1 // Formatting top-level items - functions, structs, enums, traits, impls.
4 use std::cmp::{max, min, Ordering};
8 use rustc_ast::{ast, ptr};
9 use rustc_span::{symbol, BytePos, Span, DUMMY_SP};
11 use crate::attr::filter_inline_attrs;
13 combine_strs_with_missing_comments, contains_comment, is_last_comment_block,
14 recover_comment_removed, recover_missing_comment_in_span, rewrite_missing_comment,
17 use crate::config::lists::*;
18 use crate::config::{BraceStyle, Config, IndentStyle, Version};
20 is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
21 rewrite_assign_rhs_with_comments, RhsAssignKind, RhsTactics,
23 use crate::lists::{definitive_tactic, itemize_list, write_list, ListFormatting, Separator};
24 use crate::macros::{rewrite_macro, MacroPosition};
26 use crate::rewrite::{Rewrite, RewriteContext};
27 use crate::shape::{Indent, Shape};
28 use crate::source_map::{LineRangeUtils, SpanUtils};
29 use crate::spanned::Spanned;
30 use crate::stmt::Stmt;
31 use crate::types::opaque_ty;
33 use crate::vertical::rewrite_with_alignment;
34 use crate::visitor::FmtVisitor;
36 const DEFAULT_VISIBILITY: ast::Visibility = ast::Visibility {
37 kind: ast::VisibilityKind::Inherited,
42 fn type_annotation_separator(config: &Config) -> &str {
46 // Statements of the form
47 // let pat: ty = init;
48 impl Rewrite for ast::Local {
49 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
51 "Local::rewrite {:?} {} {:?}",
52 self, shape.width, shape.indent
55 skip_out_of_file_lines_range!(context, self.span);
57 if contains_skip(&self.attrs) || matches!(self.kind, ast::LocalKind::InitElse(..)) {
61 let attrs_str = self.attrs.rewrite(context, shape)?;
62 let mut result = if attrs_str.is_empty() {
65 combine_strs_with_missing_comments(
70 self.attrs.last().map(|a| a.span.hi()).unwrap(),
79 let pat_shape = shape.offset_left(4)?;
81 let pat_shape = pat_shape.sub_width(1)?;
82 let pat_str = self.pat.rewrite(context, pat_shape)?;
83 result.push_str(&pat_str);
85 // String that is placed within the assignment pattern and expression.
87 let mut infix = String::with_capacity(32);
89 if let Some(ref ty) = self.ty {
90 let separator = type_annotation_separator(context.config);
91 let ty_shape = if pat_str.contains('\n') {
92 shape.with_max_width(context.config)
96 .offset_left(last_line_width(&result) + separator.len())?
100 let rewrite = ty.rewrite(context, ty_shape)?;
102 infix.push_str(separator);
103 infix.push_str(&rewrite);
106 if self.kind.init().is_some() {
107 infix.push_str(" =");
113 result.push_str(&infix);
115 if let Some((init, _els)) = self.kind.init_else_opt() {
116 // 1 = trailing semicolon;
117 let nested_shape = shape.sub_width(1)?;
119 result = rewrite_assign_rhs(
123 &RhsAssignKind::Expr(&init.kind, init.span),
134 // FIXME convert to using rewrite style rather than visitor
135 // FIXME format modules in this style
139 unsafety: ast::Unsafe,
140 abi: Cow<'static, str>,
141 vis: Option<&'a ast::Visibility>,
142 body: Vec<BodyElement<'a>>,
147 fn from_foreign_mod(fm: &'a ast::ForeignMod, span: Span, config: &Config) -> Item<'a> {
149 unsafety: fm.unsafety,
151 ast::Extern::from_abi(fm.abi),
152 config.force_explicit_abi(),
159 .map(|i| BodyElement::ForeignItem(i))
167 enum BodyElement<'a> {
168 // Stmt(&'a ast::Stmt),
169 // Field(&'a ast::ExprField),
170 // Variant(&'a ast::Variant),
171 // Item(&'a ast::Item),
172 ForeignItem(&'a ast::ForeignItem),
175 /// Represents a fn's signature.
176 pub(crate) struct FnSig<'a> {
177 decl: &'a ast::FnDecl,
178 generics: &'a ast::Generics,
180 is_async: Cow<'a, ast::Async>,
181 constness: ast::Const,
182 defaultness: ast::Defaultness,
183 unsafety: ast::Unsafe,
184 visibility: &'a ast::Visibility,
188 pub(crate) fn from_method_sig(
189 method_sig: &'a ast::FnSig,
190 generics: &'a ast::Generics,
191 visibility: &'a ast::Visibility,
194 unsafety: method_sig.header.unsafety,
195 is_async: Cow::Borrowed(&method_sig.header.asyncness),
196 constness: method_sig.header.constness,
197 defaultness: ast::Defaultness::Final,
198 ext: method_sig.header.ext,
199 decl: &*method_sig.decl,
205 pub(crate) fn from_fn_kind(
206 fn_kind: &'a visit::FnKind<'_>,
207 generics: &'a ast::Generics,
208 decl: &'a ast::FnDecl,
209 defaultness: ast::Defaultness,
212 visit::FnKind::Fn(fn_ctxt, _, fn_sig, vis, _) => match fn_ctxt {
213 visit::FnCtxt::Assoc(..) => {
214 let mut fn_sig = FnSig::from_method_sig(fn_sig, generics, vis);
215 fn_sig.defaultness = defaultness;
221 ext: fn_sig.header.ext,
222 constness: fn_sig.header.constness,
223 is_async: Cow::Borrowed(&fn_sig.header.asyncness),
225 unsafety: fn_sig.header.unsafety,
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(context, self.visibility));
237 result.push_str(format_defaultness(self.defaultness));
238 result.push_str(format_constness(self.constness));
239 result.push_str(format_async(&self.is_async));
240 result.push_str(format_unsafety(self.unsafety));
241 result.push_str(&format_extern(
243 context.config.force_explicit_abi(),
250 impl<'a> FmtVisitor<'a> {
251 fn format_item(&mut self, item: &Item<'_>) {
252 self.buffer.push_str(format_unsafety(item.unsafety));
253 self.buffer.push_str(&item.abi);
255 let snippet = self.snippet(item.span);
256 let brace_pos = snippet.find_uncommented("{").unwrap();
259 if !item.body.is_empty() || contains_comment(&snippet[brace_pos..]) {
260 // FIXME: this skips comments between the extern keyword and the opening
262 self.last_pos = item.span.lo() + BytePos(brace_pos as u32 + 1);
263 self.block_indent = self.block_indent.block_indent(self.config);
265 if !item.body.is_empty() {
266 for item in &item.body {
267 self.format_body_element(item);
271 self.format_missing_no_indent(item.span.hi() - BytePos(1));
272 self.block_indent = self.block_indent.block_unindent(self.config);
273 let indent_str = self.block_indent.to_string(self.config);
274 self.push_str(&indent_str);
278 self.last_pos = item.span.hi();
281 fn format_body_element(&mut self, element: &BodyElement<'_>) {
283 BodyElement::ForeignItem(item) => self.format_foreign_item(item),
287 pub(crate) fn format_foreign_mod(&mut self, fm: &ast::ForeignMod, span: Span) {
288 let item = Item::from_foreign_mod(fm, span, self.config);
289 self.format_item(&item);
292 fn format_foreign_item(&mut self, item: &ast::ForeignItem) {
293 let rewrite = item.rewrite(&self.get_context(), self.shape());
294 let hi = item.span.hi();
295 let span = if item.attrs.is_empty() {
298 mk_sp(item.attrs[0].span.lo(), hi)
300 self.push_rewrite(span, rewrite);
304 pub(crate) fn rewrite_fn_before_block(
307 ident: symbol::Ident,
310 ) -> Option<(String, FnBraceStyle)> {
311 let context = self.get_context();
313 let mut fn_brace_style = newline_for_brace(self.config, &fn_sig.generics.where_clause);
314 let (result, _, force_newline_brace) =
315 rewrite_fn_base(&context, indent, ident, fn_sig, span, fn_brace_style)?;
318 if self.config.brace_style() == BraceStyle::AlwaysNextLine
319 || force_newline_brace
320 || last_line_width(&result) + 2 > self.shape().width
322 fn_brace_style = FnBraceStyle::NextLine
325 Some((result, fn_brace_style))
328 pub(crate) fn rewrite_required_fn(
331 ident: symbol::Ident,
333 vis: &ast::Visibility,
334 generics: &ast::Generics,
336 ) -> Option<String> {
337 // Drop semicolon or it will be interpreted as comment.
338 let span = mk_sp(span.lo(), span.hi() - BytePos(1));
339 let context = self.get_context();
341 let (mut result, ends_with_comment, _) = rewrite_fn_base(
345 &FnSig::from_method_sig(sig, generics, vis),
350 // If `result` ends with a comment, then remember to add a newline
351 if ends_with_comment {
352 result.push_str(&indent.to_string_with_newline(context.config));
355 // Re-attach semicolon
361 pub(crate) fn single_line_fn(
365 inner_attrs: Option<&[ast::Attribute]>,
366 ) -> Option<String> {
367 if fn_str.contains('\n') || inner_attrs.map_or(false, |a| !a.is_empty()) {
371 let context = self.get_context();
373 if self.config.empty_item_single_line()
374 && is_empty_block(&context, block, None)
375 && self.block_indent.width() + fn_str.len() + 3 <= self.config.max_width()
376 && !last_line_contains_single_line_comment(fn_str)
378 return Some(format!("{} {{}}", fn_str));
381 if !self.config.fn_single_line() || !is_simple_block_stmt(&context, block, None) {
385 let res = Stmt::from_ast_node(block.stmts.first()?, true)
386 .rewrite(&self.get_context(), self.shape())?;
388 let width = self.block_indent.width() + fn_str.len() + res.len() + 5;
389 if !res.contains('\n') && width <= self.config.max_width() {
390 Some(format!("{} {{ {} }}", fn_str, res))
396 pub(crate) fn visit_static(&mut self, static_parts: &StaticParts<'_>) {
397 let rewrite = rewrite_static(&self.get_context(), static_parts, self.block_indent);
398 self.push_rewrite(static_parts.span, rewrite);
401 pub(crate) fn visit_struct(&mut self, struct_parts: &StructParts<'_>) {
402 let is_tuple = match struct_parts.def {
403 ast::VariantData::Tuple(..) => true,
406 let rewrite = format_struct(&self.get_context(), struct_parts, self.block_indent, None)
407 .map(|s| if is_tuple { s + ";" } else { s });
408 self.push_rewrite(struct_parts.span, rewrite);
411 pub(crate) fn visit_enum(
413 ident: symbol::Ident,
414 vis: &ast::Visibility,
415 enum_def: &ast::EnumDef,
416 generics: &ast::Generics,
420 format_header(&self.get_context(), "enum ", ident, vis, self.block_indent);
421 self.push_str(&enum_header);
423 let enum_snippet = self.snippet(span);
424 let brace_pos = enum_snippet.find_uncommented("{").unwrap();
425 let body_start = span.lo() + BytePos(brace_pos as u32 + 1);
426 let generics_str = format_generics(
429 self.config.brace_style(),
430 if enum_def.variants.is_empty() {
431 BracePos::ForceSameLine
436 // make a span that starts right after `enum Foo`
437 mk_sp(ident.span.hi(), body_start),
438 last_line_width(&enum_header),
441 self.push_str(&generics_str);
443 self.last_pos = body_start;
445 match self.format_variant_list(enum_def, body_start, span.hi()) {
446 Some(ref s) if enum_def.variants.is_empty() => self.push_str(s),
448 self.push_rewrite(mk_sp(body_start, span.hi()), rw);
449 self.block_indent = self.block_indent.block_unindent(self.config);
454 // Format the body of an enum definition
455 fn format_variant_list(
457 enum_def: &ast::EnumDef,
460 ) -> Option<String> {
461 if enum_def.variants.is_empty() {
462 let mut buffer = String::with_capacity(128);
464 let span = mk_sp(body_lo, body_hi - BytePos(1));
465 format_empty_struct_or_tuple(
475 let mut result = String::with_capacity(1024);
476 let original_offset = self.block_indent;
477 self.block_indent = self.block_indent.block_indent(self.config);
479 // If enum variants have discriminants, try to vertically align those,
480 // provided the discrims are not shifted too much to the right
481 let align_threshold: usize = self.config.enum_discrim_align_threshold();
482 let discr_ident_lens: Vec<usize> = enum_def
485 .filter(|var| var.disr_expr.is_some())
486 .map(|var| rewrite_ident(&self.get_context(), var.ident).len())
488 // cut the list at the point of longest discrim shorter than the threshold
489 // All of the discrims under the threshold will get padded, and all above - left as is.
