src/types.rs

   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.
   4 //
   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.
  10
  11 use std::ops::Deref;
  12 use std::iter::ExactSizeIterator;
  13
  14 use syntax::ast::{self, Mutability, FunctionRetTy};
  15 use syntax::print::pprust;
  16 use syntax::codemap::{self, Span, BytePos};
  17 use syntax::abi;
  18
  19 use {Indent, Spanned};
  20 use codemap::SpanUtils;
  21 use lists::{format_item_list, itemize_list, format_fn_args};
  22 use rewrite::{Rewrite, RewriteContext};
  23 use utils::{extra_offset, format_mutability, wrap_str};
  24 use expr::{rewrite_unary_prefix, rewrite_pair, rewrite_tuple};
  25 use config::TypeDensity;
  26 use itertools::Itertools;
  27
  28 // Does not wrap on simple segments.
  29 pub fn rewrite_path(context: &RewriteContext,
  30                     expr_context: bool,
  31                     qself: Option<&ast::QSelf>,
  32                     path: &ast::Path,
  33                     width: usize,
  34                     offset: Indent)
  35                     -> Option<String> {
  36     let skip_count = qself.map_or(0, |x| x.position);
  37
  38     let mut result = if path.global && qself.is_none() {
  39         "::".to_owned()
  40     } else {
  41         String::new()
  42     };
  43
  44     let mut span_lo = path.span.lo;
  45
  46     if let Some(ref qself) = qself {
  47         result.push('<');
  48         let fmt_ty = try_opt!(qself.ty.rewrite(context, width, offset));
  49         result.push_str(&fmt_ty);
  50
  51         if skip_count > 0 {
  52             result.push_str(" as ");
  53             if path.global {
  54                 result.push_str("::");
  55             }
  56
  57             let extra_offset = extra_offset(&result, offset);
  58             // 3 = ">::".len()
  59             let budget = try_opt!(width.checked_sub(extra_offset + 3));
  60
  61             result = try_opt!(rewrite_path_segments(false,
  62                                                     result,
  63                                                     path.segments.iter().take(skip_count),
  64                                                     span_lo,
  65                                                     path.span.hi,
  66                                                     context,
  67                                                     budget,
  68                                                     offset + extra_offset));
  69         }
  70
  71         result.push_str(">::");
  72         span_lo = qself.ty.span.hi + BytePos(1);
  73     }
  74
  75     let extra_offset = extra_offset(&result, offset);
  76     let budget = try_opt!(width.checked_sub(extra_offset));
  77     rewrite_path_segments(expr_context,
  78                           result,
  79                           path.segments.iter().skip(skip_count),
  80                           span_lo,
  81                           path.span.hi,
  82                           context,
  83                           budget,
  84                           offset + extra_offset)
  85 }
  86
  87 fn rewrite_path_segments<'a, I>(expr_context: bool,
  88                                 mut buffer: String,
  89                                 iter: I,
  90                                 mut span_lo: BytePos,
  91                                 span_hi: BytePos,
  92                                 context: &RewriteContext,
  93                                 width: usize,
  94                                 offset: Indent)
  95                                 -> Option<String>
  96     where I: Iterator<Item = &'a ast::PathSegment>
  97 {
  98     let mut first = true;
  99
 100     for segment in iter {
 101         if first {
 102             first = false;
 103         } else {
 104             buffer.push_str("::");
 105         }
 106
 107         let extra_offset = extra_offset(&buffer, offset);
 108         let remaining_width = try_opt!(width.checked_sub(extra_offset));
 109         let new_offset = offset + extra_offset;
 110         let segment_string = try_opt!(rewrite_segment(expr_context,
 111                                                       segment,
 112                                                       &mut span_lo,
 113                                                       span_hi,
 114                                                       context,
 115                                                       remaining_width,
