a ast::Visibility>,
134 body: Vec<BodyElement<'a>>,
139 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
142 abi: format_abi(fm.abi, config.force_explicit_abi(), true),
147 .map(|i| BodyElement::ForeignItem(i))
154 enum BodyElement<'a> {
155 // Stmt(&'a ast::Stmt),
156 // Field(&'a ast::Field),
157 // Variant(&'a ast::Variant),
158 // Item(&'a ast::Item),
159 ForeignItem(&'a ast::ForeignItem),
162 /// Represents a fn's signature.
163 pub struct FnSig<'a> {
164 decl: &'a ast::FnDecl,
165 generics: &'a ast::Generics,
167 constness: ast::Constness,
168 defaultness: ast::Defaultness,
169 unsafety: ast::Unsafety,
170 visibility: ast::Visibility,
175 decl: &'a ast::FnDecl,
176 generics: &'a ast::Generics,
177 vis: ast::Visibility,
183 constness: ast::Constness::NotConst,
184 defaultness: ast::Defaultness::Final,
185 unsafety: ast::Unsafety::Normal,
190 pub fn from_method_sig(
191 method_sig: &'a ast::MethodSig,
192 generics: &'a ast::Generics,
195 unsafety: method_sig.unsafety,
196 constness: method_sig.constness.node,
197 defaultness: ast::Defaultness::Final,
199 decl: &*method_sig.decl,
201 visibility: DEFAULT_VISIBILITY,
206 fn_kind: &'a visit::FnKind,
207 generics: &'a ast::Generics,
208 decl: &'a ast::FnDecl,
209 defaultness: ast::Defaultness,
212 visit::FnKind::ItemFn(_, unsafety, constness, abi, visibility, _) => FnSig {
216 constness: constness.node,
219 visibility: visibility.clone(),
221 visit::FnKind::Method(_, method_sig, vis, _) => {
222 let mut fn_sig = FnSig::from_method_sig(method_sig, generics);
223 fn_sig.defaultness = defaultness;
224 if let Some(vis) = vis {
225 fn_sig.visibility = vis.clone();
233 fn to_str(&self, context: &RewriteContext) -> String {
234 let mut result = String::with_capacity(128);
235 // Vis defaultness constness unsafety abi.
236 result.push_str(&*format_visibility(&self.visibility));
237 result.push_str(format_defaultness(self.defaultness));
238 result.push_str(format_constness(self.constness));
239 result.push_str(format_unsafety(self.unsafety));
240 result.push_str(&format_abi(
242 context.config.force_explicit_abi(),
249 impl<'a> FmtVisitor<'a> {
250 fn format_item(&mut self, item: &Item) {
251 self.buffer.push_str(&item.abi);
253 let snippet = self.snippet(item.span);
254 let brace_pos = snippet.find_uncommented("{").unwrap();
257 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
258 // FIXME: this skips comments between the extern keyword and the opening
260 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
261 self.block_indent = self.block_indent.block_indent(self.config);
263 if item.body.is_empty() {
264 self.format_missing_no_indent(item.span.hi() - BytePos(1));
265 self.block_indent = self.block_indent.block_unindent(self.config);
266 let indent_str = self.block_indent.to_string(self.config);
267 self.push_str(&indent_str);
269 for item in &item.body {
270 self.format_body_element(item);
273 self.block_indent = self.block_indent.block_unindent(self.config);
274 self.format_missing_with_indent(item.span.hi() - BytePos(1));
279 self.last_pos = item.span.hi();
282 fn format_body_element(&mut self, element: &BodyElement) {
284 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
288 pub fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
289 let item = Item::from_foreign_mod(fm, span, self.config);
290 self.format_item(&item);
293 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
294 let rewrite = item.rewrite(&self.get_context(), self.shape());
295 self.push_rewrite(item.span(), rewrite);
296 self.last_pos = item.span.hi();
306 inner_attrs: Option<&[ast::Attribute]>,
307 ) -> Option<String> {
308 let context = self.get_context();
310 let mut newline_brace = newline_for_brace(self.config, &fn_sig.generics.where_clause);
312 let (mut result, force_newline_brace) =
313 rewrite_fn_base(&context, indent, ident, fn_sig, span, newline_brace, true)?;
316 if self.config.brace_style() == BraceStyle::AlwaysNextLine
317 || force_newline_brace
318 || last_line_width(&result) + 2 > self.shape().width
320 newline_brace = true;
321 } else if !result.contains('\n') {
322 newline_brace = false;
325 // Prepare for the function body by possibly adding a newline and
327 // FIXME we'll miss anything between the end of the signature and the
328 // start of the body, but we need more spans from the compiler to solve
331 result.push_str(&indent.to_string_with_newline(self.config));
336 self.single_line_fn(&result, block, inner_attrs)
337 .or_else(|| Some(result))
340 pub fn rewrite_required_fn(
344 sig: &ast::MethodSig,
345 generics: &ast::Generics,
347 ) -> Option<String> {
348 // Drop semicolon or it will be interpreted as comment.
349 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
350 let context = self.get_context();
352 let (mut result, _) = rewrite_fn_base(
356 &FnSig::from_method_sig(sig, generics),
362 // Re-attach semicolon
372 inner_attrs: Option<&[ast::Attribute]>,
373 ) -> Option<String> {
374 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
378 let codemap = self.get_context().codemap;
380 if self.config.empty_item_single_line()
381 && is_empty_block(block, None, codemap)
382 && self.block_indent.width() + fn_str.len() + 2 <= self.config.max_width()
384 return Some(format!("{}{{}}", fn_str));
387 if self.config.fn_single_line() && is_simple_block_stmt(block, None, codemap) {
389 if let Some(stmt) = block.stmts.first() {
390 match stmt_expr(stmt) {
392 let suffix = if semicolon_for_expr(&self.get_context(), e) {
398 format_expr(e, ExprType::Statement, &self.get_context(), self.shape())
400 .or_else(|| Some(self.snippet(e.span).to_owned()))
402 None => stmt.rewrite(&self.get_context(), self.shape()),
409 if let Some(res) = rewrite {
410 let width = self.block_indent.width() + fn_str.len() + res.len() + 4;
411 if !res.contains('\n') && width <= self.config.max_width() {
412 return Some(format!("{}{{ {} }}", fn_str, res));
420 pub fn visit_static(&mut self, static_parts: &StaticParts) {
421 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
422 self.push_rewrite(static_parts.span, rewrite);
425 pub fn visit_struct(&mut self, struct_parts: &StructParts) {
426 let is_tuple = struct_parts.def.is_tuple();
427 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
428 .map(|s| if is_tuple { s + ";" } else { s });
429 self.push_rewrite(struct_parts.span, rewrite);
435 vis: &ast::Visibility,
436 enum_def: &ast::EnumDef,
437 generics: &ast::Generics,
440 let enum_header = format_header("enum ", ident, vis);
441 self.push_str(&enum_header);
443 let enum_snippet = self.snippet(span);
444 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
445 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
446 let generics_str = format_generics(
449 self.config.brace_style(),
450 if enum_def.variants.is_empty() {
451 BracePos::ForceSameLine
456 mk_sp(span.lo(), body_start),
457 last_line_width(&enum_header),
459 self.push_str(&generics_str);
461 self.last_pos = body_start;
463 match self.format_variant_list(enum_def, body_start, span.hi()) {
464 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
466 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
467 self.block_indent = self.block_indent.block_unindent(self.config);
472 // Format the body of an enum definition
473 fn format_variant_list(
475 enum_def: &ast::EnumDef,
478 ) -> Option<String> {
479 if enum_def.variants.is_empty() {
480 let mut buffer = String::with_capacity(128);
482 let span = mk_sp(body_lo, body_hi - BytePos(1));
483 format_empty_struct_or_tuple(
493 let mut result = String::with_capacity(1024);
494 let original_offset = self.block_indent;
495 self.block_indent = self.block_indent.block_indent(self.config);
497 let itemize_list_with = |one_line_width: usize| {
499 self.snippet_provider,
500 enum_def.variants.iter(),
504 if !f.node.attrs.is_empty() {
505 f.node.attrs[0].span.lo()
511 |f| self.format_variant(f, one_line_width),
517 let mut items: Vec<_> =
518 itemize_list_with(self.config.width_heuristics().struct_variant_width);
519 // If one of the variants use multiple lines, use multi-lined formatting for all variants.