490 let pad_discrim_ident_to = *discr_ident_lens
492 .filter(|&l| *l <= align_threshold)
496 let itemize_list_with = |one_line_width: usize| {
498 self.snippet_provider,
499 enum_def.variants.iter(),
503 if !f.attrs.is_empty() {
510 |f| self.format_variant(f, one_line_width, pad_discrim_ident_to),
517 let mut items: Vec<_> = itemize_list_with(self.config.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::new(shape, self.config)
528 .trailing_separator(self.config.trailing_comma())
529 .preserve_newline(true);
531 let list = write_list(&items, &fmt)?;
532 result.push_str(&list);
533 result.push_str(&original_offset.to_string_with_newline(self.config));
538 // Variant of an enum.
541 field: &ast::Variant,
542 one_line_width: usize,
543 pad_discrim_ident_to: usize,
544 ) -> Option<String> {
545 if contains_skip(&field.attrs) {
546 let lo = field.attrs[0].span.lo();
547 let span = mk_sp(lo, field.span.hi());
548 return Some(self.snippet(span).to_owned());
551 let context = self.get_context();
553 let shape = self.shape().sub_width(1)?;
554 let attrs_str = field.attrs.rewrite(&context, shape)?;
558 .map_or(field.span.lo(), |attr| attr.span.hi());
559 let span = mk_sp(lo, field.span.lo());
561 let variant_body = match field.data {
562 ast::VariantData::Tuple(..) | ast::VariantData::Struct(..) => format_struct(
564 &StructParts::from_variant(field),
566 Some(one_line_width),
568 ast::VariantData::Unit(..) => rewrite_ident(&context, field.ident).to_owned(),
571 let variant_body = if let Some(ref expr) = field.disr_expr {
572 let lhs = format!("{:1$} =", variant_body, pad_discrim_ident_to);
573 let ex = &*expr.value;
574 rewrite_assign_rhs_with(
579 &RhsAssignKind::Expr(&ex.kind, ex.span),
580 RhsTactics::AllowOverflow,
586 combine_strs_with_missing_comments(&context, &attrs_str, &variant_body, span, shape, false)
589 fn visit_impl_items(&mut self, items: &[ptr::P<ast::AssocItem>]) {
590 if self.get_context().config.reorder_impl_items() {
591 type TyOpt = Option<ptr::P<ast::Ty>>;
592 use crate::ast::AssocItemKind::*;
593 let is_type = |ty: &TyOpt| opaque_ty(ty).is_none();
594 let is_opaque = |ty: &TyOpt| opaque_ty(ty).is_some();
595 let both_type = |l: &TyOpt, r: &TyOpt| is_type(l) && is_type(r);
596 let both_opaque = |l: &TyOpt, r: &TyOpt| is_opaque(l) && is_opaque(r);
597 let need_empty_line = |a: &ast::AssocItemKind, b: &ast::AssocItemKind| match (a, b) {
598 (TyAlias(lty), TyAlias(rty))
599 if both_type(<y.ty, &rty.ty) || both_opaque(<y.ty, &rty.ty) =>
603 (Const(..), Const(..)) => false,
607 // Create visitor for each items, then reorder them.
608 let mut buffer = vec![];
610 self.visit_impl_item(item);
611 buffer.push((self.buffer.clone(), item.clone()));
615 buffer.sort_by(|(_, a), (_, b)| match (&a.kind, &b.kind) {
616 (TyAlias(lty), TyAlias(rty))
617 if both_type(<y.ty, &rty.ty) || both_opaque(<y.ty, &rty.ty) =>
619 a.ident.as_str().cmp(b.ident.as_str())
621 (Const(..), Const(..)) | (MacCall(..), MacCall(..)) => {
622 a.ident.as_str().cmp(b.ident.as_str())
624 (Fn(..), Fn(..)) => a.span.lo().cmp(&b.span.lo()),
625 (TyAlias(ty), _) if is_type(&ty.ty) => Ordering::Less,
626 (_, TyAlias(ty)) if is_type(&ty.ty) => Ordering::Greater,
627 (TyAlias(..), _) => Ordering::Less,
628 (_, TyAlias(..)) => Ordering::Greater,
629 (Const(..), _) => Ordering::Less,
630 (_, Const(..)) => Ordering::Greater,
631 (MacCall(..), _) => Ordering::Less,
632 (_, MacCall(..)) => Ordering::Greater,
634 let mut prev_kind = None;
635 for (buf, item) in buffer {
636 // Make sure that there are at least a single empty line between
637 // different impl items.
640 .map_or(false, |prev_kind| need_empty_line(prev_kind, &item.kind))
644 let indent_str = self.block_indent.to_string_with_newline(self.config);
645 self.push_str(&indent_str);
646 self.push_str(buf.trim());
647 prev_kind = Some(item.kind.clone());
651 self.visit_impl_item(item);
657 pub(crate) fn format_impl(
658 context: &RewriteContext<'_>,
662 ) -> Option<String> {
669 let mut result = String::with_capacity(128);
670 let ref_and_type = format_impl_ref_and_type(context, item, iimpl, offset)?;
671 let sep = offset.to_string_with_newline(context.config);
672 result.push_str(&ref_and_type);
674 let where_budget = if result.contains('\n') {
675 context.config.max_width()
677 context.budget(last_line_width(&result))
680 let mut option = WhereClauseOption::snuggled(&ref_and_type);
681 let snippet = context.snippet(item.span);
682 let open_pos = snippet.find_uncommented("{")? + 1;
683 if !contains_comment(&snippet[open_pos..])
685 && generics.where_clause.predicates.len() == 1
686 && !result.contains('\n')
688 option.suppress_comma();
690 option.allow_single_line();
693 let missing_span = mk_sp(self_ty.span.hi(), item.span.hi());
694 let where_span_end = context.snippet_provider.opt_span_before(missing_span, "{");
695 let where_clause_str = rewrite_where_clause(
697 &generics.where_clause,
698 context.config.brace_style(),
699 Shape::legacy(where_budget, offset.block_only()),
707 // If there is no where-clause, we may have missing comments between the trait name and
708 // the opening brace.
709 if generics.where_clause.predicates.is_empty() {
710 if let Some(hi) = where_span_end {
711 match recover_missing_comment_in_span(
712 mk_sp(self_ty.span.hi(), hi),
713 Shape::indented(offset, context.config),
715 last_line_width(&result),
717 Some(ref missing_comment) if !missing_comment.is_empty() => {
718 result.push_str(missing_comment);
725 if is_impl_single_line(context, items.as_slice(), &result, &where_clause_str, item)? {
726 result.push_str(&where_clause_str);
727 if where_clause_str.contains('\n') || last_line_contains_single_line_comment(&result) {
728 // if the where_clause contains extra comments AND
729 // there is only one where-clause predicate
730 // recover the suppressed comma in single line where_clause formatting
731 if generics.where_clause.predicates.len() == 1 {
734 result.push_str(&format!("{}{{{}}}", sep, sep));
736 result.push_str(" {}");
741 result.push_str(&where_clause_str);
743 let need_newline = last_line_contains_single_line_comment(&result) || result.contains('\n');
744 match context.config.brace_style() {
745 _ if need_newline => result.push_str(&sep),
746 BraceStyle::AlwaysNextLine => result.push_str(&sep),
747 BraceStyle::PreferSameLine => result.push(' '),
748 BraceStyle::SameLineWhere => {
749 if !where_clause_str.is_empty() {
750 result.push_str(&sep);
758 // this is an impl body snippet(impl SampleImpl { /* here */ })
759 let lo = max(self_ty.span.hi(), generics.where_clause.span.hi());
760 let snippet = context.snippet(mk_sp(lo, item.span.hi()));
761 let open_pos = snippet.find_uncommented("{")? + 1;
763 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
764 let mut visitor = FmtVisitor::from_context(context);
765 let item_indent = offset.block_only().block_indent(context.config);
766 visitor.block_indent = item_indent;
767 visitor.last_pos = lo + BytePos(open_pos as u32);
769 visitor.visit_attrs(&item.attrs, ast::AttrStyle::Inner);
770 visitor.visit_impl_items(items);
772 visitor.format_missing(item.span.hi() - BytePos(1));
774 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
775 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
777 result.push_str(&inner_indent_str);
778 result.push_str(visitor.buffer.trim());
779 result.push_str(&outer_indent_str);
780 } else if need_newline || !context.config.empty_item_single_line() {
781 result.push_str(&sep);
789 fn is_impl_single_line(
790 context: &RewriteContext<'_>,
791 items: &[ptr::P<ast::AssocItem>],
793 where_clause_str: &str,
796 let snippet = context.snippet(item.span);
797 let open_pos = snippet.find_uncommented("{")? + 1;
800 context.config.empty_item_single_line()
802 && !result.contains('\n')
803 && result.len() + where_clause_str.len() <= context.config.max_width()
804 && !contains_comment(&snippet[open_pos..]),
808 fn format_impl_ref_and_type(
809 context: &RewriteContext<'_>,
813 ) -> Option<String> {
820 of_trait: ref trait_ref,
824 let mut result = String::with_capacity(128);
826 result.push_str(&format_visibility(context, &item.vis));
827 result.push_str(format_defaultness(defaultness));
828 result.push_str(format_unsafety(unsafety));
830 let shape = if context.config.version() == Version::Two {
831 Shape::indented(offset + last_line_width(&result), context.config)
833 generics_shape_from_config(
835 Shape::indented(offset + last_line_width(&result), context.config),
839 let generics_str = rewrite_generics(context, "impl", generics, shape)?;
840 result.push_str(&generics_str);
841 result.push_str(format_constness_right(constness));
843 let polarity_str = match polarity {
844 ast::ImplPolarity::Negative(_) => "!",
845 ast::ImplPolarity::Positive => "",
848 let polarity_overhead;
849 let trait_ref_overhead;
850 if let Some(ref trait_ref) = *trait_ref {
851 let result_len = last_line_width(&result);
852 result.push_str(&rewrite_trait_ref(
859 polarity_overhead = 0; // already written
860 trait_ref_overhead = " for".len();
862 polarity_overhead = polarity_str.len();
863 trait_ref_overhead = 0;
866 // Try to put the self type in a single line.