 116                                                       new_offset));
 117
 118         buffer.push_str(&segment_string);
 119     }
 120
 121     Some(buffer)
 122 }
 123
 124 #[derive(Debug)]
 125 enum SegmentParam<'a> {
 126     LifeTime(&'a ast::Lifetime),
 127     Type(&'a ast::Ty),
 128     Binding(&'a ast::TypeBinding),
 129 }
 130
 131 impl<'a> SegmentParam<'a> {
 132     fn get_span(&self) -> Span {
 133         match *self {
 134             SegmentParam::LifeTime(ref lt) => lt.span,
 135             SegmentParam::Type(ref ty) => ty.span,
 136             SegmentParam::Binding(ref binding) => binding.span,
 137         }
 138     }
 139 }
 140
 141 impl<'a> Rewrite for SegmentParam<'a> {
 142     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 143         match *self {
 144             SegmentParam::LifeTime(ref lt) => lt.rewrite(context, width, offset),
 145             SegmentParam::Type(ref ty) => ty.rewrite(context, width, offset),
 146             SegmentParam::Binding(ref binding) => {
 147                 let mut result = format!("{} = ", binding.ident);
 148                 let budget = try_opt!(width.checked_sub(result.len()));
 149                 let rewrite = try_opt!(binding.ty.rewrite(context, budget, offset + result.len()));
 150                 result.push_str(&rewrite);
 151                 Some(result)
 152             }
 153         }
 154     }
 155 }
 156
 157 // Formats a path segment. There are some hacks involved to correctly determine
 158 // the segment's associated span since it's not part of the AST.
 159 //
 160 // The span_lo is assumed to be greater than the end of any previous segment's
 161 // parameters and lesser or equal than the start of current segment.
 162 //
 163 // span_hi is assumed equal to the end of the entire path.
 164 //
 165 // When the segment contains a positive number of parameters, we update span_lo
 166 // so that invariants described above will hold for the next segment.
 167 fn rewrite_segment(expr_context: bool,
 168                    segment: &ast::PathSegment,
 169                    span_lo: &mut BytePos,
 170                    span_hi: BytePos,
 171                    context: &RewriteContext,
 172                    width: usize,
 173                    offset: Indent)
 174                    -> Option<String> {
 175     let ident_len = segment.identifier.to_string().len();
 176     let width = try_opt!(width.checked_sub(ident_len));
 177     let offset = offset + ident_len;
 178
 179     let params = match segment.parameters {
 180         ast::PathParameters::AngleBracketed(ref data) if !data.lifetimes.is_empty() ||
 181                                                          !data.types.is_empty() ||
 182                                                          !data.bindings.is_empty() => {
 183             let param_list = data.lifetimes
 184                 .iter()
 185                 .map(SegmentParam::LifeTime)
 186                 .chain(data.types.iter().map(|x| SegmentParam::Type(&*x)))
 187                 .chain(data.bindings.iter().map(|x| SegmentParam::Binding(&*x)))
 188                 .collect::<Vec<_>>();
 189
 190             let next_span_lo = param_list.last().unwrap().get_span().hi + BytePos(1);
 191             let list_lo = context.codemap.span_after(codemap::mk_sp(*span_lo, span_hi), "<");
 192             let separator = if expr_context { "::" } else { "" };
 193
 194             // 1 for <
 195             let extra_offset = 1 + separator.len();
 196             // 1 for >
 197             let list_width = try_opt!(width.checked_sub(extra_offset + 1));
 198
 199             let items = itemize_list(context.codemap,
 200                                      param_list.into_iter(),
 201                                      ">",
 202                                      |param| param.get_span().lo,
 203                                      |param| param.get_span().hi,
 204                                      |seg| seg.rewrite(context, list_width, offset + extra_offset),
 205                                      list_lo,
 206                                      span_hi);
 207             let list_str = try_opt!(format_item_list(items,
 208                                                      list_width,
 209                                                      offset + extra_offset,
 210                                                      context.config));
 211
 212             // Update position of last bracket.
