src/visitor.rs

   1 use std::cell::{Cell, RefCell};
   2 use std::rc::Rc;
   3
   4 use rustc_ast::{ast, token::DelimToken, visit, AstLike};
   5 use rustc_data_structures::sync::Lrc;
   6 use rustc_span::{symbol, BytePos, Pos, Span};
   7
   8 use crate::attr::*;
   9 use crate::comment::{contains_comment, rewrite_comment, CodeCharKind, CommentCodeSlices};
  10 use crate::config::Version;
  11 use crate::config::{BraceStyle, Config};
  12 use crate::coverage::transform_missing_snippet;
  13 use crate::items::{
  14     format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item, rewrite_extern_crate,
  15     rewrite_type_alias, FnBraceStyle, FnSig, ItemVisitorKind, StaticParts, StructParts,
  16 };
  17 use crate::macros::{macro_style, rewrite_macro, rewrite_macro_def, MacroPosition};
  18 use crate::modules::Module;
  19 use crate::parse::session::ParseSess;
  20 use crate::rewrite::{Memoize, Rewrite, RewriteContext};
  21 use crate::shape::{Indent, Shape};
  22 use crate::skip::{is_skip_attr, SkipContext};
  23 use crate::source_map::{LineRangeUtils, SpanUtils};
  24 use crate::spanned::Spanned;
  25 use crate::stmt::Stmt;
  26 use crate::utils::{
  27     self, contains_skip, count_newlines, depr_skip_annotation, format_unsafety, inner_attributes,
  28     last_line_width, mk_sp, ptr_vec_to_ref_vec, rewrite_ident, starts_with_newline, stmt_expr,
  29 };
  30 use crate::{ErrorKind, FormatReport, FormattingError};
  31
  32 /// Creates a string slice corresponding to the specified span.
  33 pub(crate) struct SnippetProvider {
  34     /// A pointer to the content of the file we are formatting.
  35     big_snippet: Lrc<String>,
  36     /// A position of the start of `big_snippet`, used as an offset.
  37     start_pos: usize,
  38     /// An end position of the file that this snippet lives.
  39     end_pos: usize,
  40 }
  41
  42 impl SnippetProvider {
  43     pub(crate) fn span_to_snippet(&self, span: Span) -> Option<&str> {
  44         let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
  45         let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
  46         Some(&self.big_snippet[start_index..end_index])
  47     }
  48
  49     pub(crate) fn new(start_pos: BytePos, end_pos: BytePos, big_snippet: Lrc<String>) -> Self {
  50         let start_pos = start_pos.to_usize();
  51         let end_pos = end_pos.to_usize();
  52         SnippetProvider {
  53             big_snippet,
  54             start_pos,
  55             end_pos,
  56         }
  57     }
  58
  59     pub(crate) fn entire_snippet(&self) -> &str {
  60         self.big_snippet.as_str()
  61     }
  62
  63     pub(crate) fn start_pos(&self) -> BytePos {
  64         BytePos::from_usize(self.start_pos)
  65     }
  66
  67     pub(crate) fn end_pos(&self) -> BytePos {
  68         BytePos::from_usize(self.end_pos)
  69     }
  70 }
  71
  72 pub(crate) struct FmtVisitor<'a> {
  73     parent_context: Option<&'a RewriteContext<'a>>,
  74     pub(crate) memoize: Memoize,
  75     pub(crate) parse_sess: &'a ParseSess,
  76     pub(crate) buffer: String,
  77     pub(crate) last_pos: BytePos,
  78     // FIXME: use an RAII util or closure for indenting
  79     pub(crate) block_indent: Indent,
  80     pub(crate) config: &'a Config,
  81     pub(crate) is_if_else_block: bool,
  82     pub(crate) snippet_provider: &'a SnippetProvider,
  83     pub(crate) line_number: usize,
  84     /// List of 1-based line ranges which were annotated with skip
  85     /// Both bounds are inclusifs.