867 let curly_brace_overhead = if generics.where_clause.predicates.is_empty() {
868 // If there is no where-clause adapt budget for type formatting to take space and curly
869 // brace into account.
870 match context.config.brace_style() {
871 BraceStyle::AlwaysNextLine => 0,
878 last_line_width(&result) + polarity_overhead + trait_ref_overhead + curly_brace_overhead;
879 // 1 = space before the type.
880 let budget = context.budget(used_space + 1);
881 if let Some(self_ty_str) = self_ty.rewrite(context, Shape::legacy(budget, offset)) {
882 if !self_ty_str.contains('\n') {
883 if trait_ref.is_some() {
884 result.push_str(" for ");
887 result.push_str(polarity_str);
889 result.push_str(&self_ty_str);
894 // Couldn't fit the self type on a single line, put it on a new line.
896 // Add indentation of one additional tab.
897 let new_line_offset = offset.block_indent(context.config);
898 result.push_str(&new_line_offset.to_string(context.config));
899 if trait_ref.is_some() {
900 result.push_str("for ");
902 result.push_str(polarity_str);
904 let budget = context.budget(last_line_width(&result) + polarity_overhead);
905 let type_offset = match context.config.indent_style() {
906 IndentStyle::Visual => new_line_offset + trait_ref_overhead,
907 IndentStyle::Block => new_line_offset,
909 result.push_str(&*self_ty.rewrite(context, Shape::legacy(budget, type_offset))?);
913 fn rewrite_trait_ref(
914 context: &RewriteContext<'_>,
915 trait_ref: &ast::TraitRef,
919 ) -> Option<String> {
920 // 1 = space between generics and trait_ref
921 let used_space = 1 + polarity_str.len() + result_len;
922 let shape = Shape::indented(offset + used_space, context.config);
923 if let Some(trait_ref_str) = trait_ref.rewrite(context, shape) {
924 if !trait_ref_str.contains('\n') {
925 return Some(format!(" {}{}", polarity_str, trait_ref_str));
928 // We could not make enough space for trait_ref, so put it on new line.
929 let offset = offset.block_indent(context.config);
930 let shape = Shape::indented(offset, context.config);
931 let trait_ref_str = trait_ref.rewrite(context, shape)?;
934 offset.to_string_with_newline(context.config),
940 pub(crate) struct StructParts<'a> {
942 ident: symbol::Ident,
943 vis: &'a ast::Visibility,
944 def: &'a ast::VariantData,
945 generics: Option<&'a ast::Generics>,
949 impl<'a> StructParts<'a> {
950 fn format_header(&self, context: &RewriteContext<'_>, offset: Indent) -> String {
951 format_header(context, self.prefix, self.ident, self.vis, offset)
954 fn from_variant(variant: &'a ast::Variant) -> Self {
957 ident: variant.ident,
958 vis: &DEFAULT_VISIBILITY,
965 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
966 let (prefix, def, generics) = match item.kind {
967 ast::ItemKind::Struct(ref def, ref generics) => ("struct ", def, generics),
968 ast::ItemKind::Union(ref def, ref generics) => ("union ", def, generics),
976 generics: Some(generics),
983 context: &RewriteContext<'_>,
984 struct_parts: &StructParts<'_>,
986 one_line_width: Option<usize>,
987 ) -> Option<String> {
988 match *struct_parts.def {
989 ast::VariantData::Unit(..) => format_unit_struct(context, struct_parts, offset),
990 ast::VariantData::Tuple(ref fields, _) => {
991 format_tuple_struct(context, struct_parts, fields, offset)
993 ast::VariantData::Struct(ref fields, _) => {
994 format_struct_struct(context, struct_parts, fields, offset, one_line_width)
999 pub(crate) fn format_trait(
1000 context: &RewriteContext<'_>,
1003 ) -> Option<String> {
1004 if let ast::ItemKind::Trait(trait_kind) = &item.kind {
1012 let mut result = String::with_capacity(128);
1013 let header = format!(
1015 format_visibility(context, &item.vis),
1016 format_unsafety(unsafety),
1017 format_auto(is_auto),
1019 result.push_str(&header);
1021 let body_lo = context.snippet_provider.span_after(item.span, "{");
1023 let shape = Shape::indented(offset, context.config).offset_left(result.len())?;
1025 rewrite_generics(context, rewrite_ident(context, item.ident), generics, shape)?;
1026 result.push_str(&generics_str);
1028 // FIXME(#2055): rustfmt fails to format when there are comments between trait bounds.
1029 if !bounds.is_empty() {
1030 let ident_hi = context
1032 .span_after(item.span, item.ident.as_str());
1033 let bound_hi = bounds.last().unwrap().span().hi();
1034 let snippet = context.snippet(mk_sp(ident_hi, bound_hi));
1035 if contains_comment(snippet) {
1039 result = rewrite_assign_rhs_with(
1044 &RhsAssignKind::Bounds,
1045 RhsTactics::ForceNextLineWithoutIndent,
1049 // Rewrite where-clause.
1050 if !generics.where_clause.predicates.is_empty() {
1051 let where_on_new_line = context.config.indent_style() != IndentStyle::Block;
1053 let where_budget = context.budget(last_line_width(&result));
1054 let pos_before_where = if bounds.is_empty() {
1055 generics.where_clause.span.lo()
1057 bounds[bounds.len() - 1].span().hi()
1059 let option = WhereClauseOption::snuggled(&generics_str);
1060 let where_clause_str = rewrite_where_clause(
1062 &generics.where_clause,
1063 context.config.brace_style(),
1064 Shape::legacy(where_budget, offset.block_only()),
1071 // If the where-clause cannot fit on the same line,
1072 // put the where-clause on a new line
1073 if !where_clause_str.contains('\n')
1074 && last_line_width(&result) + where_clause_str.len() + offset.width()
1075 > context.config.comment_width()
1077 let width = offset.block_indent + context.config.tab_spaces() - 1;
1078 let where_indent = Indent::new(0, width);
1079 result.push_str(&where_indent.to_string_with_newline(context.config));
1081 result.push_str(&where_clause_str);
1083 let item_snippet = context.snippet(item.span);
1084 if let Some(lo) = item_snippet.find('/') {
1086 let comment_hi = body_lo - BytePos(1);
1087 let comment_lo = item.span.lo() + BytePos(lo as u32);
1088 if comment_lo < comment_hi {
1089 match recover_missing_comment_in_span(
1090 mk_sp(comment_lo, comment_hi),
1091 Shape::indented(offset, context.config),
1093 last_line_width(&result),
1095 Some(ref missing_comment) if !missing_comment.is_empty() => {
1096 result.push_str(missing_comment);
1104 let block_span = mk_sp(generics.where_clause.span.hi(), item.span.hi());
1105 let snippet = context.snippet(block_span);
1106 let open_pos = snippet.find_uncommented("{")? + 1;
1108 match context.config.brace_style() {
1109 _ if last_line_contains_single_line_comment(&result)
1110 || last_line_width(&result) + 2 > context.budget(offset.width()) =>
1112 result.push_str(&offset.to_string_with_newline(context.config));
1114 _ if context.config.empty_item_single_line()
1116 && !result.contains('\n')
1117 && !contains_comment(&snippet[open_pos..]) =>
1119 result.push_str(" {}");
1120 return Some(result);
1122 BraceStyle::AlwaysNextLine => {
1123 result.push_str(&offset.to_string_with_newline(context.config));
1125 BraceStyle::PreferSameLine => result.push(' '),
1126 BraceStyle::SameLineWhere => {
1127 if result.contains('\n')
1128 || (!generics.where_clause.predicates.is_empty() && !items.is_empty())
1130 result.push_str(&offset.to_string_with_newline(context.config));
1138 let outer_indent_str = offset.block_only().to_string_with_newline(context.config);
1140 if !items.is_empty() || contains_comment(&snippet[open_pos..]) {
1141 let mut visitor = FmtVisitor::from_context(context);
1142 visitor.block_indent = offset.block_only().block_indent(context.config);
1143 visitor.last_pos = block_span.lo() + BytePos(open_pos as u32);
1146 visitor.visit_trait_item(item);
1149 visitor.format_missing(item.span.hi() - BytePos(1));
1151 let inner_indent_str = visitor.block_indent.to_string_with_newline(context.config);
1153 result.push_str(&inner_indent_str);
1154 result.push_str(visitor.buffer.trim());
1155 result.push_str(&outer_indent_str);
1156 } else if result.contains('\n') {
1157 result.push_str(&outer_indent_str);
1167 pub(crate) struct TraitAliasBounds<'a> {
1168 generic_bounds: &'a ast::GenericBounds,
1169 generics: &'a ast::Generics,
1172 impl<'a> Rewrite for TraitAliasBounds<'a> {
1173 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1174 let generic_bounds_str = self.generic_bounds.rewrite(context, shape)?;
1176 let mut option = WhereClauseOption::new(true, WhereClauseSpace::None);
1177 option.allow_single_line();
1179 let where_str = rewrite_where_clause(
1181 &self.generics.where_clause,
1182 context.config.brace_style(),
1187 self.generics.where_clause.span.lo(),
1191 let fits_single_line = !generic_bounds_str.contains('\n')
1192 && !where_str.contains('\n')
1193 && generic_bounds_str.len() + where_str.len() < shape.width;
1194 let space = if generic_bounds_str.is_empty() || where_str.is_empty() {
1196 } else if fits_single_line {
1199 shape.indent.to_string_with_newline(context.config)
1202 Some(format!("{}{}{}", generic_bounds_str, space, where_str))
1206 pub(crate) fn format_trait_alias(
1207 context: &RewriteContext<'_>,
1208 ident: symbol::Ident,
1209 vis: &ast::Visibility,
1210 generics: &ast::Generics,
1211 generic_bounds: &ast::GenericBounds,
1213 ) -> Option<String> {
1214 let alias = rewrite_ident(context, ident);
1215 // 6 = "trait ", 2 = " ="
1216 let g_shape = shape.offset_left(6)?.sub_width(2)?;
1217 let generics_str = rewrite_generics(context, alias, generics, g_shape)?;
1218 let vis_str = format_visibility(context, vis);
1219 let lhs = format!("{}trait {} =", vis_str, generics_str);
1221 let trait_alias_bounds = TraitAliasBounds {
1228 &trait_alias_bounds,
1229 &RhsAssignKind::Bounds,
1230 shape.sub_width(1)?,
1235 fn format_unit_struct(
1236 context: &RewriteContext<'_>,
1237 p: &StructParts<'_>,
1239 ) -> Option<String> {
1240 let header_str = format_header(context, p.prefix, p.ident, p.vis, offset);
1241 let generics_str = if let Some(generics) = p.generics {
1242 let hi = context.snippet_provider.span_before(p.span, ";");
1246 context.config.brace_style(),
1249 // make a span that starts right after `struct Foo`
1250 mk_sp(p.ident.span.hi(), hi),
1251 last_line_width(&header_str),
1256 Some(format!("{}{};", header_str, generics_str))
1259 pub(crate) fn format_struct_struct(
1260 context: &RewriteContext<'_>,
1261 struct_parts: &StructParts<'_>,
1262 fields: &[ast::FieldDef],
1264 one_line_width: Option<usize>,
1265 ) -> Option<String> {
1266 let mut result = String::with_capacity(1024);
1267 let span = struct_parts.span;
1269 let header_str = struct_parts.format_header(context, offset);
1270 result.push_str(&header_str);
1272 let header_hi = struct_parts.ident.span.hi();
1273 let body_lo = context.snippet_provider.span_after(span, "{");
1275 let generics_str = match struct_parts.generics {
1276 Some(g) => format_generics(
1279 context.config.brace_style(),
1280 if fields.is_empty() {
1281 BracePos::ForceSameLine
1286 // make a span that starts right after `struct Foo`
1287 mk_sp(header_hi, body_lo),
1288 last_line_width(&result),
1291 // 3 = ` {}`, 2 = ` {`.