520 let has_multiline_variant = items.iter().any(|item| item.inner_as_ref().contains('\n'));
521 let has_single_line_variant = items.iter().any(|item| !item.inner_as_ref().contains('\n'));
522 if has_multiline_variant && has_single_line_variant {
523 items = itemize_list_with(0);
526 let shape = self.shape().sub_width(2)?;
527 let fmt = ListFormatting {
528 tactic: DefinitiveListTactic::Vertical,
530 trailing_separator: self.config.trailing_comma(),
531 separator_place: SeparatorPlace::Back,
533 ends_with_newline: true,
534 preserve_newline: true,
539 let list = write_list(&items, &fmt)?;
540 result.push_str(&list);
541 result.push_str(&original_offset.to_string_with_newline(self.config));
546 // Variant of an enum.
547 fn format_variant(&self, field: &ast::Variant, one_line_width: usize) -> Option<String> {
548 if contains_skip(&field.node.attrs) {
549 let lo = field.node.attrs[0].span.lo();
550 let span = mk_sp(lo, field.span.hi());
551 return Some(self.snippet(span).to_owned());
554 let context = self.get_context();
556 let shape = self.shape().sub_width(1)?;
557 let attrs_str = field.node.attrs.rewrite(&context, shape)?;
562 .map_or(field.span.lo(), |attr| attr.span.hi());
563 let span = mk_sp(lo, field.span.lo());
565 let variant_body = match field.node.data {
566 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
568 &StructParts::from_variant(field),
570 Some(one_line_width),
572 ast::VariantData::Unit(..) => {
573 if let Some(ref expr) = field.node.disr_expr {
574 let lhs = format!("{} =", field.node.ident.name);
575 rewrite_assign_rhs(&context, lhs, &*expr.value, shape)?
577 field.node.ident.name.to_string()
582 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
585 fn visit_impl_items(&mut self, items: &[ast::ImplItem]) {
586 if self.get_context().config.reorder_impl_items() {
587 // Create visitor for each items, then reorder them.
588 let mut buffer = vec![];
590 self.visit_impl_item(item);
591 buffer.push((self.buffer.clone(), item.clone()));
594 // type -> const -> macro -> method
595 use ast::ImplItemKind::*;
596 fn need_empty_line(a: &ast::ImplItemKind, b: &ast::ImplItemKind) -> bool {
598 (Type(..), Type(..)) | (Const(..), Const(..)) => false,
603 buffer.sort_by(|(_, a), (_, b)| match (&a.node, &b.node) {
604 (Type(..), _) => Ordering::Less,
605 (_, Type(..)) => Ordering::Greater,
606 (Const(..), _) => Ordering::Less,
607 (_, Const(..)) => Ordering::Greater,
608 (Macro(..), _) => Ordering::Less,
609 (_, Macro(..)) => Ordering::Greater,
610 _ => a.span.lo().cmp(&b.span.lo()),
612 let mut prev_kind = None;
613 for (buf, item) in buffer {
614 // Make sure that there are at least a single empty line between
615 // different impl items.
618 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.node))
622 let indent_str = self.block_indent.to_string_with_newline(self.config);
623 self.push_str(&indent_str);
624 self.push_str(buf.trim());
625 prev_kind = Some(item.node.clone());
629 self.visit_impl_item(item);
636 context: &RewriteContext,
639 where_span_end: Option<BytePos>,
640 ) -> Option<String> {
641 if let ast::ItemKind::Impl(_, _, _, ref generics, _, ref self_ty, ref items) = item.node {
642 let mut result = String::with_capacity(128);
643 let ref_and_type = format_impl_ref_and_type(context, item, offset)?;
644 let sep = offset.to_string_with_newline(context.config);
645 result.push_str(&ref_and_type);
647 let where_budget = if result.contains('\n') {
648 context.config.max_width()
650 context.budget(last_line_width(&result))
653 let mut option = WhereClauseOption::snuggled(&ref_and_type);
654 let snippet = context.snippet(item.span);
655 let open_pos = snippet.find_uncommented("{")? + 1;
656 if !contains_comment(&snippet[open_pos..])
658 && generics.where_clause.predicates.len() == 1
659 && !result.contains('\n')
661 option.suppress_comma();
663 option.compress_where();
666 let mut where_clause_str = rewrite_where_clause(
668 &generics.where_clause,
669 context.config.brace_style(),
670 Shape::legacy(where_budget, offset.block_only()),
679 // If there is no where clause, we may have missing comments between the trait name and
680 // the opening brace.
681 if generics.where_clause.predicates.is_empty() {
682 if let Some(hi) = where_span_end {
683 match recover_missing_comment_in_span(
684 mk_sp(self_ty.span.hi(), hi),
685 Shape::indented(offset, context.config),
687 last_line_width(&result),
689 Some(ref missing_comment) if !missing_comment.is_empty() => {
690 result.push_str(missing_comment);
697 if is_impl_single_line(context, items, &result, &where_clause_str, item)? {
698 result.push_str(&where_clause_str);
699 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
700 // if the where_clause contains extra comments AND
701 // there is only one where clause predicate
702 // recover the suppressed comma in single line where_clause formatting
703 if generics.where_clause.predicates.len() == 1 {
704 result.push_str(",");
706 result.push_str(&format!("{}{{{}}}", &sep, &sep));
708 result.push_str(" {}");
713 result.push_str(&where_clause_str);
715 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
716 match context.config.brace_style() {
717 _ if need_newline => result.push_str(&sep),
718 BraceStyle::AlwaysNextLine => result.push_str(&sep),
719 BraceStyle::PreferSameLine => result.push(' '),
720 BraceStyle::SameLineWhere => {
721 if !where_clause_str.is_empty() {
722 result.push_str(&sep);
731 let snippet = context.snippet(item.span);
732 let open_pos = snippet.find_uncommented("{")? + 1;
734 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
735 let mut visitor = FmtVisitor::from_context(context);
736 let item_indent = offset.block_only().block_indent(context.config);
737 visitor.block_indent = item_indent;
738 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
740 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
741 visitor.visit_impl_items(items);
743 visitor.format_missing(item.span.hi() - BytePos(1));
745 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
746 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
748 result.push_str(&inner_indent_str);
749 result.push_str(visitor.buffer.to_string().trim());
750 result.push_str(&outer_indent_str);
753 if result.ends_with('{') && !context.config.empty_item_single_line() {
754 result.push_str(&sep);
764 fn is_impl_single_line(
765 context: &RewriteContext,
766 items: &[ast::ImplItem],
768 where_clause_str: &str,
771 let snippet = context.snippet(item.span);
772 let open_pos = snippet.find_uncommented("{")? + 1;
775 context.config.empty_item_single_line()
777 && !result.contains('\n')
778 && result.len() + where_clause_str.len() <= context.config.max_width()
779 && !contains_comment(&snippet[open_pos..]),
783 fn format_impl_ref_and_type(
784 context: &RewriteContext,
787 ) -> Option<String> {
788 if let ast::ItemKind::Impl(
798 let mut result = String::with_capacity(128);
800 result.push_str(&format_visibility(&item.vis));
801 result.push_str(format_defaultness(defaultness));
802 result.push_str(format_unsafety(unsafety));
804 let lo = context.snippet_provider.span_after(item.span, "impl");
805 let hi = match *trait_ref {
806 Some(ref tr) => tr.path.span.lo(),
807 None => self_ty.span.lo(),
809 let shape = generics_shape_from_config(
811 Shape::indented(offset + last_line_width(&result), context.config),
814 let generics_str = rewrite_generics(context, "impl", generics, shape, mk_sp(lo, hi))?;
815 result.push_str(&generics_str);
817 let polarity_str = if polarity == ast::ImplPolarity::Negative {
823 if let Some(ref trait_ref) = *trait_ref {
824 let result_len = last_line_width(&result);
825 result.push_str(&rewrite_trait_ref(
834 // Try to put the self type in a single line.
836 let trait_ref_overhead = if trait_ref.is_some() { 4 } else { 0 };
837 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
838 // If there is no where clause adapt budget for type formatting to take space and curly
839 // brace into account.
840 match context.config.brace_style() {
841 BraceStyle::AlwaysNextLine => 0,
847 let used_space = last_line_width(&result) + trait_ref_overhead + curly_brace_overhead;
848 // 1 = space before the type.