  86     pub(crate) skipped_range: Rc<RefCell<Vec<(usize, usize)>>>,
  87     pub(crate) macro_rewrite_failure: bool,
  88     pub(crate) report: FormatReport,
  89     pub(crate) skip_context: SkipContext,
  90     pub(crate) is_macro_def: bool,
  91 }
  92
  93 impl<'a> Drop for FmtVisitor<'a> {
  94     fn drop(&mut self) {
  95         if let Some(ctx) = self.parent_context {
  96             if self.macro_rewrite_failure {
  97                 ctx.macro_rewrite_failure.replace(true);
  98             }
  99         }
 100     }
 101 }
 102
 103 impl<'b, 'a: 'b> FmtVisitor<'a> {
 104     fn set_parent_context(&mut self, context: &'a RewriteContext<'_>) {
 105         self.parent_context = Some(context);
 106     }
 107
 108     pub(crate) fn shape(&self) -> Shape {
 109         Shape::indented(self.block_indent, self.config)
 110     }
 111
 112     fn next_span(&self, hi: BytePos) -> Span {
 113         mk_sp(self.last_pos, hi)
 114     }
 115
 116     fn visit_stmt(&mut self, stmt: &Stmt<'_>, include_empty_semi: bool) {
 117         debug!(
 118             "visit_stmt: {}",
 119             self.parse_sess.span_to_debug_info(stmt.span())
 120         );
 121
 122         if stmt.is_empty() {
 123             // If the statement is empty, just skip over it. Before that, make sure any comment
 124             // snippet preceding the semicolon is picked up.
 125             let snippet = self.snippet(mk_sp(self.last_pos, stmt.span().lo()));
 126             let original_starts_with_newline = snippet
 127                 .find(|c| c != ' ')
 128                 .map_or(false, |i| starts_with_newline(&snippet[i..]));
 129             let snippet = snippet.trim();
 130             if !snippet.is_empty() {
 131                 // FIXME(calebcartwright 2021-01-03) - This exists strictly to maintain legacy
 132                 // formatting where rustfmt would preserve redundant semicolons on Items in a
 133                 // statement position.
 134                 // See comment within `walk_stmts` for more info
 135                 if include_empty_semi {
 136                     self.format_missing(stmt.span().hi());
 137                 } else {
 138                     if original_starts_with_newline {
 139                         self.push_str("\n");
 140                     }
 141
 142                     self.push_str(&self.block_indent.to_string(self.config));
 143                     self.push_str(snippet);
 144                 }
 145             } else if include_empty_semi {
 146                 self.push_str(";");
 147             }
 148             self.last_pos = stmt.span().hi();
 149             return;
 150         }
 151
 152         match stmt.as_ast_node().kind {
 153             ast::StmtKind::Item(ref item) => {
 154                 self.visit_item(item);
 155                 self.last_pos = stmt.span().hi();
 156             }
 157             ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
 158                 let attrs = get_attrs_from_stmt(stmt.as_ast_node());
 159                 if contains_skip(attrs) {
 160                     self.push_skipped_with_span(
 161                         attrs,
 162                         stmt.span(),
 163                         get_span_without_attrs(stmt.as_ast_node()),
 164                     );
 165                 } else {
 166                     let shape = self.shape();
 167                     let rewrite = self.with_context(|ctx| stmt.rewrite(ctx, shape));
 168                     self.push_rewrite(stmt.span(), rewrite)
 169                 }
 170             }
 171             ast::StmtKind::MacCall(ref mac_stmt) => {
 172                 if self.visit_attrs(&mac_stmt.attrs, ast::AttrStyle::Outer) {
 173                     self.push_skipped_with_span(
 174                         &mac_stmt.attrs,
 175                         stmt.span(),
 176                         get_span_without_attrs(stmt.as_ast_node()),
 177                     );
 178                 } else {
 179                     self.visit_mac(&mac_stmt.mac, None, MacroPosition::Statement);
 180                 }
 181                 self.format_missing(stmt.span().hi());
 182             }
 183             ast::StmtKind::Empty => (),
 184         }
 185     }
 186
 187     /// Remove spaces between the opening brace and the first statement or the inner attribute
 188     /// of the block.
 189     fn trim_spaces_after_opening_brace(
 190         &mut self,
 191         b: &ast::Block,
 192         inner_attrs: Option<&[ast::Attribute]>,
 193     ) {
 194         if let Some(first_stmt) = b.stmts.first() {
 195             let hi = inner_attrs
 196                 .and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
 197                 .unwrap_or_else(|| first_stmt.span().lo());
 198             let missing_span = self.next_span(hi);
 199             let snippet = self.snippet(missing_span);
 200             let len = CommentCodeSlices::new(snippet)
 201                 .next()
 202                 .and_then(|(kind, _, s)| {
 203                     if kind == CodeCharKind::Normal {
 204                         s.rfind('\n')
 205                     } else {
 206                         None
 207                     }
 208                 });
 209             if let Some(len) = len {
 210                 self.last_pos = self.last_pos + BytePos::from_usize(len);
 211             }
 212         }
 213     }
 214
 215     pub(crate) fn visit_block(
 216         &mut self,
 217         b: &ast::Block,
 218         inner_attrs: Option<&[ast::Attribute]>,
 219         has_braces: bool,
 220     ) {
 221         debug!(
 222             "visit_block: {}",
 223             self.parse_sess.span_to_debug_info(b.span),
 224         );
 225
 226         // Check if this block has braces.