1292 let overhead = if fields.is_empty() { 3 } else { 2 };
1293 if (context.config.brace_style() == BraceStyle::AlwaysNextLine && !fields.is_empty())
1294 || context.config.max_width() < overhead + result.len()
1296 format!("\n{}{{", offset.block_only().to_string(context.config))
1303 let overhead = if fields.is_empty() { 1 } else { 0 };
1304 let total_width = result.len() + generics_str.len() + overhead;
1305 if !generics_str.is_empty()
1306 && !generics_str.contains('\n')
1307 && total_width > context.config.max_width()
1310 result.push_str(&offset.to_string(context.config));
1311 result.push_str(generics_str.trim_start());
1313 result.push_str(&generics_str);
1316 if fields.is_empty() {
1317 let inner_span = mk_sp(body_lo, span.hi() - BytePos(1));
1318 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "", "}");
1319 return Some(result);
1323 let one_line_budget = context.budget(result.len() + 3 + offset.width());
1324 let one_line_budget =
1325 one_line_width.map_or(0, |one_line_width| min(one_line_width, one_line_budget));
1327 let items_str = rewrite_with_alignment(
1330 Shape::indented(offset.block_indent(context.config), context.config).sub_width(1)?,
1331 mk_sp(body_lo, span.hi()),
1335 if !items_str.contains('\n')
1336 && !result.contains('\n')
1337 && items_str.len() <= one_line_budget
1338 && !last_line_contains_single_line_comment(&items_str)
1340 Some(format!("{} {} }}", result, items_str))
1346 .block_indent(context.config)
1347 .to_string(context.config),
1349 offset.to_string(context.config)
1354 fn get_bytepos_after_visibility(vis: &ast::Visibility, default_span: Span) -> BytePos {
1356 ast::VisibilityKind::Crate(..) | ast::VisibilityKind::Restricted { .. } => vis.span.hi(),
1357 _ => default_span.lo(),
1361 // Format tuple or struct without any fields. We need to make sure that the comments
1362 // inside the delimiters are preserved.
1363 fn format_empty_struct_or_tuple(
1364 context: &RewriteContext<'_>,
1367 result: &mut String,
1371 // 3 = " {}" or "();"
1372 let used_width = last_line_used_width(result, offset.width()) + 3;
1373 if used_width > context.config.max_width() {
1374 result.push_str(&offset.to_string_with_newline(context.config))
1376 result.push_str(opener);
1377 match rewrite_missing_comment(span, Shape::indented(offset, context.config), context) {
1378 Some(ref s) if s.is_empty() => (),
1380 if !is_single_line(s) || first_line_contains_single_line_comment(s) {
1381 let nested_indent_str = offset
1382 .block_indent(context.config)
1383 .to_string_with_newline(context.config);
1384 result.push_str(&nested_indent_str);
1387 if last_line_contains_single_line_comment(s) {
1388 result.push_str(&offset.to_string_with_newline(context.config));
1391 None => result.push_str(context.snippet(span)),
1393 result.push_str(closer);
1396 fn format_tuple_struct(
1397 context: &RewriteContext<'_>,
1398 struct_parts: &StructParts<'_>,
1399 fields: &[ast::FieldDef],
1401 ) -> Option<String> {
1402 let mut result = String::with_capacity(1024);
1403 let span = struct_parts.span;
1405 let header_str = struct_parts.format_header(context, offset);
1406 result.push_str(&header_str);
1408 let body_lo = if fields.is_empty() {
1409 let lo = get_bytepos_after_visibility(struct_parts.vis, span);
1412 .span_after(mk_sp(lo, span.hi()), "(")
1416 let body_hi = if fields.is_empty() {
1419 .span_after(mk_sp(body_lo, span.hi()), ")")
1421 // This is a dirty hack to work around a missing `)` from the span of the last field.
1422 let last_arg_span = fields[fields.len() - 1].span;
1425 .opt_span_after(mk_sp(last_arg_span.hi(), span.hi()), ")")
1426 .unwrap_or_else(|| last_arg_span.hi())
1429 let where_clause_str = match struct_parts.generics {
1431 let budget = context.budget(last_line_width(&header_str));
1432 let shape = Shape::legacy(budget, offset);
1433 let generics_str = rewrite_generics(context, "", generics, shape)?;
1434 result.push_str(&generics_str);
1436 let where_budget = context.budget(last_line_width(&result));
1437 let option = WhereClauseOption::new(true, WhereClauseSpace::Newline);
1438 rewrite_where_clause(
1440 &generics.where_clause,
1441 context.config.brace_style(),
1442 Shape::legacy(where_budget, offset.block_only()),
1450 None => "".to_owned(),
1453 if fields.is_empty() {
1454 let body_hi = context
1456 .span_before(mk_sp(body_lo, span.hi()), ")");
1457 let inner_span = mk_sp(body_lo, body_hi);
1458 format_empty_struct_or_tuple(context, inner_span, offset, &mut result, "(", ")");
1460 let shape = Shape::indented(offset, context.config).sub_width(1)?;
1461 let lo = if let Some(generics) = struct_parts.generics {
1464 struct_parts.ident.span.hi()
1466 result = overflow::rewrite_with_parens(
1471 mk_sp(lo, span.hi()),
1472 context.config.fn_call_width(),
1477 if !where_clause_str.is_empty()
1478 && !where_clause_str.contains('\n')
1479 && (result.contains('\n')
1480 || offset.block_indent + result.len() + where_clause_str.len() + 1
1481 > context.config.max_width())
1483 // We need to put the where-clause on a new line, but we didn't
1484 // know that earlier, so the where-clause will not be indented properly.
1487 &(offset.block_only() + (context.config.tab_spaces() - 1)).to_string(context.config),
1490 result.push_str(&where_clause_str);
1495 pub(crate) enum ItemVisitorKind<'a> {
1496 Item(&'a ast::Item),
1497 AssocTraitItem(&'a ast::AssocItem),
1498 AssocImplItem(&'a ast::AssocItem),
1499 ForeignItem(&'a ast::ForeignItem),
1502 struct TyAliasRewriteInfo<'c, 'g>(
1503 &'c RewriteContext<'c>,
1510 pub(crate) fn rewrite_type_alias<'a, 'b>(
1511 ty_alias_kind: &ast::TyAlias,
1512 context: &RewriteContext<'a>,
1514 visitor_kind: &ItemVisitorKind<'b>,
1516 ) -> Option<String> {
1517 use ItemVisitorKind::*;
1525 let ty_opt = ty.as_ref();
1526 let (ident, vis) = match visitor_kind {
1527 Item(i) => (i.ident, &i.vis),
1528 AssocTraitItem(i) | AssocImplItem(i) => (i.ident, &i.vis),
1529 ForeignItem(i) => (i.ident, &i.vis),
1531 let rw_info = &TyAliasRewriteInfo(context, indent, generics, ident, span);
1532 let op_ty = opaque_ty(ty);
1533 // Type Aliases are formatted slightly differently depending on the context
1534 // in which they appear, whether they are opaque, and whether they are associated.
1535 // https://rustc-dev-guide.rust-lang.org/opaque-types-type-alias-impl-trait.html
1536 // https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/items.md#type-aliases
1537 match (visitor_kind, &op_ty) {
1538 (Item(_) | AssocTraitItem(_) | ForeignItem(_), Some(op_bounds)) => {
1539 let op = OpaqueType { bounds: op_bounds };
1540 rewrite_ty(rw_info, Some(bounds), Some(&op), vis)
1542 (Item(_) | AssocTraitItem(_) | ForeignItem(_), None) => {
1543 rewrite_ty(rw_info, Some(bounds), ty_opt, vis)
1545 (AssocImplItem(_), _) => {
1546 let result = if let Some(op_bounds) = op_ty {
1547 let op = OpaqueType { bounds: op_bounds };
1548 rewrite_ty(rw_info, Some(bounds), Some(&op), &DEFAULT_VISIBILITY)
1550 rewrite_ty(rw_info, Some(bounds), ty_opt, vis)
1553 ast::Defaultness::Default(..) => Some(format!("default {}", result)),
1560 fn rewrite_ty<R: Rewrite>(
1561 rw_info: &TyAliasRewriteInfo<'_, '_>,
1562 generic_bounds_opt: Option<&ast::GenericBounds>,
1564 vis: &ast::Visibility,
1565 ) -> Option<String> {
1566 let mut result = String::with_capacity(128);
1567 let TyAliasRewriteInfo(context, indent, generics, ident, span) = *rw_info;
1568 result.push_str(&format!("{}type ", format_visibility(context, vis)));
1569 let ident_str = rewrite_ident(context, ident);
1571 if generics.params.is_empty() {
1572 result.push_str(ident_str)
1575 let g_shape = Shape::indented(indent, context.config)
1576 .offset_left(result.len())?
1578 let generics_str = rewrite_generics(context, ident_str, generics, g_shape)?;
1579 result.push_str(&generics_str);
1582 if let Some(bounds) = generic_bounds_opt {
1583 if !bounds.is_empty() {
1585 let shape = Shape::indented(indent, context.config).offset_left(result.len() + 2)?;
1586 let type_bounds = bounds.rewrite(context, shape).map(|s| format!(": {}", s))?;
1587 result.push_str(&type_bounds);
1591 let where_budget = context.budget(last_line_width(&result));
1592 let mut option = WhereClauseOption::snuggled(&result);
1594 option.suppress_comma();
1596 let where_clause_str = rewrite_where_clause(
1598 &generics.where_clause,
1599 context.config.brace_style(),
1600 Shape::legacy(where_budget, indent),
1607 result.push_str(&where_clause_str);
1609 if let Some(ty) = rhs {
1610 // If there's a where clause, add a newline before the assignment. Otherwise just add a
1612 let has_where = !generics.where_clause.predicates.is_empty();
1614 result.push_str(&indent.to_string_with_newline(context.config));
1619 let comment_span = context
1621 .opt_span_before(span, "=")
1622 .map(|op_lo| mk_sp(generics.where_clause.span.hi(), op_lo));
1624 let lhs = match comment_span {
1626 if contains_comment(context.snippet_provider.span_to_snippet(comment_span)?) =>
1628 let comment_shape = if has_where {
1629 Shape::indented(indent, context.config)
1631 Shape::indented(indent, context.config)
1632 .block_left(context.config.tab_spaces())?