 213             *span_lo = next_span_lo;
 214
 215             format!("{}<{}>", separator, list_str)
 216         }
 217         ast::PathParameters::Parenthesized(ref data) => {
 218             let output = match data.output {
 219                 Some(ref ty) => FunctionRetTy::Ty(ty.clone()),
 220                 None => FunctionRetTy::Default(codemap::DUMMY_SP),
 221             };
 222             try_opt!(format_function_type(data.inputs.iter().map(|x| &**x),
 223                                           &output,
 224                                           false,
 225                                           data.span,
 226                                           context,
 227                                           width,
 228                                           offset))
 229         }
 230         _ => String::new(),
 231     };
 232
 233     Some(format!("{}{}", segment.identifier, params))
 234 }
 235
 236 fn format_function_type<'a, I>(inputs: I,
 237                                output: &FunctionRetTy,
 238                                variadic: bool,
 239                                span: Span,
 240                                context: &RewriteContext,
 241                                width: usize,
 242                                offset: Indent)
 243                                -> Option<String>
 244     where I: ExactSizeIterator,
 245           <I as Iterator>::Item: Deref,
 246           <I::Item as Deref>::Target: Rewrite + Spanned + 'a
 247 {
 248     // Code for handling variadics is somewhat duplicated for items, but they
 249     // are different enough to need some serious refactoring to share code.
 250     enum ArgumentKind<T>
 251         where T: Deref,
 252               <T as Deref>::Target: Rewrite + Spanned
 253     {
 254         Regular(Box<T>),
 255         Variadic(BytePos),
 256     }
 257
 258     let variadic_arg = if variadic {
 259         let variadic_start = context.codemap.span_before(span, "...");
 260         Some(ArgumentKind::Variadic(variadic_start))
 261     } else {
 262         None
 263     };
 264
 265     // 2 for ()
 266     let budget = try_opt!(width.checked_sub(2));
 267     // 1 for (
 268     let offset = offset + 1;
 269     let list_lo = context.codemap.span_after(span, "(");
 270     let items = itemize_list(context.codemap,
 271                              // FIXME Would be nice to avoid this allocation,
 272                              // but I couldn't get the types to work out.
 273                              inputs.map(|i| ArgumentKind::Regular(Box::new(i)))
 274                                  .chain(variadic_arg),
 275                              ")",
 276                              |arg| {
 277                                  match *arg {
 278                                      ArgumentKind::Regular(ref ty) => ty.span().lo,
 279                                      ArgumentKind::Variadic(start) => start,
 280                                  }
 281                              },
 282                              |arg| {
 283                                  match *arg {
 284                                      ArgumentKind::Regular(ref ty) => ty.span().hi,
 285                                      ArgumentKind::Variadic(start) => start + BytePos(3),
 286                                  }
 287                              },
 288                              |arg| {
 289         match *arg {
 290             ArgumentKind::Regular(ref ty) => ty.rewrite(context, budget, offset),
 291             ArgumentKind::Variadic(_) => Some("...".to_owned()),
 292         }
 293     },
 294                              list_lo,
 295                              span.hi);
 296
 297     let list_str = try_opt!(format_fn_args(items, budget, offset, context.config));
 298
 299     let output = match *output {
 300         FunctionRetTy::Ty(ref ty) => {
 301             let budget = try_opt!(width.checked_sub(4));
 302             let type_str = try_opt!(ty.rewrite(context, budget, offset + 4));
 303             format!(" -> {}", type_str)
 304         }
 305         FunctionRetTy::None(..) => " -> !".to_owned(),
 306         FunctionRetTy::Default(..) => String::new(),
 307     };
 308
 309     let infix = if output.len() > 0 && output.len() + list_str.len() > width {
 310         format!("\n{}", (offset - 1).to_string(context.config))
 311     } else {
 312         String::new()
 313     };
 314
 315     Some(format!("({}){}{}", list_str, infix, output))
 316 }
 317
 318 impl Rewrite for ast::WherePredicate {
 319     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 320         // TODO: dead spans?