 227         let brace_compensation = BytePos(if has_braces { 1 } else { 0 });
 228
 229         self.last_pos = self.last_pos + brace_compensation;
 230         self.block_indent = self.block_indent.block_indent(self.config);
 231         self.push_str("{");
 232         self.trim_spaces_after_opening_brace(b, inner_attrs);
 233
 234         // Format inner attributes if available.
 235         if let Some(attrs) = inner_attrs {
 236             self.visit_attrs(attrs, ast::AttrStyle::Inner);
 237         }
 238
 239         self.walk_block_stmts(b);
 240
 241         if !b.stmts.is_empty() {
 242             if let Some(expr) = stmt_expr(&b.stmts[b.stmts.len() - 1]) {
 243                 if utils::semicolon_for_expr(&self.get_context(), expr) {
 244                     self.push_str(";");
 245                 }
 246             }
 247         }
 248
 249         let rest_span = self.next_span(b.span.hi());
 250         if out_of_file_lines_range!(self, rest_span) {
 251             self.push_str(self.snippet(rest_span));
 252             self.block_indent = self.block_indent.block_unindent(self.config);
 253         } else {
 254             // Ignore the closing brace.
 255             let missing_span = self.next_span(b.span.hi() - brace_compensation);
 256             self.close_block(missing_span, self.unindent_comment_on_closing_brace(b));
 257         }
 258         self.last_pos = source!(self, b.span).hi();
 259     }
 260
 261     fn close_block(&mut self, span: Span, unindent_comment: bool) {
 262         let config = self.config;
 263
 264         let mut last_hi = span.lo();
 265         let mut unindented = false;
 266         let mut prev_ends_with_newline = false;
 267         let mut extra_newline = false;
 268
 269         let skip_normal = |s: &str| {
 270             let trimmed = s.trim();
 271             trimmed.is_empty() || trimmed.chars().all(|c| c == ';')
 272         };
 273
 274         let comment_snippet = self.snippet(span);
 275
 276         let align_to_right = if unindent_comment && contains_comment(comment_snippet) {
 277             let first_lines = comment_snippet.splitn(2, '/').next().unwrap_or("");
 278             last_line_width(first_lines) > last_line_width(comment_snippet)
 279         } else {
 280             false
 281         };
 282
 283         for (kind, offset, sub_slice) in CommentCodeSlices::new(comment_snippet) {
 284             let sub_slice = transform_missing_snippet(config, sub_slice);
 285
 286             debug!("close_block: {:?} {:?} {:?}", kind, offset, sub_slice);
 287
 288             match kind {
 289                 CodeCharKind::Comment => {
 290                     if !unindented && unindent_comment && !align_to_right {
 291                         unindented = true;
 292                         self.block_indent = self.block_indent.block_unindent(config);
 293                     }
 294                     let span_in_between = mk_sp(last_hi, span.lo() + BytePos::from_usize(offset));
 295                     let snippet_in_between = self.snippet(span_in_between);
 296                     let mut comment_on_same_line = !snippet_in_between.contains('\n');
 297
 298                     let mut comment_shape =
 299                         Shape::indented(self.block_indent, config).comment(config);
 300                     if self.config.version() == Version::Two && comment_on_same_line {
 301                         self.push_str(" ");
 302                         // put the first line of the comment on the same line as the
 303                         // block's last line
 304                         match sub_slice.find('\n') {
 305                             None => {
 306                                 self.push_str(&sub_slice);
 307                             }
 308                             Some(offset) if offset + 1 == sub_slice.len() => {
 309                                 self.push_str(&sub_slice[..offset]);
 310                             }
 311                             Some(offset) => {
 312                                 let first_line = &sub_slice[..offset];
 313                                 self.push_str(first_line);
 314                                 self.push_str(&self.block_indent.to_string_with_newline(config));
 315
 316                                 // put the other lines below it, shaping it as needed
 317                                 let other_lines = &sub_slice[offset + 1..];
 318                                 let comment_str =
 319                                     rewrite_comment(other_lines, false, comment_shape, config);
 320                                 match comment_str {
 321                                     Some(ref s) => self.push_str(s),
 322                                     None => self.push_str(other_lines),
 323                                 }
 324                             }
 325                         }
 326                     } else {
 327                         if comment_on_same_line {