1635 combine_strs_with_missing_comments(
1644 _ => format!("{}=", result),
1648 let shape = Shape::indented(indent, context.config).sub_width(1)?;
1649 rewrite_assign_rhs(context, lhs, &*ty, &RhsAssignKind::Ty, shape).map(|s| s + ";")
1651 Some(format!("{};", result))
1655 fn type_annotation_spacing(config: &Config) -> (&str, &str) {
1657 if config.space_before_colon() { " " } else { "" },
1658 if config.space_after_colon() { " " } else { "" },
1662 pub(crate) fn rewrite_struct_field_prefix(
1663 context: &RewriteContext<'_>,
1664 field: &ast::FieldDef,
1665 ) -> Option<String> {
1666 let vis = format_visibility(context, &field.vis);
1667 let type_annotation_spacing = type_annotation_spacing(context.config);
1668 Some(match field.ident {
1669 Some(name) => format!(
1672 rewrite_ident(context, name),
1673 type_annotation_spacing.0
1675 None => vis.to_string(),
1679 impl Rewrite for ast::FieldDef {
1680 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1681 rewrite_struct_field(context, self, shape, 0)
1685 pub(crate) fn rewrite_struct_field(
1686 context: &RewriteContext<'_>,
1687 field: &ast::FieldDef,
1689 lhs_max_width: usize,
1690 ) -> Option<String> {
1691 if contains_skip(&field.attrs) {
1692 return Some(context.snippet(field.span()).to_owned());
1695 let type_annotation_spacing = type_annotation_spacing(context.config);
1696 let prefix = rewrite_struct_field_prefix(context, field)?;
1698 let attrs_str = field.attrs.rewrite(context, shape)?;
1699 let attrs_extendable = field.ident.is_none() && is_attributes_extendable(&attrs_str);
1700 let missing_span = if field.attrs.is_empty() {
1701 mk_sp(field.span.lo(), field.span.lo())
1703 mk_sp(field.attrs.last().unwrap().span.hi(), field.span.lo())
1705 let mut spacing = String::from(if field.ident.is_some() {
1706 type_annotation_spacing.1
1710 // Try to put everything on a single line.
1711 let attr_prefix = combine_strs_with_missing_comments(
1719 let overhead = trimmed_last_line_width(&attr_prefix);
1720 let lhs_offset = lhs_max_width.saturating_sub(overhead);
1721 for _ in 0..lhs_offset {
1724 // In this extreme case we will be missing a space between an attribute and a field.
1725 if prefix.is_empty() && !attrs_str.is_empty() && attrs_extendable && spacing.is_empty() {
1729 .offset_left(overhead + spacing.len())
1730 .and_then(|ty_shape| field.ty.rewrite(context, ty_shape));
1731 if let Some(ref ty) = orig_ty {
1732 if !ty.contains('\n') {
1733 return Some(attr_prefix + &spacing + ty);
1737 let is_prefix_empty = prefix.is_empty();
1738 // We must use multiline. We are going to put attributes and a field on different lines.
1739 let field_str = rewrite_assign_rhs(context, prefix, &*field.ty, &RhsAssignKind::Ty, shape)?;
1740 // Remove a leading white-space from `rewrite_assign_rhs()` when rewriting a tuple struct.
1741 let field_str = if is_prefix_empty {
1742 field_str.trim_start()
1746 combine_strs_with_missing_comments(context, &attrs_str, field_str, missing_span, shape, false)
1749 pub(crate) struct StaticParts<'a> {
1751 vis: &'a ast::Visibility,
1752 ident: symbol::Ident,
1754 mutability: ast::Mutability,
1755 expr_opt: Option<&'a ptr::P<ast::Expr>>,
1756 defaultness: Option<ast::Defaultness>,
1760 impl<'a> StaticParts<'a> {
1761 pub(crate) fn from_item(item: &'a ast::Item) -> Self {
1762 let (defaultness, prefix, ty, mutability, expr) = match item.kind {
1763 ast::ItemKind::Static(ref ty, mutability, ref expr) => {
1764 (None, "static", ty, mutability, expr)
1766 ast::ItemKind::Const(defaultness, ref ty, ref expr) => {
1767 (Some(defaultness), "const", ty, ast::Mutability::Not, expr)
1769 _ => unreachable!(),
1777 expr_opt: expr.as_ref(),
1783 pub(crate) fn from_trait_item(ti: &'a ast::AssocItem) -> Self {
1784 let (defaultness, ty, expr_opt) = match ti.kind {
1785 ast::AssocItemKind::Const(defaultness, ref ty, ref expr_opt) => {
1786 (defaultness, ty, expr_opt)
1788 _ => unreachable!(),
1795 mutability: ast::Mutability::Not,
1796 expr_opt: expr_opt.as_ref(),
1797 defaultness: Some(defaultness),
1802 pub(crate) fn from_impl_item(ii: &'a ast::AssocItem) -> Self {
1803 let (defaultness, ty, expr) = match ii.kind {
1804 ast::AssocItemKind::Const(defaultness, ref ty, ref expr) => (defaultness, ty, expr),
1805 _ => unreachable!(),
1812 mutability: ast::Mutability::Not,
1813 expr_opt: expr.as_ref(),
1814 defaultness: Some(defaultness),
1821 context: &RewriteContext<'_>,
1822 static_parts: &StaticParts<'_>,
1824 ) -> Option<String> {
1825 let colon = colon_spaces(context.config);
1826 let mut prefix = format!(
1828 format_visibility(context, static_parts.vis),
1829 static_parts.defaultness.map_or("", format_defaultness),
1830 static_parts.prefix,
1831 format_mutability(static_parts.mutability),
1832 rewrite_ident(context, static_parts.ident),
1837 Shape::indented(offset.block_only(), context.config).offset_left(prefix.len() + 2)?;
1838 let ty_str = match static_parts.ty.rewrite(context, ty_shape) {
1839 Some(ty_str) => ty_str,
1841 if prefix.ends_with(' ') {
1844 let nested_indent = offset.block_indent(context.config);
1845 let nested_shape = Shape::indented(nested_indent, context.config);
1846 let ty_str = static_parts.ty.rewrite(context, nested_shape)?;
1849 nested_indent.to_string_with_newline(context.config),
1855 if let Some(expr) = static_parts.expr_opt {
1856 let comments_lo = context.snippet_provider.span_after(static_parts.span, "=");
1857 let expr_lo = expr.span.lo();
1858 let comments_span = mk_sp(comments_lo, expr_lo);
1860 let lhs = format!("{}{} =", prefix, ty_str);
1863 let remaining_width = context.budget(offset.block_indent + 1);
1864 rewrite_assign_rhs_with_comments(
1868 Shape::legacy(remaining_width, offset.block_only()),
1869 &RhsAssignKind::Expr(&expr.kind, expr.span),
1870 RhsTactics::Default,
1874 .and_then(|res| recover_comment_removed(res, static_parts.span, context))
1875 .map(|s| if s.ends_with(';') { s } else { s + ";" })
1877 Some(format!("{}{};", prefix, ty_str))
1881 // FIXME(calebcartwright) - This is a hack around a bug in the handling of TyKind::ImplTrait.
1882 // This should be removed once that bug is resolved, with the type alias formatting using the
1883 // defined Ty for the RHS directly.
1884 // https://github.com/rust-lang/rustfmt/issues/4373
1885 // https://github.com/rust-lang/rustfmt/issues/5027
1886 struct OpaqueType<'a> {
1887 bounds: &'a ast::GenericBounds,
1890 impl<'a> Rewrite for OpaqueType<'a> {
1891 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1892 let shape = shape.offset_left(5)?; // `impl `
1894 .rewrite(context, shape)
1895 .map(|s| format!("impl {}", s))
1899 impl Rewrite for ast::FnRetTy {
1900 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1902 ast::FnRetTy::Default(_) => Some(String::new()),
1903 ast::FnRetTy::Ty(ref ty) => {
1904 if context.config.version() == Version::One
1905 || context.config.indent_style() == IndentStyle::Visual
1907 let inner_width = shape.width.checked_sub(3)?;
1909 .rewrite(context, Shape::legacy(inner_width, shape.indent + 3))
1910 .map(|r| format!("-> {}", r));
1913 ty.rewrite(context, shape.offset_left(3)?)
1914 .map(|s| format!("-> {}", s))
1920 fn is_empty_infer(ty: &ast::Ty, pat_span: Span) -> bool {
1922 ast::TyKind::Infer => ty.span.hi() == pat_span.hi(),
1927 /// Recover any missing comments between the param and the type.
1931 /// A 2-len tuple with the comment before the colon in first position, and the comment after the
1932 /// colon in second position.