 321         let result = match *self {
 322             ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate { ref bound_lifetimes,
 323                                                                            ref bounded_ty,
 324                                                                            ref bounds,
 325                                                                            .. }) => {
 326                 let type_str = try_opt!(bounded_ty.rewrite(context, width, offset));
 327
 328                 if !bound_lifetimes.is_empty() {
 329                     let lifetime_str: String = try_opt!(bound_lifetimes.iter()
 330                                                                .map(|lt| {
 331                                                                    lt.rewrite(context,
 332                                                                               width,
 333                                                                               offset)
 334                                                                })
 335                                                                .intersperse(Some(", ".to_string()))
 336                                                                .collect());
 337
 338                     // 8 = "for<> : ".len()
 339                     let used_width = lifetime_str.len() + type_str.len() + 8;
 340                     let budget = try_opt!(width.checked_sub(used_width));
 341                     let bounds_str: String = try_opt!(bounds.iter()
 342                                                     .map(|ty_bound| {
 343                                                         ty_bound.rewrite(context,
 344                                                                          budget,
 345                                                                          offset + used_width)
 346                                                     })
 347                                                     .intersperse(Some(" + ".to_string()))
 348                                                     .collect());
 349
 350                     format!("for<{}> {}: {}", lifetime_str, type_str, bounds_str)
 351                 } else {
 352                     // 2 = ": ".len()
 353                     let used_width = type_str.len() + 2;
 354                     let budget = try_opt!(width.checked_sub(used_width));
 355                     let bounds_str: String = try_opt!(bounds.iter()
 356                                                     .map(|ty_bound| {
 357                                                         ty_bound.rewrite(context,
 358                                                                          budget,
 359                                                                          offset + used_width)
 360                                                     })
 361                                                     .intersperse(Some(" + ".to_string()))
 362                                                     .collect());
 363
 364                     format!("{}: {}", type_str, bounds_str)
 365                 }
 366             }
 367             ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate { ref lifetime,
 368                                                                              ref bounds,
 369                                                                              .. }) => {
 370                 try_opt!(rewrite_bounded_lifetime(lifetime, bounds.iter(), context, width, offset))
 371             }
 372             ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { ref path, ref ty, .. }) => {
 373                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 374                 // 3 = " = ".len()
 375                 let used_width = 3 + ty_str.len();
 376                 let budget = try_opt!(width.checked_sub(used_width));
 377                 let path_str =
 378                     try_opt!(rewrite_path(context, false, None, path, budget, offset + used_width));
 379                 format!("{} = {}", path_str, ty_str)
 380             }
 381         };
 382
 383         wrap_str(result, context.config.max_width, width, offset)
 384     }
 385 }
 386
 387 impl Rewrite for ast::LifetimeDef {
 388     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 389         rewrite_bounded_lifetime(&self.lifetime, self.bounds.iter(), context, width, offset)
 390     }
 391 }
 392
 393 fn rewrite_bounded_lifetime<'b, I>(lt: &ast::Lifetime,
 394                                    bounds: I,
 395                                    context: &RewriteContext,
 396                                    width: usize,
 397                                    offset: Indent)
 398                                    -> Option<String>
 399     where I: ExactSizeIterator<Item = &'b ast::Lifetime>
 400 {
 401     let result = try_opt!(lt.rewrite(context, width, offset));
 402
 403     if bounds.len() == 0 {
 404         Some(result)
 405     } else {
 406         let appendix: Vec<_> = try_opt!(bounds.into_iter()
 407             .map(|b| b.rewrite(context, width, offset))
 408             .collect());
 409         let result = format!("{}: {}", result, appendix.join(" + "));
 410         wrap_str(result, context.config.max_width, width, offset)
 411     }
 412 }
 413
 414 impl Rewrite for ast::TyParamBound {
 415     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 416         match *self {
 417             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::None) => {
 418                 tref.rewrite(context, width, offset)
 419             }
 420             ast::TyParamBound::TraitTyParamBound(ref tref, ast::TraitBoundModifier::Maybe) => {
 421                 let budget = try_opt!(width.checked_sub(1));
 422                 Some(format!("?{}", try_opt!(tref.rewrite(context, budget, offset + 1))))
 423             }