 328                             // 1 = a space before `//`
 329                             let offset_len = 1 + last_line_width(&self.buffer)
 330                                 .saturating_sub(self.block_indent.width());
 331                             match comment_shape
 332                                 .visual_indent(offset_len)
 333                                 .sub_width(offset_len)
 334                             {
 335                                 Some(shp) => comment_shape = shp,
 336                                 None => comment_on_same_line = false,
 337                             }
 338                         };
 339
 340                         if comment_on_same_line {
 341                             self.push_str(" ");
 342                         } else {
 343                             if count_newlines(snippet_in_between) >= 2 || extra_newline {
 344                                 self.push_str("\n");
 345                             }
 346                             self.push_str(&self.block_indent.to_string_with_newline(config));
 347                         }
 348
 349                         let comment_str = rewrite_comment(&sub_slice, false, comment_shape, config);
 350                         match comment_str {
 351                             Some(ref s) => self.push_str(s),
 352                             None => self.push_str(&sub_slice),
 353                         }
 354                     }
 355                 }
 356                 CodeCharKind::Normal if skip_normal(&sub_slice) => {
 357                     extra_newline = prev_ends_with_newline && sub_slice.contains('\n');
 358                     continue;
 359                 }
 360                 CodeCharKind::Normal => {
 361                     self.push_str(&self.block_indent.to_string_with_newline(config));
 362                     self.push_str(sub_slice.trim());
 363                 }
 364             }
 365             prev_ends_with_newline = sub_slice.ends_with('\n');
 366             extra_newline = false;
 367             last_hi = span.lo() + BytePos::from_usize(offset + sub_slice.len());
 368         }
 369         if unindented {
 370             self.block_indent = self.block_indent.block_indent(self.config);
 371         }
 372         self.block_indent = self.block_indent.block_unindent(self.config);
 373         self.push_str(&self.block_indent.to_string_with_newline(config));
 374         self.push_str("}");
 375     }
 376
 377     fn unindent_comment_on_closing_brace(&self, b: &ast::Block) -> bool {
 378         self.is_if_else_block && !b.stmts.is_empty()
 379     }
 380
 381     // Note that this only gets called for function definitions. Required methods
 382     // on traits do not get handled here.
 383     pub(crate) fn visit_fn(
 384         &mut self,
 385         fk: visit::FnKind<'_>,
 386         generics: &ast::Generics,
 387         fd: &ast::FnDecl,
 388         s: Span,
 389         defaultness: ast::Defaultness,
 390         inner_attrs: Option<&[ast::Attribute]>,
 391     ) {
 392         let indent = self.block_indent;
 393         let block;
 394         let rewrite = match fk {
 395             visit::FnKind::Fn(_, ident, _, _, Some(ref b)) => {
 396                 block = b;
 397                 self.rewrite_fn_before_block(
 398                     indent,
 399                     ident,
 400                     &FnSig::from_fn_kind(&fk, generics, fd, defaultness),
 401                     mk_sp(s.lo(), b.span.lo()),
 402                 )
 403             }
 404             _ => unreachable!(),
 405         };
 406
 407         if let Some((fn_str, fn_brace_style)) = rewrite {
 408             self.format_missing_with_indent(source!(self, s).lo());
 409
 410             if let Some(rw) = self.single_line_fn(&fn_str, block, inner_attrs) {
 411                 self.push_str(&rw);
 412                 self.last_pos = s.hi();
 413                 return;
 414             }
 415
 416             self.push_str(&fn_str);
 417             match fn_brace_style {
 418                 FnBraceStyle::SameLine => self.push_str(" "),
 419                 FnBraceStyle::NextLine => {
 420                     self.push_str(&self.block_indent.to_string_with_newline(self.config))
 421                 }
 422                 _ => unreachable!(),
 423             }
 424             self.last_pos = source!(self, block.span).lo();
 425         } else {
 426             self.format_missing(source!(self, block.span).lo());
 427         }
 428
 429         self.visit_block(block, inner_attrs, true)
 430     }
 431
 432     pub(crate) fn visit_item(&mut self, item: &ast::Item) {
 433         skip_out_of_file_lines_range_visitor!(self, item.span);
 434
 435         // This is where we bail out if there is a skip attribute. This is only
 436         // complex in the module case. It is complex because the module could be
 437         // in a separate file and there might be attributes in both files, but
 438         // the AST lumps them all together.