849 let budget = context.budget(used_space + 1);
850 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
851 if !self_ty_str.contains('\n') {
852 if trait_ref.is_some() {
853 result.push_str(" for ");
857 result.push_str(&self_ty_str);
862 // Couldn't fit the self type on a single line, put it on a new line.
864 // Add indentation of one additional tab.
865 let new_line_offset = offset.block_indent(context.config);
866 result.push_str(&new_line_offset.to_string(context.config));
867 if trait_ref.is_some() {
868 result.push_str("for ");
870 let budget = context.budget(last_line_width(&result));
871 let type_offset = match context.config.indent_style() {
872 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
873 IndentStyle::Block => new_line_offset,
875 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
882 fn rewrite_trait_ref(
883 context: &RewriteContext,
884 trait_ref: &ast::TraitRef,
888 ) -> Option<String> {
889 // 1 = space between generics and trait_ref
890 let used_space = 1 + polarity_str.len() + result_len;
891 let shape = Shape::indented(offset + used_space, context.config);
892 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
893 if !trait_ref_str.contains('\n') {
894 return Some(format!(" {}{}", polarity_str, &trait_ref_str));
897 // We could not make enough space for trait_ref, so put it on new line.
898 let offset = offset.block_indent(context.config);
899 let shape = Shape::indented(offset, context.config);
900 let trait_ref_str = trait_ref.rewrite(context, shape)?;
903 &offset.to_string_with_newline(context.config),
909 pub struct StructParts<'a> {
912 vis: &'a ast::Visibility,
913 def: &'a ast::VariantData,
914 generics: Option<&'a ast::Generics>,
918 impl<'a> StructParts<'a> {
919 fn format_header(&self) -> String {
920 format_header(self.prefix, self.ident, self.vis)
923 fn from_variant(variant: &'a ast::Variant) -> Self {
926 ident: variant.node.ident,
927 vis: &DEFAULT_VISIBILITY,
928 def: &variant.node.data,
934 pub fn from_item(item: &'a ast::Item) -> Self {
935 let (prefix, def, generics) = match item.node {
936 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
937 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
945 generics: Some(generics),
952 context: &RewriteContext,
953 struct_parts: &StructParts,
955 one_line_width: Option<usize>,
956 ) -> Option<String> {
957 match *struct_parts.def {
958 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
959 ast::VariantData::Tuple(ref fields, _) => {
960 format_tuple_struct(context, struct_parts, fields, offset)
962 ast::VariantData::Struct(ref fields, _) => {
963 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
968 pub fn format_trait(context: &RewriteContext, item: &ast::Item, offset: Indent) -> Option<String> {
969 if let ast::ItemKind::Trait(
977 let mut result = String::with_capacity(128);
978 let header = format!(
980 format_visibility(&item.vis),
981 format_unsafety(unsafety),
982 format_auto(is_auto),
984 result.push_str(&header);
986 let body_lo = context.snippet_provider.span_after(item.span, "{");
988 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
989 let generics_str = rewrite_generics(
991 &item.ident.to_string(),
994 mk_sp(item.span.lo(), body_lo),
996 result.push_str(&generics_str);
998 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
999 if !generic_bounds.is_empty() {
1000 let ident_hi = context
1002 .span_after(item.span, &format!("{}", item.ident));
1003 let bound_hi = generic_bounds.last().unwrap().span().hi();
1004 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1005 if contains_comment(snippet) {
1009 result = rewrite_assign_rhs_with(
1014 RhsTactics::ForceNextLineWithoutIndent,
1018 // Rewrite where clause.
1019 if !generics.where_clause.predicates.is_empty() {
1020 let where_density = if context.config.indent_style() == IndentStyle::Block {
1026 let where_budget = context.budget(last_line_width(&result));
1027 let pos_before_where = if generic_bounds.is_empty() {
1028 generics.where_clause.span.lo()
1030 generic_bounds[generic_bounds.len() - 1].span().hi()
1032 let option = WhereClauseOption::snuggled(&generics_str);
1033 let where_clause_str = rewrite_where_clause(
1035 &generics.where_clause,
1036 context.config.brace_style(),
1037 Shape::legacy(where_budget, offset.block_only()),
1045 // If the where clause cannot fit on the same line,
1046 // put the where clause on a new line
1047 if !where_clause_str.contains('\n')
1048 && last_line_width(&result) + where_clause_str.len() + offset.width()
1049 > context.config.comment_width()
1051 let width = offset.block_indent + context.config.tab_spaces() - 1;
1052 let where_indent = Indent::new(0, width);
1053 result.push_str(&where_indent.to_string_with_newline(context.config));
1055 result.push_str(&where_clause_str);
1057 let item_snippet = context.snippet(item.span);
1058 if let Some(lo) = item_snippet.find('/') {
1060 let comment_hi = body_lo - BytePos(1);
1061 let comment_lo = item.span.lo() + BytePos(lo as u32);
1062 if comment_lo < comment_hi {
1063 match recover_missing_comment_in_span(
1064 mk_sp(comment_lo, comment_hi),
1065 Shape::indented(offset, context.config),
1067 last_line_width(&result),
1069 Some(ref missing_comment) if !missing_comment.is_empty() => {
1070 result.push_str(missing_comment);
1078 match context.config.brace_style() {
1079 _ if last_line_contains_single_line_comment(&result)
1080 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1082 result.push_str(&offset.to_string_with_newline(context.config));
1084 BraceStyle::AlwaysNextLine => {
1085 result.push_str(&offset.to_string_with_newline(context.config));
1087 BraceStyle::PreferSameLine => result.push(' '),
1088 BraceStyle::SameLineWhere => {
1089 if result.contains('\n')
1090 || (!generics.where_clause.predicates.is_empty() && !trait_items.is_empty())
1092 result.push_str(&offset.to_string_with_newline(context.config));
1100 let snippet = context.snippet(item.span);
1101 let open_pos = snippet.find_uncommented("{")? + 1;
1103 if !trait_items.is_empty() || contains_comment(&snippet[open_pos..]) {
1104 let mut visitor = FmtVisitor::from_context(context);
1105 visitor.block_indent = offset.block_only().block_indent(context.config);
1106 visitor.last_pos = item.span.lo() + BytePos(open_pos as u32);
1108 for item in trait_items {
1109 visitor.visit_trait_item(item);
1112 visitor.format_missing(item.span.hi() - BytePos(1));
1114 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1115 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1117 result.push_str(&inner_indent_str);
1118 result.push_str(visitor.buffer.to_string().trim());
1119 result.push_str(&outer_indent_str);
1120 } else if result.contains('\n') {
1131 pub fn format_trait_alias(
1132 context: &RewriteContext,
1134 generics: &ast::Generics,
1135 generic_bounds: &ast::GenericBounds,
1137 ) -> Option<String> {
1138 let alias = ident.name.as_str();
1139 // 6 = "trait ", 2 = " ="
1140 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1141 let generics_str = rewrite_generics(context, &alias, generics, g_shape, generics.span)?;
1142 let lhs = format!("trait {} =", generics_str);
1144 rewrite_assign_rhs(context, lhs, generic_bounds, shape.sub_width(1)?).map(|s| s + ";")
1147 fn format_unit_struct(context: &RewriteContext, p: &StructParts, offset: Indent) -> Option<String> {
1148 let header_str = format_header(p.prefix, p.ident, p.vis);
1149 let generics_str = if let Some(generics) = p.generics {
1150 let hi = if generics.where_clause.predicates.is_empty() {
1153 generics.where_clause.span.hi()
1158 context.config.brace_style(),
1161 mk_sp(generics.span.lo(), hi),
1162 last_line_width(&header_str),
1167 Some(format!("{}{};", header_str, generics_str))
1170 pub fn format_struct_struct(
1171 context: &RewriteContext,
1172 struct_parts: &StructParts,
1173 fields: &[ast::StructField],
1175 one_line_width: Option<usize>,
1176 ) -> Option<String> {
1177 let mut result = String::with_capacity(1024);
1178 let span = struct_parts.span;
1180 let header_str = struct_parts.format_header();
1181 result.push_str(&header_str);
1183 let header_hi = span.lo() + BytePos(header_str.len() as u32);
1184 let body_lo = context.snippet_provider.span_after(span, "{");
1186 let generics_str = match struct_parts.generics {
1187 Some(g) => format_generics(
1190 context.config.brace_style(),
1191 if fields.is_empty() {
1192 BracePos::ForceSameLine
1197 mk_sp(header_hi, body_lo),
1198 last_line_width(&result),
1201 // 3 = ` {}`, 2 = ` {`.