1933 fn get_missing_param_comments(
1934 context: &RewriteContext<'_>,
1938 ) -> (String, String) {
1939 let missing_comment_span = mk_sp(pat_span.hi(), ty_span.lo());
1941 let span_before_colon = {
1942 let missing_comment_span_hi = context
1944 .span_before(missing_comment_span, ":");
1945 mk_sp(pat_span.hi(), missing_comment_span_hi)
1947 let span_after_colon = {
1948 let missing_comment_span_lo = context
1950 .span_after(missing_comment_span, ":");
1951 mk_sp(missing_comment_span_lo, ty_span.lo())
1954 let comment_before_colon = rewrite_missing_comment(span_before_colon, shape, context)
1955 .filter(|comment| !comment.is_empty())
1956 .map_or(String::new(), |comment| format!(" {}", comment));
1957 let comment_after_colon = rewrite_missing_comment(span_after_colon, shape, context)
1958 .filter(|comment| !comment.is_empty())
1959 .map_or(String::new(), |comment| format!("{} ", comment));
1960 (comment_before_colon, comment_after_colon)
1963 impl Rewrite for ast::Param {
1964 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
1965 let param_attrs_result = self
1967 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1968 // N.B. Doc comments aren't typically valid syntax, but could appear
1969 // in the presence of certain macros - https://github.com/rust-lang/rustfmt/issues/4936
1970 let (span, has_multiple_attr_lines, has_doc_comments) = if !self.attrs.is_empty() {
1971 let num_attrs = self.attrs.len();
1973 mk_sp(self.attrs[num_attrs - 1].span.hi(), self.pat.span.lo()),
1974 param_attrs_result.contains('\n'),
1975 self.attrs.iter().any(|a| a.is_doc_comment()),
1978 (mk_sp(self.span.lo(), self.span.lo()), false, false)
1981 if let Some(ref explicit_self) = self.to_self() {
1982 rewrite_explicit_self(
1985 ¶m_attrs_result,
1988 has_multiple_attr_lines,
1990 } else if is_named_param(self) {
1991 let param_name = &self
1993 .rewrite(context, Shape::legacy(shape.width, shape.indent))?;
1994 let mut result = combine_strs_with_missing_comments(
1996 ¶m_attrs_result,
2000 !has_multiple_attr_lines && !has_doc_comments,
2003 if !is_empty_infer(&*self.ty, self.pat.span) {
2004 let (before_comment, after_comment) =
2005 get_missing_param_comments(context, self.pat.span, self.ty.span, shape);
2006 result.push_str(&before_comment);
2007 result.push_str(colon_spaces(context.config));
2008 result.push_str(&after_comment);
2009 let overhead = last_line_width(&result);
2010 let max_width = shape.width.checked_sub(overhead)?;
2011 if let Some(ty_str) = self
2013 .rewrite(context, Shape::legacy(max_width, shape.indent))
2015 result.push_str(&ty_str);
2017 result = combine_strs_with_missing_comments(
2019 &(param_attrs_result + &shape.to_string_with_newline(context.config)),
2023 !has_multiple_attr_lines,
2025 result.push_str(&before_comment);
2026 result.push_str(colon_spaces(context.config));
2027 result.push_str(&after_comment);
2028 let overhead = last_line_width(&result);
2029 let max_width = shape.width.checked_sub(overhead)?;
2032 .rewrite(context, Shape::legacy(max_width, shape.indent))?;
2033 result.push_str(&ty_str);
2039 self.ty.rewrite(context, shape)
2044 fn rewrite_explicit_self(
2045 context: &RewriteContext<'_>,
2046 explicit_self: &ast::ExplicitSelf,
2050 has_multiple_attr_lines: bool,
2051 ) -> Option<String> {
2052 match explicit_self.node {
2053 ast::SelfKind::Region(lt, m) => {
2054 let mut_str = format_mutability(m);
2057 let lifetime_str = l.rewrite(
2059 Shape::legacy(context.config.max_width(), Indent::empty()),
2061 Some(combine_strs_with_missing_comments(
2064 &format!("&{} {}self", lifetime_str, mut_str),
2067 !has_multiple_attr_lines,
2070 None => Some(combine_strs_with_missing_comments(
2073 &format!("&{}self", mut_str),
2076 !has_multiple_attr_lines,
2080 ast::SelfKind::Explicit(ref ty, mutability) => {
2081 let type_str = ty.rewrite(
2083 Shape::legacy(context.config.max_width(), Indent::empty()),
2086 Some(combine_strs_with_missing_comments(
2089 &format!("{}self: {}", format_mutability(mutability), type_str),
2092 !has_multiple_attr_lines,
2095 ast::SelfKind::Value(mutability) => Some(combine_strs_with_missing_comments(
2098 &format!("{}self", format_mutability(mutability)),
2101 !has_multiple_attr_lines,
2106 pub(crate) fn span_lo_for_param(param: &ast::Param) -> BytePos {
2107 if param.attrs.is_empty() {
2108 if is_named_param(param) {
2114 param.attrs[0].span.lo()
2118 pub(crate) fn span_hi_for_param(context: &RewriteContext<'_>, param: &ast::Param) -> BytePos {
2119 match param.ty.kind {
2120 ast::TyKind::Infer if context.snippet(param.ty.span) == "_" => param.ty.span.hi(),
2121 ast::TyKind::Infer if is_named_param(param) => param.pat.span.hi(),
2122 _ => param.ty.span.hi(),
2126 pub(crate) fn is_named_param(param: &ast::Param) -> bool {
2127 if let ast::PatKind::Ident(_, ident, _) = param.pat.kind {
2128 ident.name != symbol::kw::Empty
2134 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
2135 pub(crate) enum FnBraceStyle {
2141 // Return type is (result, force_new_line_for_brace)
2143 context: &RewriteContext<'_>,
2145 ident: symbol::Ident,
2148 fn_brace_style: FnBraceStyle,
2149 ) -> Option<(String, bool, bool)> {
2150 let mut force_new_line_for_brace = false;
2152 let where_clause = &fn_sig.generics.where_clause;
2154 let mut result = String::with_capacity(1024);
2155 result.push_str(&fn_sig.to_str(context));
2158 result.push_str("fn ");
2161 let overhead = if let FnBraceStyle::SameLine = fn_brace_style {
2168 let used_width = last_line_used_width(&result, indent.width());
2169 let one_line_budget = context.budget(used_width + overhead);
2171 width: one_line_budget,
2175 let fd = fn_sig.decl;
2176 let generics_str = rewrite_generics(
2178 rewrite_ident(context, ident),
2182 result.push_str(&generics_str);
2184 let snuggle_angle_bracket = generics_str
2187 .map_or(false, |l| l.trim_start().len() == 1);
2189 // Note that the width and indent don't really matter, we'll re-layout the
2190 // return type later anyway.
2193 .rewrite(context, Shape::indented(indent, context.config))?;
2195 let multi_line_ret_str = ret_str.contains('\n');
2196 let ret_str_len = if multi_line_ret_str { 0 } else { ret_str.len() };
2199 let (one_line_budget, multi_line_budget, mut param_indent) = compute_budgets_for_params(
2209 "rewrite_fn_base: one_line_budget: {}, multi_line_budget: {}, param_indent: {:?}",
2210 one_line_budget, multi_line_budget, param_indent
2214 // Check if vertical layout was forced.
2215 if one_line_budget == 0
2216 && !snuggle_angle_bracket
2217 && context.config.indent_style() == IndentStyle::Visual
2219 result.push_str(¶m_indent.to_string_with_newline(context.config));
2222 let params_end = if fd.inputs.is_empty() {
2225 .span_after(mk_sp(fn_sig.generics.span.hi(), span.hi()), ")")
2227 let last_span = mk_sp(fd.inputs[fd.inputs.len() - 1].span().hi(), span.hi());
2228 context.snippet_provider.span_after(last_span, ")")
2230 let params_span = mk_sp(
2233 .span_after(mk_sp(fn_sig.generics.span.hi(), span.hi()), "("),
2236 let param_str = rewrite_params(
2247 let put_params_in_block = match context.config.indent_style() {
2248 IndentStyle::Block => param_str.contains('\n') || param_str.len() > one_line_budget,
2250 } && !fd.inputs.is_empty();
2252 let mut params_last_line_contains_comment = false;
2253 let mut no_params_and_over_max_width = false;
2255 if put_params_in_block {
2256 param_indent = indent.block_indent(context.config);
2257 result.push_str(¶m_indent.to_string_with_newline(context.config));
2258 result.push_str(¶m_str);
2259 result.push_str(&indent.to_string_with_newline(context.config));
2262 result.push_str(¶m_str);
2263 let used_width = last_line_used_width(&result, indent.width()) + first_line_width(&ret_str);
2264 // Put the closing brace on the next line if it overflows the max width.
2266 let closing_paren_overflow_max_width =
2267 fd.inputs.is_empty() && used_width + 1 > context.config.max_width();
2268 // If the last line of params contains comment, we cannot put the closing paren
2269 // on the same line.
2270 params_last_line_contains_comment = param_str
2273 .map_or(false, |last_line| last_line.contains("//"));
2275 if context.config.version() == Version::Two {
2276 if closing_paren_overflow_max_width {
2278 result.push_str(&indent.to_string_with_newline(context.config));
2279 no_params_and_over_max_width = true;
2280 } else if params_last_line_contains_comment {
2281 result.push_str(&indent.to_string_with_newline(context.config));
2283 no_params_and_over_max_width = true;
2288 if closing_paren_overflow_max_width || params_last_line_contains_comment {
2289 result.push_str(&indent.to_string_with_newline(context.config));
2296 if let ast::FnRetTy::Ty(..) = fd.output {
2297 let ret_should_indent = match context.config.indent_style() {
2298 // If our params are block layout then we surely must have space.
2299 IndentStyle::Block if put_params_in_block || fd.inputs.is_empty() => false,
2300 _ if params_last_line_contains_comment => false,
2301 _ if result.contains('\n') || multi_line_ret_str => true,
2303 // If the return type would push over the max width, then put the return type on
2304 // a new line. With the +1 for the signature length an additional space between
2305 // the closing parenthesis of the param and the arrow '->' is considered.
2306 let mut sig_length = result.len() + indent.width() + ret_str_len + 1;
2308 // If there is no where-clause, take into account the space after the return type
2310 if where_clause.predicates.is_empty() {
2314 sig_length > context.config.max_width()
2317 let ret_shape = if ret_should_indent {
2318 if context.config.version() == Version::One
2319 || context.config.indent_style() == IndentStyle::Visual
2321 let indent = if param_str.is_empty() {
2322 // Aligning with non-existent params looks silly.
2323 force_new_line_for_brace = true;
2326 // FIXME: we might want to check that using the param indent
2327 // doesn't blow our budget, and if it does, then fallback to
2328 // the where-clause indent.
2332 result.push_str(&indent.to_string_with_newline(context.config));
2333 Shape::indented(indent, context.config)
2335 let mut ret_shape = Shape::indented(indent, context.config);
2336 if param_str.is_empty() {
2337 // Aligning with non-existent params looks silly.
2338 force_new_line_for_brace = true;
2339 ret_shape = if context.use_block_indent() {
2340 ret_shape.offset_left(4).unwrap_or(ret_shape)
2342 ret_shape.indent = ret_shape.indent + 4;
2347 result.push_str(&ret_shape.indent.to_string_with_newline(context.config));
2351 if context.config.version() == Version::Two {
2352 if !param_str.is_empty() || !no_params_and_over_max_width {
2359 let ret_shape = Shape::indented(indent, context.config);
2361 .offset_left(last_line_width(&result))
2362 .unwrap_or(ret_shape)
2365 if multi_line_ret_str || ret_should_indent {
2366 // Now that we know the proper indent and width, we need to
2367 // re-layout the return type.
2368 let ret_str = fd.output.rewrite(context, ret_shape)?;
2369 result.push_str(&ret_str);
2371 result.push_str(&ret_str);
2374 // Comment between return type and the end of the decl.
2375 let snippet_lo = fd.output.span().hi();
2376 if where_clause.predicates.is_empty() {
2377 let snippet_hi = span.hi();
2378 let snippet = context.snippet(mk_sp(snippet_lo, snippet_hi));
2379 // Try to preserve the layout of the original snippet.
2380 let original_starts_with_newline = snippet
2382 .map_or(false, |i| starts_with_newline(&snippet[i..]));
2383 let original_ends_with_newline = snippet
2384 .rfind(|c| c != ' ')
2385 .map_or(false, |i| snippet[i..].ends_with('\n'));
2386 let snippet = snippet.trim();
2387 if !snippet.is_empty() {
2388 result.push(if original_starts_with_newline {
2393 result.push_str(snippet);
2394 if original_ends_with_newline {
2395 force_new_line_for_brace = true;
2401 let pos_before_where = match fd.output {
2402 ast::FnRetTy::Default(..) => params_span.hi(),
2403 ast::FnRetTy::Ty(ref ty) => ty.span.hi(),
2406 let is_params_multi_lined = param_str.contains('\n');
2408 let space = if put_params_in_block && ret_str.is_empty() {
2409 WhereClauseSpace::Space
2411 WhereClauseSpace::Newline
2413 let mut option = WhereClauseOption::new(fn_brace_style == FnBraceStyle::None, space);
2414 if is_params_multi_lined {
2415 option.veto_single_line();
2417 let where_clause_str = rewrite_where_clause(
2420 context.config.brace_style(),
2421 Shape::indented(indent, context.config),
2428 // If there are neither where-clause nor return type, we may be missing comments between
2430 if where_clause_str.is_empty() {
2431 if let ast::FnRetTy::Default(ret_span) = fd.output {
2432 match recover_missing_comment_in_span(
2433 mk_sp(params_span.hi(), ret_span.hi()),
2436 last_line_width(&result),
2438 Some(ref missing_comment) if !missing_comment.is_empty() => {
2439 result.push_str(missing_comment);
2440 force_new_line_for_brace = true;
2447 result.push_str(&where_clause_str);
2449 let ends_with_comment = last_line_contains_single_line_comment(&result);
2450 force_new_line_for_brace |= ends_with_comment;
2451 force_new_line_for_brace |=
2452 is_params_multi_lined && context.config.where_single_line() && !where_clause_str.is_empty();
2453 Some((result, ends_with_comment, force_new_line_for_brace))
2456 /// Kind of spaces to put before `where`.