 439         let filtered_attrs;
 440         let mut attrs = &item.attrs;
 441         let skip_context_saved = self.skip_context.clone();
 442         self.skip_context.update_with_attrs(attrs);
 443
 444         let should_visit_node_again = match item.kind {
 445             // For use/extern crate items, skip rewriting attributes but check for a skip attribute.
 446             ast::ItemKind::Use(..) | ast::ItemKind::ExternCrate(_) => {
 447                 if contains_skip(attrs) {
 448                     self.push_skipped_with_span(attrs.as_slice(), item.span(), item.span());
 449                     false
 450                 } else {
 451                     true
 452                 }
 453             }
 454             // Module is inline, in this case we treat it like any other item.
 455             _ if !is_mod_decl(item) => {
 456                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 457                     self.push_skipped_with_span(item.attrs.as_slice(), item.span(), item.span());
 458                     false
 459                 } else {
 460                     true
 461                 }
 462             }
 463             // Module is not inline, but should be skipped.
 464             ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => false,
 465             // Module is not inline and should not be skipped. We want
 466             // to process only the attributes in the current file.
 467             ast::ItemKind::Mod(..) => {
 468                 filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
 469                 // Assert because if we should skip it should be caught by
 470                 // the above case.
 471                 assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
 472                 attrs = &filtered_attrs;
 473                 true
 474             }
 475             _ => {
 476                 if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
 477                     self.push_skipped_with_span(item.attrs.as_slice(), item.span(), item.span());
 478                     false
 479                 } else {
 480                     true
 481                 }
 482             }
 483         };
 484
 485         // TODO(calebcartwright): consider enabling box_patterns feature gate
 486         if should_visit_node_again {
 487             match item.kind {
 488                 ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
 489                 ast::ItemKind::Impl(ref iimpl) => {
 490                     let block_indent = self.block_indent;
 491                     let rw = self.with_context(|ctx| format_impl(ctx, item, iimpl, block_indent));
 492                     self.push_rewrite(item.span, rw);
 493                 }
 494                 ast::ItemKind::Trait(..) => {
 495                     let block_indent = self.block_indent;
 496                     let rw = self.with_context(|ctx| format_trait(ctx, item, block_indent));
 497                     self.push_rewrite(item.span, rw);
 498                 }
 499                 ast::ItemKind::TraitAlias(ref generics, ref generic_bounds) => {
 500                     let shape = Shape::indented(self.block_indent, self.config);
 501                     let rw = format_trait_alias(
 502                         &self.get_context(),
 503                         item.ident,
 504                         &item.vis,
 505                         generics,
 506                         generic_bounds,
 507                         shape,
 508                     );
 509                     self.push_rewrite(item.span, rw);
 510                 }
 511                 ast::ItemKind::ExternCrate(_) => {
 512                     let rw = rewrite_extern_crate(&self.get_context(), item, self.shape());
 513                     let span = if attrs.is_empty() {
 514                         item.span
 515                     } else {
 516                         mk_sp(attrs[0].span.lo(), item.span.hi())
 517                     };
 518                     self.push_rewrite(span, rw);
 519                 }
 520                 ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
 521                     self.visit_struct(&StructParts::from_item(item));
 522                 }
 523                 ast::ItemKind::Enum(ref def, ref generics) => {
 524                     self.format_missing_with_indent(source!(self, item.span).lo());
 525                     self.visit_enum(item.ident, &item.vis, def, generics, item.span);
 526                     self.last_pos = source!(self, item.span).hi();
 527                 }
 528                 ast::ItemKind::Mod(unsafety, ref mod_kind) => {
 529                     self.format_missing_with_indent(source!(self, item.span).lo());
 530                     self.format_mod(mod_kind, unsafety, &item.vis, item.span, item.ident, attrs);
 531                 }