1202 let overhead = if fields.is_empty() { 3 } else { 2 };
1203 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1204 || context.config.max_width() < overhead + result.len()
1206 format!("\n{}{{", offset.block_only().to_string(context.config))
1213 let overhead = if fields.is_empty() { 1 } else { 0 };
1214 let total_width = result.len() + generics_str.len() + overhead;
1215 if !generics_str.is_empty()
1216 && !generics_str.contains('\n')
1217 && total_width > context.config.max_width()
1220 result.push_str(&offset.to_string(context.config));
1221 result.push_str(generics_str.trim_left());
1223 result.push_str(&generics_str);
1226 if fields.is_empty() {
1227 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1228 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1229 return Some(result);
1233 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1234 let one_line_budget =
1235 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1237 let items_str = rewrite_with_alignment(
1240 Shape::indented(offset, context.config).sub_width(1)?,
1241 mk_sp(body_lo, span.hi()),
1245 if !items_str.contains('\n')
1246 && !result.contains('\n')
1247 && items_str.len() <= one_line_budget
1248 && !last_line_contains_single_line_comment(&items_str)
1250 Some(format!("{} {} }}", result, items_str))
1256 .block_indent(context.config)
1257 .to_string(context.config),
1259 offset.to_string(context.config)
1264 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1266 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1267 _ => default_span.lo(),
1271 // Format tuple or struct without any fields. We need to make sure that the comments
1272 // inside the delimiters are preserved.
1273 fn format_empty_struct_or_tuple(
1274 context: &RewriteContext,
1277 result: &mut String,
1281 // 3 = " {}" or "();"
1282 let used_width = last_line_used_width(&result, offset.width()) + 3;
1283 if used_width > context.config.max_width() {
1284 result.push_str(&offset.to_string_with_newline(context.config))
1286 result.push_str(opener);
1287 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1288 Some(ref s) if s.is_empty() => (),
1290 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1291 let nested_indent_str = offset
1292 .block_indent(context.config)
1293 .to_string_with_newline(context.config);
1294 result.push_str(&nested_indent_str);
1297 if last_line_contains_single_line_comment(s) {
1298 result.push_str(&offset.to_string_with_newline(context.config));
1301 None => result.push_str(context.snippet(span)),
1303 result.push_str(closer);
1306 fn format_tuple_struct(
1307 context: &RewriteContext,
1308 struct_parts: &StructParts,
1309 fields: &[ast::StructField],
1311 ) -> Option<String> {
1312 let mut result = String::with_capacity(1024);
1313 let span = struct_parts.span;
1315 let header_str = struct_parts.format_header();
1316 result.push_str(&header_str);
1318 let body_lo = if fields.is_empty() {
1319 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1322 .span_after(mk_sp(lo, span.hi()), "(")
1326 let body_hi = if fields.is_empty() {
1329 .span_after(mk_sp(body_lo, span.hi()), ")")
1331 // This is a dirty hack to work around a missing `)` from the span of the last field.
1332 let last_arg_span = fields[fields.len() - 1].span;
1333 if context.snippet(last_arg_span).ends_with(')') {
1338 .span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1342 let where_clause_str = match struct_parts.generics {
1344 let budget = context.budget(last_line_width(&header_str));
1345 let shape = Shape::legacy(budget, offset);
1346 let g_span = mk_sp(span.lo(), body_lo);
1347 let generics_str = rewrite_generics(context, "", generics, shape, g_span)?;
1348 result.push_str(&generics_str);
1350 let where_budget = context.budget(last_line_width(&result));
1351 let option = WhereClauseOption::new(true, false);
1352 rewrite_where_clause(
1354 &generics.where_clause,
1355 context.config.brace_style(),
1356 Shape::legacy(where_budget, offset.block_only()),
1357 Density::Compressed,
1365 None => "".to_owned(),
1368 if fields.is_empty() {
1369 let body_hi = context
1371 .span_before(mk_sp(body_lo, span.hi()), ")");
1372 let inner_span = mk_sp(body_lo, body_hi);
1373 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1375 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1376 let fields = &fields.iter().collect::<Vec<_>>();
1377 result = overflow::rewrite_with_parens(
1383 context.config.width_heuristics().fn_call_width,
1388 if !where_clause_str.is_empty() && !where_clause_str.contains('\n')
1389 && (result.contains('\n')
1390 || offset.block_indent + result.len() + where_clause_str.len() + 1
1391 > context.config.max_width())
1393 // We need to put the where clause on a new line, but we didn't
1394 // know that earlier, so the where clause will not be indented properly.
1397 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1400 result.push_str(&where_clause_str);
1405 pub fn rewrite_type_alias(
1406 context: &RewriteContext,
1410 generics: &ast::Generics,
1411 vis: &ast::Visibility,
1413 ) -> Option<String> {
1414 let mut result = String::with_capacity(128);
1416 result.push_str(&format_visibility(vis));
1417 result.push_str("type ");
1420 let g_shape = Shape::indented(indent, context.config)
1421 .offset_left(result.len())?
1424 context.snippet_provider.span_after(span, "type"),
1427 let generics_str = rewrite_generics(context, &ident.to_string(), generics, g_shape, g_span)?;
1428 result.push_str(&generics_str);
1430 let where_budget = context.budget(last_line_width(&result));
1431 let option = WhereClauseOption::snuggled(&result);
1432 let where_clause_str = rewrite_where_clause(
1434 &generics.where_clause,
1435 context.config.brace_style(),
1436 Shape::legacy(where_budget, indent),
1444 result.push_str(&where_clause_str);
1445 if where_clause_str.is_empty() {
1446 result.push_str(" =");
1448 result.push_str(&format!(
1450 indent.to_string_with_newline(context.config)
1455 let ty_shape = Shape::indented(indent, context.config).sub_width(1)?;
1456 rewrite_assign_rhs(context, result, ty, ty_shape).map(|s| s + ";")
1459 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1461 if config.space_before_colon() { " " } else { "" },
1462 if config.space_after_colon() { " " } else { "" },
1466 pub fn rewrite_struct_field_prefix(
1467 context: &RewriteContext,
1468 field: &ast::StructField,
1469 ) -> Option<String> {
1470 let vis = format_visibility(&field.vis);
1471 let type_annotation_spacing = type_annotation_spacing(context.config);
1472 Some(match field.ident {
1473 Some(name) => format!("{}{}{}:", vis, name, type_annotation_spacing.0),
1474 None => format!("{}", vis),
1478 impl Rewrite for ast::StructField {
1479 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1480 rewrite_struct_field(context, self, shape, 0)
1484 pub fn rewrite_struct_field(
1485 context: &RewriteContext,
1486 field: &ast::StructField,
1488 lhs_max_width: usize,
1489 ) -> Option<String> {
1490 if contains_skip(&field.attrs) {
1491 return Some(context.snippet(field.span()).to_owned());
1494 let type_annotation_spacing = type_annotation_spacing(context.config);
1495 let prefix = rewrite_struct_field_prefix(context, field)?;
1497 let attrs_str = field.attrs.rewrite(context, shape)?;
1498 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1499 let missing_span = if field.attrs.is_empty() {
1500 mk_sp(field.span.lo(), field.span.lo())
1502 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1504 let mut spacing = String::from(if field.ident.is_some() {
1505 type_annotation_spacing.1
1509 // Try to put everything on a single line.
1510 let attr_prefix = combine_strs_with_missing_comments(
1518 let overhead = last_line_width(&attr_prefix);
1519 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1520 for _ in 0..lhs_offset {
1523 // In this extreme case we will be missing a space betweeen an attribute and a field.
1524 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1528 .offset_left(overhead + spacing.len())
1529 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1530 if let Some(ref ty) = orig_ty {
1531 if !ty.contains('\n') {
1532 return Some(attr_prefix + &spacing + ty);
1536 let is_prefix_empty = prefix.is_empty();
1537 // We must use multiline. We are going to put attributes and a field on different lines.