 424             ast::TyParamBound::RegionTyParamBound(ref l) => l.rewrite(context, width, offset),
 425         }
 426     }
 427 }
 428
 429 impl Rewrite for ast::Lifetime {
 430     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 431         wrap_str(pprust::lifetime_to_string(self),
 432                  context.config.max_width,
 433                  width,
 434                  offset)
 435     }
 436 }
 437
 438 impl Rewrite for ast::TyParamBounds {
 439     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 440         let strs: Vec<_> = try_opt!(self.iter()
 441             .map(|b| b.rewrite(context, width, offset))
 442             .collect());
 443         wrap_str(strs.join(" + "), context.config.max_width, width, offset)
 444     }
 445 }
 446
 447 impl Rewrite for ast::TyParam {
 448     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 449         let mut result = String::with_capacity(128);
 450         result.push_str(&self.ident.to_string());
 451         if !self.bounds.is_empty() {
 452             result.push_str(": ");
 453
 454             let bounds: String = try_opt!(self.bounds
 455                 .iter()
 456                 .map(|ty_bound| ty_bound.rewrite(context, width, offset))
 457                 .intersperse(Some(" + ".to_string()))
 458                 .collect());
 459
 460             result.push_str(&bounds);
 461         }
 462         if let Some(ref def) = self.default {
 463
 464             let eq_str = match context.config.type_punctuation_density {
 465                 TypeDensity::Compressed => "=",
 466                 TypeDensity::Wide => " = ",
 467             };
 468             result.push_str(eq_str);
 469             let budget = try_opt!(width.checked_sub(result.len()));
 470             let rewrite = try_opt!(def.rewrite(context, budget, offset + result.len()));
 471             result.push_str(&rewrite);
 472         }
 473
 474         wrap_str(result, context.config.max_width, width, offset)
 475     }
 476 }
 477
 478 impl Rewrite for ast::PolyTraitRef {
 479     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 480         if !self.bound_lifetimes.is_empty() {
 481             let lifetime_str: String = try_opt!(self.bound_lifetimes
 482                 .iter()
 483                 .map(|lt| lt.rewrite(context, width, offset))
 484                 .intersperse(Some(", ".to_string()))
 485                 .collect());
 486
 487             // 6 is "for<> ".len()
 488             let extra_offset = lifetime_str.len() + 6;
 489             let max_path_width = try_opt!(width.checked_sub(extra_offset));
 490             let path_str = try_opt!(self.trait_ref
 491                 .rewrite(context, max_path_width, offset + extra_offset));
 492
 493             Some(format!("for<{}> {}", lifetime_str, path_str))
 494         } else {
 495             self.trait_ref.rewrite(context, width, offset)
 496         }
 497     }
 498 }
 499
 500 impl Rewrite for ast::TraitRef {
 501     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 502         rewrite_path(context, false, None, &self.path, width, offset)
 503     }
 504 }
 505
 506 impl Rewrite for ast::Ty {
 507     fn rewrite(&self, context: &RewriteContext, width: usize, offset: Indent) -> Option<String> {
 508         match self.node {
 509             ast::TyKind::ObjectSum(ref ty, ref bounds) => {
 510                 let ty_str = try_opt!(ty.rewrite(context, width, offset));
 511                 let overhead = ty_str.len() + 3;
 512                 let plus_str = match context.config.type_punctuation_density {
 513                     TypeDensity::Compressed => "+",
 514                     TypeDensity::Wide => " + ",
 515                 };
 516                 Some(format!("{}{}{}",
 517                              ty_str,
 518                              plus_str,
 519                              try_opt!(bounds.rewrite(context,
 520                                                      try_opt!(width.checked_sub(overhead)),
 521                                                      offset + overhead))))
 522             }
 523             ast::TyKind::Ptr(ref mt) => {
 524                 let prefix = match mt.mutbl {
 525                     Mutability::Mutable => "*mut ",
 526                     Mutability::Immutable => "*const ",
 527                 };
 528
 529                 rewrite_unary_prefix(context, prefix, &*mt.ty, width, offset)
 530             }
 531             ast::TyKind::Rptr(ref lifetime, ref mt) => {
 532                 let mut_str = format_mutability(mt.mutbl);
 533                 let mut_len = mut_str.len();
 534                 Some(match *lifetime {
 535                     Some(ref lifetime) => {
 536                         let lt_budget = try_opt!(width.checked_sub(2 + mut_len));
 537                         let lt_str =
 538                             try_opt!(lifetime.rewrite(context, lt_budget, offset + 2 + mut_len));
 539                         let lt_len = lt_str.len();
 540                         let budget = try_opt!(width.checked_sub(2 + mut_len + lt_len));
 541                         format!("&{} {}{}",
 542                                 lt_str,
 543                                 mut_str,
 544                                 try_opt!(mt.ty
 545                                     .rewrite(context, budget, offset + 2 + mut_len + lt_len)))
 546                     }
 547                     None => {
 548                         let budget = try_opt!(width.checked_sub(1 + mut_len));
 549                         format!("&{}{}",
 550                                 mut_str,
 551                                 try_opt!(mt.ty.rewrite(context, budget, offset + 1 + mut_len)))
 552                     }
 553                 })
 554             }
 555             // FIXME: we drop any comments here, even though it's a silly place to put
 556             // comments.