 532                 ast::ItemKind::MacCall(ref mac) => {
 533                     self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
 534                 }
 535                 ast::ItemKind::ForeignMod(ref foreign_mod) => {
 536                     self.format_missing_with_indent(source!(self, item.span).lo());
 537                     self.format_foreign_mod(foreign_mod, item.span);
 538                 }
 539                 ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
 540                     self.visit_static(&StaticParts::from_item(item));
 541                 }
 542                 ast::ItemKind::Fn(ref fn_kind) => {
 543                     let ast::Fn {
 544                         defaultness,
 545                         ref sig,
 546                         ref generics,
 547                         ref body,
 548                     } = **fn_kind;
 549                     if let Some(ref body) = body {
 550                         let inner_attrs = inner_attributes(&item.attrs);
 551                         let fn_ctxt = match sig.header.ext {
 552                             ast::Extern::None => visit::FnCtxt::Free,
 553                             _ => visit::FnCtxt::Foreign,
 554                         };
 555                         self.visit_fn(
 556                             visit::FnKind::Fn(fn_ctxt, item.ident, sig, &item.vis, Some(body)),
 557                             generics,
 558                             &sig.decl,
 559                             item.span,
 560                             defaultness,
 561                             Some(&inner_attrs),
 562                         )
 563                     } else {
 564                         let indent = self.block_indent;
 565                         let rewrite = self.rewrite_required_fn(
 566                             indent, item.ident, sig, &item.vis, generics, item.span,
 567                         );
 568                         self.push_rewrite(item.span, rewrite);
 569                     }
 570                 }
 571                 ast::ItemKind::TyAlias(ref ty_alias) => {
 572                     use ItemVisitorKind::Item;
 573                     self.visit_ty_alias_kind(ty_alias, &Item(item), item.span);
 574                 }
 575                 ast::ItemKind::GlobalAsm(..) => {
 576                     let snippet = Some(self.snippet(item.span).to_owned());
 577                     self.push_rewrite(item.span, snippet);
 578                 }
 579                 ast::ItemKind::MacroDef(ref def) => {
 580                     let rewrite = rewrite_macro_def(
 581                         &self.get_context(),
 582                         self.shape(),
 583                         self.block_indent,
 584                         def,
 585                         item.ident,
 586                         &item.vis,
 587                         item.span,
 588                     );
 589                     self.push_rewrite(item.span, rewrite);
 590                 }
 591             };
 592         }
 593         self.skip_context = skip_context_saved;
 594     }
 595
 596     fn visit_ty_alias_kind(
 597         &mut self,
 598         ty_kind: &ast::TyAlias,
 599         visitor_kind: &ItemVisitorKind<'_>,
 600         span: Span,
 601     ) {
 602         let rewrite = rewrite_type_alias(
 603             ty_kind,
 604             &self.get_context(),
 605             self.block_indent,
 606             visitor_kind,
 607             span,
 608         );
 609         self.push_rewrite(span, rewrite);
 610     }
 611
 612     fn visit_assoc_item(&mut self, visitor_kind: &ItemVisitorKind<'_>) {
 613         use ItemVisitorKind::*;
 614         // TODO(calebcartwright): Not sure the skip spans are correct
 615         let (ai, skip_span, assoc_ctxt) = match visitor_kind {
 616             AssocTraitItem(ai) => (*ai, ai.span(), visit::AssocCtxt::Trait),
 617             AssocImplItem(ai) => (*ai, ai.span, visit::AssocCtxt::Impl),
 618             _ => unreachable!(),
 619         };
 620         skip_out_of_file_lines_range_visitor!(self, ai.span);
 621
 622         if self.visit_attrs(&ai.attrs, ast::AttrStyle::Outer) {
 623             self.push_skipped_with_span(ai.attrs.as_slice(), skip_span, skip_span);
 624             return;
 625         }
 626
 627         // TODO(calebcartwright): consider enabling box_patterns feature gate
 628         match (&ai.kind, visitor_kind) {
 629             (ast::AssocItemKind::Const(..), AssocTraitItem(_)) => {
 630                 self.visit_static(&StaticParts::from_trait_item(ai))
 631             }
 632             (ast::AssocItemKind::Const(..), AssocImplItem(_)) => {
 633                 self.visit_static(&StaticParts::from_impl_item(ai))
 634             }
 635             (ast::AssocItemKind::Fn(ref fn_kind), _) => {
 636                 let ast::Fn {