1538 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, shape)?;
1539 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1540 let field_str = if is_prefix_empty {
1541 field_str.trim_left()
1545 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1548 pub struct StaticParts<'a> {
1550 vis: &'a ast::Visibility,
1553 mutability: ast::Mutability,
1554 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1555 defaultness: Option<ast::Defaultness>,
1559 impl<'a> StaticParts<'a> {
1560 pub fn from_item(item: &'a ast::Item) -> Self {
1561 let (prefix, ty, mutability, expr) = match item.node {
1562 ast::ItemKind::Static(ref ty, mutability, ref expr) => ("static", ty, mutability, expr),
1563 ast::ItemKind::Const(ref ty, ref expr) => {
1564 ("const", ty, ast::Mutability::Immutable, expr)
1566 _ => unreachable!(),
1574 expr_opt: Some(expr),
1580 pub fn from_trait_item(ti: &'a ast::TraitItem) -> Self {
1581 let (ty, expr_opt) = match ti.node {
1582 ast::TraitItemKind::Const(ref ty, ref expr_opt) => (ty, expr_opt),
1583 _ => unreachable!(),
1587 vis: &DEFAULT_VISIBILITY,
1590 mutability: ast::Mutability::Immutable,
1591 expr_opt: expr_opt.as_ref(),
1597 pub fn from_impl_item(ii: &'a ast::ImplItem) -> Self {
1598 let (ty, expr) = match ii.node {
1599 ast::ImplItemKind::Const(ref ty, ref expr) => (ty, expr),
1600 _ => unreachable!(),
1607 mutability: ast::Mutability::Immutable,
1608 expr_opt: Some(expr),
1609 defaultness: Some(ii.defaultness),
1616 context: &RewriteContext,
1617 static_parts: &StaticParts,
1619 ) -> Option<String> {
1620 let colon = colon_spaces(
1621 context.config.space_before_colon(),
1622 context.config.space_after_colon(),
1624 let mut prefix = format!(
1626 format_visibility(static_parts.vis),
1627 static_parts.defaultness.map_or("", format_defaultness),
1628 static_parts.prefix,
1629 format_mutability(static_parts.mutability),
1635 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1636 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1637 Some(ty_str) => ty_str,
1639 if prefix.ends_with(' ') {
1642 let nested_indent = offset.block_indent(context.config);
1643 let nested_shape = Shape::indented(nested_indent, context.config);
1644 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1647 nested_indent.to_string_with_newline(context.config),
1653 if let Some(expr) = static_parts.expr_opt {
1654 let lhs = format!("{}{} =", prefix, ty_str);
1656 let remaining_width = context.budget(offset.block_indent + 1);
1661 Shape::legacy(remaining_width, offset.block_only()),
1662 ).and_then(|res| recover_comment_removed(res, static_parts.span, context))
1663 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1665 Some(format!("{}{};", prefix, ty_str))
1669 pub fn rewrite_associated_type(
1671 ty_opt: Option<&ptr::P<ast::Ty>>,
1672 generic_bounds_opt: Option<&ast::GenericBounds>,
1673 context: &RewriteContext,
1675 ) -> Option<String> {
1676 let prefix = format!("type {}", ident);
1678 let type_bounds_str = if let Some(bounds) = generic_bounds_opt {
1679 if bounds.is_empty() {
1683 let shape = Shape::indented(indent, context.config).offset_left(prefix.len() + 2)?;
1684 bounds.rewrite(context, shape).map(|s| format!(": {}", s))?
1690 if let Some(ty) = ty_opt {
1692 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1693 let lhs = format!("{}{} =", prefix, type_bounds_str);
1694 rewrite_assign_rhs(context, lhs, &**ty, shape).map(|s| s + ";")
1696 Some(format!("{}{};", prefix, type_bounds_str))
1700 pub fn rewrite_associated_impl_type(
1702 defaultness: ast::Defaultness,
1703 ty_opt: Option<&ptr::P<ast::Ty>>,
1704 generic_bounds_opt: Option<&ast::GenericBounds>,
1705 context: &RewriteContext,
1707 ) -> Option<String> {
1708 let result = rewrite_associated_type(ident, ty_opt, generic_bounds_opt, context, indent)?;
1711 ast::Defaultness::Default => Some(format!("default {}", result)),
1716 impl Rewrite for ast::FunctionRetTy {
1717 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1719 ast::FunctionRetTy::Default(_) => Some(String::new()),
1720 ast::FunctionRetTy::Ty(ref ty) => {
1721 let inner_width = shape.width.checked_sub(3)?;
1722 ty.rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1723 .map(|r| format!("-> {}", r))
1729 fn is_empty_infer(context: &RewriteContext, ty: &ast::Ty) -> bool {
1731 ast::TyKind::Infer => {
1732 let original = context.snippet(ty.span);
1739 impl Rewrite for ast::Arg {
1740 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
1741 if is_named_arg(self) {
1742 let mut result = self
1744 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1746 if !is_empty_infer(context, &*self.ty) {
1747 if context.config.space_before_colon() {
1748 result.push_str(" ");
1750 result.push_str(":");
1751 if context.config.space_after_colon() {
1752 result.push_str(" ");
1754 let overhead = last_line_width(&result);
1755 let max_width = shape.width.checked_sub(overhead)?;
1758 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
1759 result.push_str(&ty_str);
1764 self.ty.rewrite(context, shape)
1769 fn rewrite_explicit_self(
1770 explicit_self: &ast::ExplicitSelf,
1772 context: &RewriteContext,
1773 ) -> Option<String> {
1774 match explicit_self.node {
1775 ast::SelfKind::Region(lt, m) => {
1776 let mut_str = format_mutability(m);
1779 let lifetime_str = l.rewrite(
1781 Shape::legacy(context.config.max_width(), Indent::empty()),
1783 Some(format!("&{} {}self", lifetime_str, mut_str))
1785 None => Some(format!("&{}self", mut_str)),
1788 ast::SelfKind::Explicit(ref ty, _) => {
1789 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1791 let mutability = explicit_self_mutability(&args[0]);
1792 let type_str = ty.rewrite(
1794 Shape::legacy(context.config.max_width(), Indent::empty()),
1799 format_mutability(mutability),
1803 ast::SelfKind::Value(_) => {
1804 assert!(!args.is_empty(), "&[ast::Arg] shouldn't be empty.");
1806 let mutability = explicit_self_mutability(&args[0]);
1808 Some(format!("{}self", format_mutability(mutability)))
1813 // Hacky solution caused by absence of `Mutability` in `SelfValue` and
1814 // `SelfExplicit` variants of `ast::ExplicitSelf_`.
1815 fn explicit_self_mutability(arg: &ast::Arg) -> ast::Mutability {
1816 if let ast::PatKind::Ident(ast::BindingMode::ByValue(mutability), _, _) = arg.pat.node {
1823 pub fn span_lo_for_arg(arg: &ast::Arg) -> BytePos {
1824 if is_named_arg(arg) {
1831 pub fn span_hi_for_arg(context: &RewriteContext, arg: &ast::Arg) -> BytePos {
1833 ast::TyKind::Infer if context.snippet(arg.ty.span) == "_" => arg.ty.span.hi(),
1834 ast::TyKind::Infer if is_named_arg(arg) => arg.pat.span.hi(),
1835 _ => arg.ty.span.hi(),
1839 pub fn is_named_arg(arg: &ast::Arg) -> bool {
1840 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
1841 ident != symbol::keywords::Invalid.ident()
1847 // Return type is (result, force_new_line_for_brace)
1849 context: &RewriteContext,
1854 newline_brace: bool,
1856 ) -> Option<(String, bool)> {
1857 let mut force_new_line_for_brace = false;
1859 let where_clause = &fn_sig.generics.where_clause;
1861 let mut result = String::with_capacity(1024);
1862 result.push_str(&fn_sig.to_str(context));
1865 result.push_str("fn ");
1868 let overhead = if has_body && !newline_brace {
1875 let used_width = last_line_used_width(&result, indent.width());
1876 let one_line_budget = context.budget(used_width + overhead);
1878 width: one_line_budget,
1882 let fd = fn_sig.decl;
1883 let g_span = mk_sp(span.lo(), fd.output.span().lo());
1885 rewrite_generics(context, &ident.to_string(), fn_sig.generics, shape, g_span)?;
1886 result.push_str(&generics_str);
1888 let snuggle_angle_bracket = generics_str
1891 .map_or(false, |l| l.trim_left().len() == 1);
1893 // Note that the width and indent don't really matter, we'll re-layout the
1894 // return type later anyway.