 557             ast::TyKind::Paren(ref ty) => {
 558                 let budget = try_opt!(width.checked_sub(2));
 559                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("({})", ty_str))
 560             }
 561             ast::TyKind::Vec(ref ty) => {
 562                 let budget = try_opt!(width.checked_sub(2));
 563                 ty.rewrite(context, budget, offset + 1).map(|ty_str| format!("[{}]", ty_str))
 564             }
 565             ast::TyKind::Tup(ref items) => {
 566                 rewrite_tuple(context,
 567                               items.iter().map(|x| &**x),
 568                               self.span,
 569                               width,
 570                               offset)
 571             }
 572             ast::TyKind::PolyTraitRef(ref trait_ref) => trait_ref.rewrite(context, width, offset),
 573             ast::TyKind::Path(ref q_self, ref path) => {
 574                 rewrite_path(context, false, q_self.as_ref(), path, width, offset)
 575             }
 576             ast::TyKind::FixedLengthVec(ref ty, ref repeats) => {
 577                 rewrite_pair(&**ty, &**repeats, "[", "; ", "]", context, width, offset)
 578             }
 579             ast::TyKind::Infer => {
 580                 if width >= 1 {
 581                     Some("_".to_owned())
 582                 } else {
 583                     None
 584                 }
 585             }
 586             ast::TyKind::BareFn(ref bare_fn) => {
 587                 rewrite_bare_fn(bare_fn, self.span, context, width, offset)
 588             }
 589             ast::TyKind::Mac(..) |
 590             ast::TyKind::Typeof(..) => unreachable!(),
 591             ast::TyKind::ImplicitSelf => Some(String::from("")),
 592         }
 593     }
 594 }
 595
 596 fn rewrite_bare_fn(bare_fn: &ast::BareFnTy,
 597                    span: Span,
 598                    context: &RewriteContext,
 599                    width: usize,
 600                    offset: Indent)
 601                    -> Option<String> {
 602     let mut result = String::with_capacity(128);
 603
 604     if !bare_fn.lifetimes.is_empty() {
 605         result.push_str("for<");
 606         // 6 = "for<> ".len(), 4 = "for<".
 607         // This doesn't work out so nicely for mutliline situation with lots of
 608         // rightward drift. If that is a problem, we could use the list stuff.
 609         result.push_str(&try_opt!(bare_fn.lifetimes
 610             .iter()
 611             .map(|l| l.rewrite(context, try_opt!(width.checked_sub(6)), offset + 4))
 612             .intersperse(Some(", ".to_string()))
 613             .collect::<Option<String>>()));
 614         result.push_str("> ");
 615     }
 616
 617     result.push_str(&::utils::format_unsafety(bare_fn.unsafety));
 618
 619     if bare_fn.abi != abi::Abi::Rust {
 620         result.push_str(&::utils::format_abi(bare_fn.abi, context.config.force_explicit_abi));
 621     }
 622
 623     result.push_str("fn");
 624
 625     let budget = try_opt!(width.checked_sub(result.len()));
 626     let indent = offset + result.len();
 627
 628     let rewrite = try_opt!(format_function_type(bare_fn.decl.inputs.iter(),
 629                                                 &bare_fn.decl.output,
 630                                                 bare_fn.decl.variadic,
 631                                                 span,
 632                                                 context,
 633                                                 budget,
 634                                                 indent));
 635
 636     result.push_str(&rewrite);
 637
 638     Some(result)
 639 }