 637                     defaultness,
 638                     ref sig,
 639                     ref generics,
 640                     ref body,
 641                 } = **fn_kind;
 642                 if let Some(ref body) = body {
 643                     let inner_attrs = inner_attributes(&ai.attrs);
 644                     let fn_ctxt = visit::FnCtxt::Assoc(assoc_ctxt);
 645                     self.visit_fn(
 646                         visit::FnKind::Fn(fn_ctxt, ai.ident, sig, &ai.vis, Some(body)),
 647                         generics,
 648                         &sig.decl,
 649                         ai.span,
 650                         defaultness,
 651                         Some(&inner_attrs),
 652                     );
 653                 } else {
 654                     let indent = self.block_indent;
 655                     let rewrite =
 656                         self.rewrite_required_fn(indent, ai.ident, sig, &ai.vis, generics, ai.span);
 657                     self.push_rewrite(ai.span, rewrite);
 658                 }
 659             }
 660             (ast::AssocItemKind::TyAlias(ref ty_alias), _) => {
 661                 self.visit_ty_alias_kind(ty_alias, visitor_kind, ai.span);
 662             }
 663             (ast::AssocItemKind::MacCall(ref mac), _) => {
 664                 self.visit_mac(mac, Some(ai.ident), MacroPosition::Item);
 665             }
 666             _ => unreachable!(),
 667         }
 668     }
 669
 670     pub(crate) fn visit_trait_item(&mut self, ti: &ast::AssocItem) {
 671         self.visit_assoc_item(&ItemVisitorKind::AssocTraitItem(ti));
 672     }
 673
 674     pub(crate) fn visit_impl_item(&mut self, ii: &ast::AssocItem) {
 675         self.visit_assoc_item(&ItemVisitorKind::AssocImplItem(ii));
 676     }
 677
 678     fn visit_mac(&mut self, mac: &ast::MacCall, ident: Option<symbol::Ident>, pos: MacroPosition) {
 679         skip_out_of_file_lines_range_visitor!(self, mac.span());
 680
 681         // 1 = ;
 682         let shape = self.shape().saturating_sub_width(1);
 683         let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
 684         // As of v638 of the rustc-ap-* crates, the associated span no longer includes
 685         // the trailing semicolon. This determines the correct span to ensure scenarios
 686         // with whitespace between the delimiters and trailing semi (i.e. `foo!(abc)     ;`)
 687         // are formatted correctly.
 688         let (span, rewrite) = match macro_style(mac, &self.get_context()) {
 689             DelimToken::Bracket | DelimToken::Paren if MacroPosition::Item == pos => {
 690                 let search_span = mk_sp(mac.span().hi(), self.snippet_provider.end_pos());
 691                 let hi = self.snippet_provider.span_before(search_span, ";");
 692                 let target_span = mk_sp(mac.span().lo(), hi + BytePos(1));
 693                 let rewrite = rewrite.map(|rw| {
 694                     if !rw.ends_with(';') {
 695                         format!("{};", rw)
 696                     } else {
 697                         rw
 698                     }
 699                 });
 700                 (target_span, rewrite)
 701             }
 702             _ => (mac.span(), rewrite),
 703         };
 704
 705         self.push_rewrite(span, rewrite);
 706     }
 707
 708     pub(crate) fn push_str(&mut self, s: &str) {
 709         self.line_number += count_newlines(s);
 710         self.buffer.push_str(s);
 711     }
 712
 713     #[allow(clippy::needless_pass_by_value)]
 714     fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
 715         if let Some(ref s) = rewrite {
 716             self.push_str(s);
 717         } else {
 718             let snippet = self.snippet(span);
 719             self.push_str(snippet.trim());
 720         }
 721         self.last_pos = source!(self, span).hi();
 722     }
 723
 724     pub(crate) fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
 725         self.format_missing_with_indent(source!(self, span).lo());
 726         self.push_rewrite_inner(span, rewrite);
 727     }
 728
 729     pub(crate) fn push_skipped_with_span(
 730         &mut self,
 731         attrs: &[ast::Attribute],
 732         item_span: Span,
 733         main_span: Span,
 734     ) {
 735         self.format_missing_with_indent(source!(self, item_span).lo());
 736         // do not take into account the lines with attributes as part of the skipped range
 737         let attrs_end = attrs
 738             .iter()
 739             .map(|attr| self.parse_sess.line_of_byte_pos(attr.span.hi()))
 740             .max()
 741             .unwrap_or(1);
 742         let first_line = self.parse_sess.line_of_byte_pos(main_span.lo());
 743         // Statement can start after some newlines and/or spaces
 744         // or it can be on the same line as the last attribute.