1897 .rewrite(context, Shape::indented(indent, context.config))?;
1899 let multi_line_ret_str = ret_str.contains('\n');
1900 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
1903 let (one_line_budget, multi_line_budget, mut arg_indent) = compute_budgets_for_args(
1914 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, arg_indent: {:?}",
1915 one_line_budget, multi_line_budget, arg_indent
1918 // Check if vertical layout was forced.
1919 if one_line_budget == 0 {
1920 if snuggle_angle_bracket {
1923 result.push_str("(");
1924 if context.config.indent_style() == IndentStyle::Visual {
1925 result.push_str(&arg_indent.to_string_with_newline(context.config));
1932 // Skip `pub(crate)`.
1933 let lo_after_visibility = get_bytepos_after_visibility(&fn_sig.visibility, span);
1934 // A conservative estimation, to goal is to be over all parens in generics
1935 let args_start = fn_sig
1940 .map_or(lo_after_visibility, |param| param.span().hi());
1941 let args_end = if fd.inputs.is_empty() {
1944 .span_after(mk_sp(args_start, span.hi()), ")")
1946 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
1947 context.snippet_provider.span_after(last_span, ")")
1949 let args_span = mk_sp(
1952 .span_after(mk_sp(args_start, span.hi()), "("),
1955 let arg_str = rewrite_args(
1958 fd.get_self().as_ref(),
1965 generics_str.contains('\n'),
1968 let put_args_in_block = match context.config.indent_style() {
1969 IndentStyle::Block => arg_str.contains('\n') || arg_str.len() > one_line_budget,
1971 } && !fd.inputs.is_empty();
1973 let mut args_last_line_contains_comment = false;
1974 if put_args_in_block {
1975 arg_indent = indent.block_indent(context.config);
1976 result.push_str(&arg_indent.to_string_with_newline(context.config));
1977 result.push_str(&arg_str);
1978 result.push_str(&indent.to_string_with_newline(context.config));
1981 result.push_str(&arg_str);
1982 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
1983 // Put the closing brace on the next line if it overflows the max width.
1985 if fd.inputs.is_empty() && used_width + 1 > context.config.max_width() {
1988 // If the last line of args contains comment, we cannot put the closing paren
1989 // on the same line.
1993 .map_or(false, |last_line| last_line.contains("//"))
1995 args_last_line_contains_comment = true;
1996 result.push_str(&arg_indent.to_string_with_newline(context.config));
2002 if let ast::FunctionRetTy::Ty(..) = fd.output {
2003 let ret_should_indent = match context.config.indent_style() {
2004 // If our args are block layout then we surely must have space.
2005 IndentStyle::Block if put_args_in_block || fd.inputs.is_empty() => false,
2006 _ if args_last_line_contains_comment => false,
2007 _ if result.contains('\n') || multi_line_ret_str => true,
2009 // If the return type would push over the max width, then put the return type on
2010 // a new line. With the +1 for the signature length an additional space between
2011 // the closing parenthesis of the argument and the arrow '->' is considered.
2012 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2014 // If there is no where clause, take into account the space after the return type
2016 if where_clause.predicates.is_empty() {
2020 sig_length > context.config.max_width()
2023 let ret_indent = if ret_should_indent {
2024 let indent = if arg_str.is_empty() {
2025 // Aligning with non-existent args looks silly.
2026 force_new_line_for_brace = true;
2029 // FIXME: we might want to check that using the arg indent
2030 // doesn't blow our budget, and if it does, then fallback to
2031 // the where clause indent.
2035 result.push_str(&indent.to_string_with_newline(context.config));
2039 Indent::new(indent.block_indent, last_line_width(&result))
2042 if multi_line_ret_str || ret_should_indent {
2043 // Now that we know the proper indent and width, we need to
2044 // re-layout the return type.
2047 .rewrite(context, Shape::indented(ret_indent, context.config))?;
2048 result.push_str(&ret_str);
2050 result.push_str(&ret_str);
2053 // Comment between return type and the end of the decl.
2054 let snippet_lo = fd.output.span().hi();
2055 if where_clause.predicates.is_empty() {
2056 let snippet_hi = span.hi();
2057 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2058 // Try to preserve the layout of the original snippet.
2059 let original_starts_with_newline = snippet
2061 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2062 let original_ends_with_newline = snippet
2063 .rfind(|c| c != ' ')
2064 .map_or(false, |i| snippet[i..].ends_with('\n'));
2065 let snippet = snippet.trim();
2066 if !snippet.is_empty() {
2067 result.push(if original_starts_with_newline {
2072 result.push_str(snippet);
2073 if original_ends_with_newline {
2074 force_new_line_for_brace = true;
2080 let pos_before_where = match fd.output {
2081 ast::FunctionRetTy::Default(..) => args_span.hi(),
2082 ast::FunctionRetTy::Ty(ref ty) => ty.span.hi(),
2085 let is_args_multi_lined = arg_str.contains('\n');
2087 let option = WhereClauseOption::new(!has_body, put_args_in_block && ret_str.is_empty());
2088 let where_clause_str = rewrite_where_clause(
2091 context.config.brace_style(),
2092 Shape::indented(indent, context.config),
2098 is_args_multi_lined,
2100 // If there are neither where clause nor return type, we may be missing comments between
2102 if where_clause_str.is_empty() {
2103 if let ast::FunctionRetTy::Default(ret_span) = fd.output {
2104 match recover_missing_comment_in_span(
2105 mk_sp(args_span.hi(), ret_span.hi()),
2108 last_line_width(&result),
2110 Some(ref missing_comment) if !missing_comment.is_empty() => {
2111 result.push_str(missing_comment);
2112 force_new_line_for_brace = true;
2119 result.push_str(&where_clause_str);
2121 force_new_line_for_brace |= last_line_contains_single_line_comment(&result);
2122 force_new_line_for_brace |= is_args_multi_lined && context.config.where_single_line();
2123 Some((result, force_new_line_for_brace))
2126 #[derive(Copy, Clone)]
2127 struct WhereClauseOption {
2128 suppress_comma: bool, // Force no trailing comma
2129 snuggle: bool, // Do not insert newline before `where`
2130 compress_where: bool, // Try single line where clause instead of vertical layout
2133 impl WhereClauseOption {
2134 pub fn new(suppress_comma: bool, snuggle: bool) -> WhereClauseOption {
2138 compress_where: false,
2142 pub fn snuggled(current: &str) -> WhereClauseOption {
2144 suppress_comma: false,
2145 snuggle: last_line_width(current) == 1,
2146 compress_where: false,
2150 pub fn suppress_comma(&mut self) {
2151 self.suppress_comma = true
2154 pub fn compress_where(&mut self) {
2155 self.compress_where = true
2158 pub fn snuggle(&mut self) {
2164 context: &RewriteContext,
2166 explicit_self: Option<&ast::ExplicitSelf>,
2167 one_line_budget: usize,
2168 multi_line_budget: usize,
2173 generics_str_contains_newline: bool,
2174 ) -> Option<String> {
2175 let mut arg_item_strs = args
2177 .map(|arg| arg.rewrite(context, Shape::legacy(multi_line_budget, arg_indent)))
2178 .collect::<Option<Vec<_>>>()?;
2180 // Account for sugary self.
2181 // FIXME: the comment for the self argument is dropped. This is blocked
2182 // on rust issue #27522.
2183 let min_args = explicit_self
2184 .and_then(|explicit_self| rewrite_explicit_self(explicit_self, args, context))
2185 .map_or(1, |self_str| {
2186 arg_item_strs[0] = self_str;
2190 // Comments between args.