2457 #[derive(Copy, Clone)]
2458 enum WhereClauseSpace {
2467 #[derive(Copy, Clone)]
2468 struct WhereClauseOption {
2469 suppress_comma: bool, // Force no trailing comma
2470 snuggle: WhereClauseSpace,
2471 allow_single_line: bool, // Try single line where-clause instead of vertical layout
2472 veto_single_line: bool, // Disallow a single-line where-clause.
2475 impl WhereClauseOption {
2476 fn new(suppress_comma: bool, snuggle: WhereClauseSpace) -> WhereClauseOption {
2480 allow_single_line: false,
2481 veto_single_line: false,
2485 fn snuggled(current: &str) -> WhereClauseOption {
2487 suppress_comma: false,
2488 snuggle: if last_line_width(current) == 1 {
2489 WhereClauseSpace::Space
2491 WhereClauseSpace::Newline
2493 allow_single_line: false,
2494 veto_single_line: false,
2498 fn suppress_comma(&mut self) {
2499 self.suppress_comma = true
2502 fn allow_single_line(&mut self) {
2503 self.allow_single_line = true
2506 fn snuggle(&mut self) {
2507 self.snuggle = WhereClauseSpace::Space
2510 fn veto_single_line(&mut self) {
2511 self.veto_single_line = true;
2516 context: &RewriteContext<'_>,
2517 params: &[ast::Param],
2518 one_line_budget: usize,
2519 multi_line_budget: usize,
2521 param_indent: Indent,
2524 ) -> Option<String> {
2525 if params.is_empty() {
2526 let comment = context
2530 span.hi() - BytePos(1),
2533 return Some(comment.to_owned());
2535 let param_items: Vec<_> = itemize_list(
2536 context.snippet_provider,
2540 |param| span_lo_for_param(param),
2541 |param| param.ty.span.hi(),
2544 .rewrite(context, Shape::legacy(multi_line_budget, param_indent))
2545 .or_else(|| Some(context.snippet(param.span()).to_owned()))
2553 let tactic = definitive_tactic(
2558 .to_list_tactic(param_items.len()),
2562 let budget = match tactic {
2563 DefinitiveListTactic::Horizontal => one_line_budget,
2564 _ => multi_line_budget,
2566 let indent = match context.config.indent_style() {
2567 IndentStyle::Block => indent.block_indent(context.config),
2568 IndentStyle::Visual => param_indent,
2570 let trailing_separator = if variadic {
2571 SeparatorTactic::Never
2573 match context.config.indent_style() {
2574 IndentStyle::Block => context.config.trailing_comma(),
2575 IndentStyle::Visual => SeparatorTactic::Never,
2578 let fmt = ListFormatting::new(Shape::legacy(budget, indent), context.config)
2580 .trailing_separator(trailing_separator)
2581 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2582 .preserve_newline(true);
2583 write_list(¶m_items, &fmt)
2586 fn compute_budgets_for_params(
2587 context: &RewriteContext<'_>,
2591 fn_brace_style: FnBraceStyle,
2592 force_vertical_layout: bool,
2593 ) -> Option<(usize, usize, Indent)> {
2595 "compute_budgets_for_params {} {:?}, {}, {:?}",
2601 // Try keeping everything on the same line.
2602 if !result.contains('\n') && !force_vertical_layout {
2603 // 2 = `()`, 3 = `() `, space is before ret_string.
2604 let overhead = if ret_str_len == 0 { 2 } else { 3 };
2605 let mut used_space = indent.width() + result.len() + ret_str_len + overhead;
2606 match fn_brace_style {
2607 FnBraceStyle::None => used_space += 1, // 1 = `;`
2608 FnBraceStyle::SameLine => used_space += 2, // 2 = `{}`
2609 FnBraceStyle::NextLine => (),
2611 let one_line_budget = context.budget(used_space);
2613 if one_line_budget > 0 {
2615 let (indent, multi_line_budget) = match context.config.indent_style() {
2616 IndentStyle::Block => {
2617 let indent = indent.block_indent(context.config);
2618 (indent, context.budget(indent.width() + 1))
2620 IndentStyle::Visual => {
2621 let indent = indent + result.len() + 1;
2622 let multi_line_overhead = match fn_brace_style {
2623 FnBraceStyle::SameLine => 4,
2626 (indent, context.budget(multi_line_overhead))
2630 return Some((one_line_budget, multi_line_budget, indent));
2634 // Didn't work. we must force vertical layout and put params on a newline.
2635 let new_indent = indent.block_indent(context.config);
2636 let used_space = match context.config.indent_style() {
2638 IndentStyle::Block => new_indent.width() + 1,
2639 // Account for `)` and possibly ` {`.
2640 IndentStyle::Visual => new_indent.width() + if ret_str_len == 0 { 1 } else { 3 },
2642 Some((0, context.budget(used_space), new_indent))
2645 fn newline_for_brace(config: &Config, where_clause: &ast::WhereClause) -> FnBraceStyle {
2646 let predicate_count = where_clause.predicates.len();
2648 if config.where_single_line() && predicate_count == 1 {
2649 return FnBraceStyle::SameLine;
2651 let brace_style = config.brace_style();
2653 let use_next_line = brace_style == BraceStyle::AlwaysNextLine
2654 || (brace_style == BraceStyle::SameLineWhere && predicate_count > 0);
2656 FnBraceStyle::NextLine
2658 FnBraceStyle::SameLine
2662 fn rewrite_generics(
2663 context: &RewriteContext<'_>,
2665 generics: &ast::Generics,
2667 ) -> Option<String> {
2668 // FIXME: convert bounds to where-clauses where they get too big or if
2669 // there is a where-clause at all.
2671 if generics.params.is_empty() {
2672 return Some(ident.to_owned());
2675 let params = generics.params.iter();
2676 overflow::rewrite_with_angle_brackets(context, ident, params, shape, generics.span)
2679 fn generics_shape_from_config(config: &Config, shape: Shape, offset: usize) -> Option<Shape> {
2680 match config.indent_style() {
2681 IndentStyle::Visual => shape.visual_indent(1 + offset).sub_width(offset + 2),
2682 IndentStyle::Block => {
2686 .block_indent(config.tab_spaces())
2687 .with_max_width(config)
2693 fn rewrite_where_clause_rfc_style(
2694 context: &RewriteContext<'_>,
2695 where_clause: &ast::WhereClause,
2698 span_end: Option<BytePos>,
2699 span_end_before_where: BytePos,
2700 where_clause_option: WhereClauseOption,
2701 ) -> Option<String> {
2702 let (where_keyword, allow_single_line) = rewrite_where_keyword(
2706 span_end_before_where,
2707 where_clause_option,
2711 let clause_shape = shape
2713 .with_max_width(context.config)
2714 .block_left(context.config.tab_spaces())?
2716 let force_single_line = context.config.where_single_line()
2717 && where_clause.predicates.len() == 1
2718 && !where_clause_option.veto_single_line;
2720 let preds_str = rewrite_bounds_on_where_clause(
2726 where_clause_option,
2732 if allow_single_line && !preds_str.contains('\n') && 6 + preds_str.len() <= shape.width
2733 || force_single_line
2737 clause_shape.indent.to_string_with_newline(context.config)
2740 Some(format!("{}{}{}", where_keyword, clause_sep, preds_str))
2743 /// Rewrite `where` and comment around it.
2744 fn rewrite_where_keyword(
2745 context: &RewriteContext<'_>,
2746 where_clause: &ast::WhereClause,
2748 span_end_before_where: BytePos,
2749 where_clause_option: WhereClauseOption,
2750 ) -> Option<(String, bool)> {
2751 let block_shape = shape.block().with_max_width(context.config);
2753 let clause_shape = block_shape
2754 .block_left(context.config.tab_spaces())?
2757 let comment_separator = |comment: &str, shape: Shape| {
2758 if comment.is_empty() {
2761 shape.indent.to_string_with_newline(context.config)
2765 let (span_before, span_after) =
2766 missing_span_before_after_where(span_end_before_where, where_clause);
2767 let (comment_before, comment_after) =
2768 rewrite_comments_before_after_where(context, span_before, span_after, shape)?;
2770 let starting_newline = match where_clause_option.snuggle {
2771 WhereClauseSpace::Space if comment_before.is_empty() => Cow::from(" "),
2772 WhereClauseSpace::None => Cow::from(""),
2773 _ => block_shape.indent.to_string_with_newline(context.config),
2776 let newline_before_where = comment_separator(&comment_before, shape);
2777 let newline_after_where = comment_separator(&comment_after, clause_shape);
2778 let result = format!(
2780 starting_newline, comment_before, newline_before_where, newline_after_where, comment_after
2782 let allow_single_line = where_clause_option.allow_single_line
2783 && comment_before.is_empty()
2784 && comment_after.is_empty();
2786 Some((result, allow_single_line))
2789 /// Rewrite bounds on a where clause.
2790 fn rewrite_bounds_on_where_clause(
2791 context: &RewriteContext<'_>,
2792 where_clause: &ast::WhereClause,
2795 span_end: Option<BytePos>,
2796 where_clause_option: WhereClauseOption,
2797 force_single_line: bool,
2798 ) -> Option<String> {
2799 let span_start = where_clause.predicates[0].span().lo();
2800 // If we don't have the start of the next span, then use the end of the
2801 // predicates, but that means we miss comments.
2802 let len = where_clause.predicates.len();
2803 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2804 let span_end = span_end.unwrap_or(end_of_preds);
2805 let items = itemize_list(
2806 context.snippet_provider,
2807 where_clause.predicates.iter(),
2810 |pred| pred.span().lo(),
2811 |pred| pred.span().hi(),
2812 |pred| pred.rewrite(context, shape),
2817 let comma_tactic = if where_clause_option.suppress_comma || force_single_line {
2818 SeparatorTactic::Never
2820 context.config.trailing_comma()
2823 // shape should be vertical only and only if we have `force_single_line` option enabled
2824 // and the number of items of the where-clause is equal to 1
2825 let shape_tactic = if force_single_line {
2826 DefinitiveListTactic::Horizontal
2828 DefinitiveListTactic::Vertical
2831 let fmt = ListFormatting::new(shape, context.config)
2832 .tactic(shape_tactic)
2833 .trailing_separator(comma_tactic)
2834 .preserve_newline(true);
2835 write_list(&items.collect::<Vec<_>>(), &fmt)
2838 fn rewrite_where_clause(
2839 context: &RewriteContext<'_>,
2840 where_clause: &ast::WhereClause,
2841 brace_style: BraceStyle,
2845 span_end: Option<BytePos>,
2846 span_end_before_where: BytePos,
2847 where_clause_option: WhereClauseOption,
2848 ) -> Option<String> {
2849 if where_clause.predicates.is_empty() {
2850 return Some(String::new());
2853 if context.config.indent_style() == IndentStyle::Block {
2854 return rewrite_where_clause_rfc_style(
2860 span_end_before_where,
2861 where_clause_option,
2865 let extra_indent = Indent::new(context.config.tab_spaces(), 0);
2867 let offset = match context.config.indent_style() {
2868 IndentStyle::Block => shape.indent + extra_indent.block_indent(context.config),
2869 // 6 = "where ".len()
2870 IndentStyle::Visual => shape.indent + extra_indent + 6,
2872 // FIXME: if indent_style != Visual, then the budgets below might
2873 // be out by a char or two.
2875 let budget = context.config.max_width() - offset.width();
2876 let span_start = where_clause.predicates[0].span().lo();
2877 // If we don't have the start of the next span, then use the end of the
2878 // predicates, but that means we miss comments.
2879 let len = where_clause.predicates.len();
2880 let end_of_preds = where_clause.predicates[len - 1].span().hi();
2881 let span_end = span_end.unwrap_or(end_of_preds);
2882 let items = itemize_list(
2883 context.snippet_provider,
2884 where_clause.predicates.iter(),
2887 |pred| pred.span().lo(),
2888 |pred| pred.span().hi(),
2889 |pred| pred.rewrite(context, Shape::legacy(budget, offset)),
2894 let item_vec = items.collect::<Vec<_>>();
2895 // FIXME: we don't need to collect here
2896 let tactic = definitive_tactic(&item_vec, ListTactic::Vertical, Separator::Comma, budget);
2898 let mut comma_tactic = context.config.trailing_comma();
2899 // Kind of a hack because we don't usually have trailing commas in where-clauses.
2900 if comma_tactic == SeparatorTactic::Vertical || where_clause_option.suppress_comma {
2901 comma_tactic = SeparatorTactic::Never;
2904 let fmt = ListFormatting::new(Shape::legacy(budget, offset), context.config)
2906 .trailing_separator(comma_tactic)
2907 .ends_with_newline(tactic.ends_with_newline(context.config.indent_style()))
2908 .preserve_newline(true);
2909 let preds_str = write_list(&item_vec, &fmt)?;
2911 let end_length = if terminator == "{" {
2912 // If the brace is on the next line we don't need to count it otherwise it needs two
2915 BraceStyle::AlwaysNextLine | BraceStyle::SameLineWhere => 0,
2916 BraceStyle::PreferSameLine => 2,
2918 } else if terminator == "=" {
2924 || preds_str.contains('\n')
2925 || shape.indent.width() + " where ".len() + preds_str.len() + end_length > shape.width
2929 (shape.indent + extra_indent).to_string(context.config),
2933 Some(format!(" where {}", preds_str))
2937 fn missing_span_before_after_where(
2938 before_item_span_end: BytePos,
2939 where_clause: &ast::WhereClause,
2941 let missing_span_before = mk_sp(before_item_span_end, where_clause.span.lo());
2943 let pos_after_where = where_clause.span.lo() + BytePos(5);
2944 let missing_span_after = mk_sp(pos_after_where, where_clause.predicates[0].span().lo());
2945 (missing_span_before, missing_span_after)
2948 fn rewrite_comments_before_after_where(
2949 context: &RewriteContext<'_>,
2950 span_before_where: Span,
2951 span_after_where: Span,
2953 ) -> Option<(String, String)> {
2954 let before_comment = rewrite_missing_comment(span_before_where, shape, context)?;
2955 let after_comment = rewrite_missing_comment(
2957 shape.block_indent(context.config.tab_spaces()),
2960 Some((before_comment, after_comment))
2964 context: &RewriteContext<'_>,
2966 ident: symbol::Ident,
2967 vis: &ast::Visibility,
2970 let mut result = String::with_capacity(128);
2971 let shape = Shape::indented(offset, context.config);
2973 result.push_str(format_visibility(context, vis).trim());
2975 // Check for a missing comment between the visibility and the item name.
2976 let after_vis = vis.span.hi();
2977 if let Some(before_item_name) = context
2979 .opt_span_before(mk_sp(vis.span.lo(), ident.span.hi()), item_name.trim())
2981 let missing_span = mk_sp(after_vis, before_item_name);
2982 if let Some(result_with_comment) = combine_strs_with_missing_comments(
2988 /* allow_extend */ true,
2990 result = result_with_comment;
2994 result.push_str(rewrite_ident(context, ident));
2999 #[derive(PartialEq, Eq, Clone, Copy)]
3007 context: &RewriteContext<'_>,
3008 generics: &ast::Generics,
3009 brace_style: BraceStyle,
3010 brace_pos: BracePos,
3014 ) -> Option<String> {
3015 let shape = Shape::legacy(context.budget(used_width + offset.width()), offset);
3016 let mut result = rewrite_generics(context, "", generics, shape)?;
3018 // If the generics are not parameterized then generics.span.hi() == 0,
3019 // so we use span.lo(), which is the position after `struct Foo`.
3020 let span_end_before_where = if !generics.params.is_empty() {
3025 let (same_line_brace, missed_comments) = if !generics.where_clause.predicates.is_empty() {
3026 let budget = context.budget(last_line_used_width(&result, offset.width()));
3027 let mut option = WhereClauseOption::snuggled(&result);
3028 if brace_pos == BracePos::None {
3029 option.suppress_comma = true;
3031 let where_clause_str = rewrite_where_clause(
3033 &generics.where_clause,
3035 Shape::legacy(budget, offset.block_only()),
3039 span_end_before_where,
3042 result.push_str(&where_clause_str);
3044 brace_pos == BracePos::ForceSameLine || brace_style == BraceStyle::PreferSameLine,
3045 // missed comments are taken care of in #rewrite_where_clause
3050 brace_pos == BracePos::ForceSameLine
3051 || (result.contains('\n') && brace_style == BraceStyle::PreferSameLine
3052 || brace_style != BraceStyle::AlwaysNextLine)
3053 || trimmed_last_line_width(&result) == 1,
3054 rewrite_missing_comment(
3056 span_end_before_where,
3057 if brace_pos == BracePos::None {
3060 context.snippet_provider.span_before(span, "{")
3068 // add missing comments
3069 let missed_line_comments = missed_comments
3070 .filter(|missed_comments| !missed_comments.is_empty())
3071 .map_or(false, |missed_comments| {
3072 let is_block = is_last_comment_block(&missed_comments);
3073 let sep = if is_block { " " } else { "\n" };
3074 result.push_str(sep);
3075 result.push_str(&missed_comments);
3078 if brace_pos == BracePos::None {
3079 return Some(result);
3081 let total_used_width = last_line_used_width(&result, used_width);
3082 let remaining_budget = context.budget(total_used_width);
3083 // If the same line brace if forced, it indicates that we are rewriting an item with empty body,
3084 // and hence we take the closer into account as well for one line budget.
3085 // We assume that the closer has the same length as the opener.
3086 let overhead = if brace_pos == BracePos::ForceSameLine {
3093 let forbid_same_line_brace = missed_line_comments || overhead > remaining_budget;
3094 if !forbid_same_line_brace && same_line_brace {
3098 result.push_str(&offset.block_only().to_string(context.config));
3105 impl Rewrite for ast::ForeignItem {
3106 fn rewrite(&self, context: &RewriteContext<'_>, shape: Shape) -> Option<String> {
3107 let attrs_str = self.attrs.rewrite(context, shape)?;
3108 // Drop semicolon or it will be interpreted as comment.
3109 // FIXME: this may be a faulty span from libsyntax.
3110 let span = mk_sp(self.span.lo(), self.span.hi() - BytePos(1));
3112 let item_str = match self.kind {
3113 ast::ForeignItemKind::Fn(ref fn_kind) => {
3120 if let Some(ref body) = body {
3121 let mut visitor = FmtVisitor::from_context(context);
3122 visitor.block_indent = shape.indent;
3123 visitor.last_pos = self.span.lo();
3124 let inner_attrs = inner_attributes(&self.attrs);
3125 let fn_ctxt = visit::FnCtxt::Foreign;
3127 visit::FnKind::Fn(fn_ctxt, self.ident, sig, &self.vis, Some(body)),
3134 Some(visitor.buffer.to_owned())
3140 &FnSig::from_method_sig(sig, generics, &self.vis),
3144 .map(|(s, _, _)| format!("{};", s))
3147 ast::ForeignItemKind::Static(ref ty, mutability, _) => {
3148 // FIXME(#21): we're dropping potential comments in between the
3149 // function kw here.
3150 let vis = format_visibility(context, &self.vis);
3151 let mut_str = format_mutability(mutability);
3152 let prefix = format!(
3156 rewrite_ident(context, self.ident)
3164 shape.sub_width(1)?,
3168 ast::ForeignItemKind::TyAlias(ref ty_alias) => {
3169 let (kind, span) = (&ItemVisitorKind::ForeignItem(self), self.span);
3170 rewrite_type_alias(ty_alias, context, shape.indent, kind, span)
3172 ast::ForeignItemKind::MacCall(ref mac) => {
3173 rewrite_macro(mac, None, context, shape, MacroPosition::Item)
3177 let missing_span = if self.attrs.is_empty() {
3178 mk_sp(self.span.lo(), self.span.lo())
3180 mk_sp(self.attrs[self.attrs.len() - 1].span.hi(), self.span.lo())
3182 combine_strs_with_missing_comments(
3193 /// Rewrite the attributes of an item.
3195 context: &RewriteContext<'_>,
3199 ) -> Option<String> {
3200 let attrs = filter_inline_attrs(&item.attrs, item.span());
3201 let attrs_str = attrs.rewrite(context, shape)?;
3203 let missed_span = if attrs.is_empty() {
3204 mk_sp(item.span.lo(), item.span.lo())
3206 mk_sp(attrs[attrs.len() - 1].span.hi(), item.span.lo())
3209 let allow_extend = if attrs.len() == 1 {
3210 let line_len = attrs_str.len() + 1 + item_str.len();
3211 !attrs.first().unwrap().is_doc_comment()
3212 && context.config.inline_attribute_width() >= line_len
3217 combine_strs_with_missing_comments(
3227 /// Rewrite an inline mod.
3228 /// The given shape is used to format the mod's attributes.
3229 pub(crate) fn rewrite_mod(
3230 context: &RewriteContext<'_>,
3233 ) -> Option<String> {
3234 let mut result = String::with_capacity(32);
3235 result.push_str(&*format_visibility(context, &item.vis));
3236 result.push_str("mod ");
3237 result.push_str(rewrite_ident(context, item.ident));
3239 rewrite_attrs(context, item, &result, attrs_shape)
3242 /// Rewrite `extern crate foo;`.
3243 /// The given shape is used to format the extern crate's attributes.
3244 pub(crate) fn rewrite_extern_crate(
3245 context: &RewriteContext<'_>,
3248 ) -> Option<String> {
3249 assert!(is_extern_crate(item));
3250 let new_str = context.snippet(item.span);
3251 let item_str = if contains_comment(new_str) {
3254 let no_whitespace = &new_str.split_whitespace().collect::<Vec<&str>>().join(" ");
3255 String::from(&*Regex::new(r"\s;").unwrap().replace(no_whitespace, ";"))
3257 rewrite_attrs(context, item, &item_str, attrs_shape)
3260 /// Returns `true` for `mod foo;`, false for `mod foo { .. }`.
3261 pub(crate) fn is_mod_decl(item: &ast::Item) -> bool {
3264 ast::ItemKind::Mod(_, ast::ModKind::Loaded(_, ast::Inline::Yes, _))
3268 pub(crate) fn is_use_item(item: &ast::Item) -> bool {
3269 matches!(item.kind, ast::ItemKind::Use(_))
3272 pub(crate) fn is_extern_crate(item: &ast::Item) -> bool {
3273 matches!(item.kind, ast::ItemKind::ExternCrate(..))