2191 let mut arg_items = Vec::new();
2193 arg_items.push(ListItem::from_str(""));
2196 // FIXME(#21): if there are no args, there might still be a comment, but
2197 // without spans for the comment or parens, there is no chance of
2198 // getting it right. You also don't get to put a comment on self, unless
2200 if args.len() >= min_args || variadic {
2201 let comment_span_start = if min_args == 2 {
2202 let second_arg_start = if arg_has_pattern(&args[1]) {
2203 args[1].pat.span.lo()
2205 args[1].ty.span.lo()
2207 let reduced_span = mk_sp(span.lo(), second_arg_start);
2209 context.snippet_provider.span_after_last(reduced_span, ",")
2214 enum ArgumentKind<'a> {
2215 Regular(&'a ast::Arg),
2219 let variadic_arg = if variadic {
2220 let variadic_span = mk_sp(args.last().unwrap().ty.span.hi(), span.hi());
2221 let variadic_start =
2222 context.snippet_provider.span_after(variadic_span, "...") - BytePos(3);
2223 Some(ArgumentKind::Variadic(variadic_start))
2228 let more_items = itemize_list(
2229 context.snippet_provider,
2230 args[min_args - 1..]
2232 .map(ArgumentKind::Regular)
2233 .chain(variadic_arg),
2237 ArgumentKind::Regular(arg) => span_lo_for_arg(arg),
2238 ArgumentKind::Variadic(start) => start,
2241 ArgumentKind::Regular(arg) => arg.ty.span.hi(),
2242 ArgumentKind::Variadic(start) => start + BytePos(3),
2245 ArgumentKind::Regular(..) => None,
2246 ArgumentKind::Variadic(..) => Some("...".to_owned()),
2253 arg_items.extend(more_items);
2256 let fits_in_one_line = !generics_str_contains_newline
2257 && (arg_items.is_empty()
2258 || arg_items.len() == 1 && arg_item_strs[0].len() <= one_line_budget);
2260 for (item, arg) in arg_items.iter_mut().zip(arg_item_strs) {
2261 item.item = Some(arg);
2264 let last_line_ends_with_comment = arg_items
2267 .and_then(|item| item.post_comment.as_ref())
2268 .map_or(false, |s| s.trim().starts_with("//"));
2270 let (indent, trailing_comma) = match context.config.indent_style() {
2271 IndentStyle::Block if fits_in_one_line => {
2272 (indent.block_indent(context.config), SeparatorTactic::Never)
2274 IndentStyle::Block => (
2275 indent.block_indent(context.config),
2276 context.config.trailing_comma(),
2278 IndentStyle::Visual if last_line_ends_with_comment => {
2279 (arg_indent, context.config.trailing_comma())
2281 IndentStyle::Visual => (arg_indent, SeparatorTactic::Never),
2284 let tactic = definitive_tactic(
2286 context.config.fn_args_density().to_list_tactic(),
2290 let budget = match tactic {
2291 DefinitiveListTactic::Horizontal => one_line_budget,
2292 _ => multi_line_budget,
2295 debug!("rewrite_args: budget: {}, tactic: {:?}", budget, tactic);
2297 let fmt = ListFormatting {
2300 trailing_separator: if variadic {
2301 SeparatorTactic::Never
2305 separator_place: SeparatorPlace::Back,
2306 shape: Shape::legacy(budget, indent),
2307 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2308 preserve_newline: true,
2310 config: context.config,
2313 write_list(&arg_items, &fmt)
2316 fn arg_has_pattern(arg: &ast::Arg) -> bool {
2317 if let ast::PatKind::Ident(_, ident, _) = arg.pat.node {
2318 ident != symbol::keywords::Invalid.ident()
2324 fn compute_budgets_for_args(
2325 context: &RewriteContext,
2329 newline_brace: bool,
2331 force_vertical_layout: bool,
2332 ) -> Option<((usize, usize, Indent))> {
2334 "compute_budgets_for_args {} {:?}, {}, {}",
2340 // Try keeping everything on the same line.
2341 if !result.contains('\n') && !force_vertical_layout {
2342 // 2 = `()`, 3 = `() `, space is before ret_string.
2343 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2344 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2354 let one_line_budget = context.budget(used_space);
2356 if one_line_budget > 0 {
2358 let (indent, multi_line_budget) = match context.config.indent_style() {
2359 IndentStyle::Block => {
2360 let indent = indent.block_indent(context.config);
2361 (indent, context.budget(indent.width() + 1))
2363 IndentStyle::Visual => {
2364 let indent = indent + result.len() + 1;
2365 let multi_line_overhead = indent.width() + if newline_brace { 2 } else { 4 };
2366 (indent, context.budget(multi_line_overhead))
2370 return Some((one_line_budget, multi_line_budget, indent));
2374 // Didn't work. we must force vertical layout and put args on a newline.
2375 let new_indent = indent.block_indent(context.config);
2376 let used_space = match context.config.indent_style() {
2378 IndentStyle::Block => new_indent.width() + 1,
2379 // Account for `)` and possibly ` {`.
2380 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2382 Some((0, context.budget(used_space), new_indent))
2385 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> bool {
2386 let predicate_count = where_clause.predicates.len();
2388 if config.where_single_line() && predicate_count == 1 {
2391 let brace_style = config.brace_style();
2393 brace_style == BraceStyle::AlwaysNextLine
2394 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0)
2397 fn rewrite_generics(
2398 context: &RewriteContext,
2400 generics: &ast::Generics,
2403 ) -> Option<String> {
2404 // FIXME: convert bounds to where clauses where they get too big or if
2405 // there is a where clause at all.
2407 if generics.params.is_empty() {
2408 return Some(ident.to_owned());
2411 let params = &generics.params.iter().map(|e| &*e).collect::<Vec<_>>();
2412 overflow::rewrite_with_angle_brackets(context, ident, params, shape, span)
2415 pub fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2416 match config.indent_style() {
2417 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2418 IndentStyle::Block => {
2422 .block_indent(config.tab_spaces())
2423 .with_max_width(config)
2429 fn rewrite_where_clause_rfc_style(
2430 context: &RewriteContext,
2431 where_clause: &ast::WhereClause,
2434 span_end: Option<BytePos>,
2435 span_end_before_where: BytePos,
2436 where_clause_option: WhereClauseOption,
2437 is_args_multi_line: bool,
2438 ) -> Option<String> {
2439 let block_shape = shape.block().with_max_width(context.config);
2441 let (span_before, span_after) =
2442 missing_span_before_after_where(span_end_before_where, where_clause);
2443 let (comment_before, comment_after) =
2444 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2446 let starting_newline = if where_clause_option.snuggle && comment_before.is_empty() {
2449 block_shape.indent.to_string_with_newline(context.config)
2452 let clause_shape = block_shape.block_left(context.config.tab_spaces())?;
2454 let clause_shape = clause_shape.sub_width(1)?;
2455 // each clause on one line, trailing comma (except if suppress_comma)
2456 let span_start = where_clause.predicates[0].span().lo();
2457 // If we don't have the start of the next span, then use the end of the
2458 // predicates, but that means we miss comments.
2459 let len = where_clause.predicates.len();
2460 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2461 let span_end = span_end.unwrap_or(end_of_preds);
2462 let items = itemize_list(
2463 context.snippet_provider,
2464 where_clause.predicates.iter(),
2467 |pred| pred.span().lo(),
2468 |pred| pred.span().hi(),
2469 |pred| pred.rewrite(context, clause_shape),
2474 let where_single_line = context.config.where_single_line() && len == 1 && !is_args_multi_line;
2475 let comma_tactic = if where_clause_option.suppress_comma || where_single_line {
2476 SeparatorTactic::Never
2478 context.config.trailing_comma()
2481 // shape should be vertical only and only if we have `where_single_line` option enabled
2482 // and the number of items of the where clause is equal to 1
2483 let shape_tactic = if where_single_line {
2484 DefinitiveListTactic::Horizontal
2486 DefinitiveListTactic::Vertical
2489 let fmt = ListFormatting {
2490 tactic: shape_tactic,
2492 trailing_separator: comma_tactic,
2493 separator_place: SeparatorPlace::Back,
2494 shape: clause_shape,
2495 ends_with_newline: true,
2496 preserve_newline: true,
2498 config: context.config,
2500 let preds_str = write_list(&items.collect::<Vec<_>>(), &fmt)?;
2502 let comment_separator = |comment: &str, shape: Shape| {
2503 if comment.is_empty() {
2506 shape.indent.to_string_with_newline(context.config)
2509 let newline_before_where = comment_separator(&comment_before, shape);
2510 let newline_after_where = comment_separator(&comment_after, clause_shape);
2513 let clause_sep = if where_clause_option.compress_where
2514 && comment_before.is_empty()
2515 && comment_after.is_empty()
2516 && !preds_str.contains('\n')
2517 && 6 + preds_str.len() <= shape.width || where_single_line
2521 clause_shape.indent.to_string_with_newline(context.config)
2524 "{}{}{}where{}{}{}{}",
2527 newline_before_where,
2528 newline_after_where,
2535 fn rewrite_where_clause(
2536 context: &RewriteContext,
2537 where_clause: &ast::WhereClause,
2538 brace_style: BraceStyle,
2542 span_end: Option<BytePos>,
2543 span_end_before_where: BytePos,
2544 where_clause_option: WhereClauseOption,
2545 is_args_multi_line: bool,
2546 ) -> Option<String> {
2547 if where_clause.predicates.is_empty() {
2548 return Some(String::new());
2551 if context.config.indent_style() == IndentStyle::Block {
2552 return rewrite_where_clause_rfc_style(
2558 span_end_before_where,
2559 where_clause_option,
2564 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2566 let offset = match context.config.indent_style() {
2567 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2568 // 6 = "where ".len()
2569 IndentStyle::Visual => shape.indent + extra_indent + 6,
2571 // FIXME: if indent_style != Visual, then the budgets below might
2572 // be out by a char or two.
2574 let budget = context.config.max_width() - offset.width();
2575 let span_start = where_clause.predicates[0].span().lo();
2576 // If we don't have the start of the next span, then use the end of the
2577 // predicates, but that means we miss comments.
2578 let len = where_clause.predicates.len();
2579 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2580 let span_end = span_end.unwrap_or(end_of_preds);
2581 let items = itemize_list(
2582 context.snippet_provider,
2583 where_clause.predicates.iter(),
2586 |pred| pred.span().lo(),
2587 |pred| pred.span().hi(),
2588 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2593 let item_vec = items.collect::<Vec<_>>();
2594 // FIXME: we don't need to collect here
2595 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2597 let mut comma_tactic = context.config.trailing_comma();
2598 // Kind of a hack because we don't usually have trailing commas in where clauses.
2599 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2600 comma_tactic = SeparatorTactic::Never;
2603 let fmt = ListFormatting {
2606 trailing_separator: comma_tactic,
2607 separator_place: SeparatorPlace::Back,
2608 shape: Shape::legacy(budget, offset),
2609 ends_with_newline: tactic.ends_with_newline(context.config.indent_style()),
2610 preserve_newline: true,
2612 config: context.config,
2614 let preds_str = write_list(&item_vec, &fmt)?;
2616 let end_length = if terminator == "{" {
2617 // If the brace is on the next line we don't need to count it otherwise it needs two
2620 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2621 BraceStyle::PreferSameLine => 2,
2623 } else if terminator == "=" {
2628 if density == Density::Tall
2629 || preds_str.contains('\n')
2630 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2634 (shape.indent + extra_indent).to_string(context.config),
2638 Some(format!(" where {}", preds_str))
2642 fn missing_span_before_after_where(
2643 before_item_span_end: BytePos,
2644 where_clause: &ast::WhereClause,
2646 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2648 let pos_after_where = where_clause.span.lo() + BytePos(5);
2649 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2650 (missing_span_before, missing_span_after)
2653 fn rewrite_comments_before_after_where(
2654 context: &RewriteContext,
2655 span_before_where: Span,
2656 span_after_where: Span,
2658 ) -> Option<(String, String)> {
2659 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2660 let after_comment = rewrite_missing_comment(
2662 shape.block_indent(context.config.tab_spaces()),
2665 Some((before_comment, after_comment))
2668 fn format_header(item_name: &str, ident: ast::Ident, vis: &ast::Visibility) -> String {
2669 format!("{}{}{}", format_visibility(vis), item_name, ident)
2672 #[derive(PartialEq, Eq, Clone, Copy)]
2680 context: &RewriteContext,
2681 generics: &ast::Generics,
2682 brace_style: BraceStyle,
2683 brace_pos: BracePos,
2687 ) -> Option<String> {
2688 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
2689 let mut result = rewrite_generics(context, "", generics, shape, span)?;
2691 let same_line_brace = if !generics.where_clause.predicates.is_empty() || result.contains('\n') {
2692 let budget = context.budget(last_line_used_width(&result, offset.width()));
2693 let mut option = WhereClauseOption::snuggled(&result);
2694 if brace_pos == BracePos::None {
2695 option.suppress_comma = true;
2697 // If the generics are not parameterized then generics.span.hi() == 0,
2698 // so we use span.lo(), which is the position after `struct Foo`.
2699 let span_end_before_where = if !generics.params.is_empty() {
2704 let where_clause_str = rewrite_where_clause(
2706 &generics.where_clause,
2708 Shape::legacy(budget, offset.block_only()),
2712 span_end_before_where,
2716 result.push_str(&where_clause_str);
2717 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine
2718 || (generics.where_clause.predicates.is_empty()
2719 && trimmed_last_line_width(&result) == 1)
2721 brace_pos == BracePos::ForceSameLine
2722 || trimmed_last_line_width(&result) == 1
2723 || brace_style != BraceStyle::AlwaysNextLine
2725 if brace_pos == BracePos::None {
2726 return Some(result);
2728 let total_used_width = last_line_used_width(&result, used_width);
2729 let remaining_budget = context.budget(total_used_width);
2730 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
2731 // and hence we take the closer into account as well for one line budget.
2732 // We assume that the closer has the same length as the opener.
2733 let overhead = if brace_pos == BracePos::ForceSameLine {
2740 let forbid_same_line_brace = overhead > remaining_budget;
2741 if !forbid_same_line_brace && same_line_brace {
2745 result.push_str(&offset.block_only().to_string(context.config));
2752 impl Rewrite for ast::ForeignItem {
2753 fn rewrite(&self, context: &RewriteContext, shape: Shape) -> Option<String> {
2754 let attrs_str = self.attrs.rewrite(context, shape)?;
2755 // Drop semicolon or it will be interpreted as comment.
2756 // FIXME: this may be a faulty span from libsyntax.
2757 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
2759 let item_str = match self.node {
2760 ast::ForeignItemKind::Fn(ref fn_decl, ref generics) => {
2765 &FnSig::new(fn_decl, generics, self.vis.clone()),
2769 ).map(|(s, _)| format!("{};", s))
2771 ast::ForeignItemKind::Static(ref ty, is_mutable) => {
2772 // FIXME(#21): we're dropping potential comments in between the
2773 // function keywords here.
2774 let vis = format_visibility(&self.vis);
2775 let mut_str = if is_mutable { "mut " } else { "" };
2776 let prefix = format!("{}static {}{}:", vis, mut_str, self.ident);
2778 rewrite_assign_rhs(context, prefix, &**ty, shape.sub_width(1)?).map(|s| s + ";")
2780 ast::ForeignItemKind::Ty => {
2781 let vis = format_visibility(&self.vis);
2782 Some(format!("{}type {};", vis, self.ident))
2784 ast::ForeignItemKind::Macro(ref mac) => {
2785 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
2789 let missing_span = if self.attrs.is_empty() {
2790 mk_sp(self.span.lo(), self.span.lo())
2792 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
2794 combine_strs_with_missing_comments(
2805 /// Rewrite an inline mod.
2806 pub fn rewrite_mod(item: &ast::Item) -> String {
2807 let mut result = String::with_capacity(32);
2808 result.push_str(&*format_visibility(&item.vis));
2809 result.push_str("mod ");
2810 result.push_str(&item.ident.to_string());
2815 /// Rewrite `extern crate foo;` WITHOUT attributes.
2816 pub fn rewrite_extern_crate(context: &RewriteContext, item: &ast::Item) -> Option<String> {
2817 assert!(is_extern_crate(item));
2818 let new_str = context.snippet(item.span);
2819 Some(if contains_comment(new_str) {
2822 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
2823 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
2827 /// Returns true for `mod foo;`, false for `mod foo { .. }`.
2828 pub fn is_mod_decl(item: &ast::Item) -> bool {
2830 ast::ItemKind::Mod(ref m) => m.inner.hi() != item.span.hi(),
2835 pub fn is_use_item(item: &ast::Item) -> bool {
2837 ast::ItemKind::Use(_) => true,
2842 pub fn is_extern_crate(item: &ast::Item) -> bool {
2844 ast::ItemKind::ExternCrate(..) => true,