 745         // So here we need to take a minimum between the two.
 746         let lo = std::cmp::min(attrs_end + 1, first_line);
 747         self.push_rewrite_inner(item_span, None);
 748         let hi = self.line_number + 1;
 749         self.skipped_range.borrow_mut().push((lo, hi));
 750     }
 751
 752     pub(crate) fn from_context(ctx: &'a RewriteContext<'_>) -> FmtVisitor<'a> {
 753         let mut visitor = FmtVisitor::from_parse_sess(
 754             ctx.parse_sess,
 755             ctx.config,
 756             ctx.snippet_provider,
 757             ctx.report.clone(),
 758             ctx.memoize.clone(),
 759         );
 760         visitor.skip_context.update(ctx.skip_context.clone());
 761         visitor.set_parent_context(ctx);
 762         visitor
 763     }
 764
 765     pub(crate) fn from_parse_sess(
 766         parse_session: &'a ParseSess,
 767         config: &'a Config,
 768         snippet_provider: &'a SnippetProvider,
 769         report: FormatReport,
 770         memoize: Memoize,
 771     ) -> FmtVisitor<'a> {
 772         FmtVisitor {
 773             parent_context: None,
 774             parse_sess: parse_session,
 775             memoize,
 776             buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
 777             last_pos: BytePos(0),
 778             block_indent: Indent::empty(),
 779             config,
 780             is_if_else_block: false,
 781             snippet_provider,
 782             line_number: 0,
 783             skipped_range: Rc::new(RefCell::new(vec![])),
 784             is_macro_def: false,
 785             macro_rewrite_failure: false,
 786             report,
 787             skip_context: Default::default(),
 788         }
 789     }
 790
 791     pub(crate) fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
 792         self.snippet_provider.span_to_snippet(span)
 793     }
 794
 795     pub(crate) fn snippet(&'b self, span: Span) -> &'a str {
 796         self.opt_snippet(span).unwrap()
 797     }
 798
 799     // Returns true if we should skip the following item.
 800     pub(crate) fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
 801         for attr in attrs {
 802             if attr.has_name(depr_skip_annotation()) {
 803                 let file_name = self.parse_sess.span_to_filename(attr.span);
 804                 self.report.append(
 805                     file_name,
 806                     vec![FormattingError::from_span(
 807                         attr.span,
 808                         self.parse_sess,
 809                         ErrorKind::DeprecatedAttr,
 810                     )],
 811                 );
 812             } else {
 813                 match &attr.kind {
 814                     ast::AttrKind::Normal(ref attribute_item, _)
 815                         if self.is_unknown_rustfmt_attr(&attribute_item.path.segments) =>
 816                     {
 817                         let file_name = self.parse_sess.span_to_filename(attr.span);
 818                         self.report.append(
 819                             file_name,
 820                             vec![FormattingError::from_span(
 821                                 attr.span,
 822                                 self.parse_sess,
 823                                 ErrorKind::BadAttr,
 824                             )],
 825                         );
 826                     }
 827                     _ => (),
 828                 }
 829             }
 830         }
 831         if contains_skip(attrs) {
 832             return true;
 833         }
 834
 835         let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
 836         if attrs.is_empty() {
 837             return false;
 838         }
 839
 840         let rewrite = attrs.rewrite(&self.get_context(), self.shape());
 841         let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
 842         self.push_rewrite(span, rewrite);
 843
 844         false
 845     }
 846
 847     fn is_unknown_rustfmt_attr(&self, segments: &[ast::PathSegment]) -> bool {
 848         if segments[0].ident.to_string() != "rustfmt" {
 849             return false;
 850         }
 851         !is_skip_attr(segments)
 852     }
 853
 854     fn walk_mod_items(&mut self, items: &[rustc_ast::ptr::P<ast::Item>]) {
 855         self.visit_items_with_reordering(&ptr_vec_to_ref_vec(items));
 856     }
 857
 858     fn walk_stmts(&mut self, stmts: &[Stmt<'_>], include_current_empty_semi: bool) {
 859         if stmts.is_empty() {
 860             return;
 861         }
 862
 863         // Extract leading `use ...;`.
 864         let items: Vec<_> = stmts
 865             .iter()
 866             .take_while(|stmt| stmt.to_item().map_or(false, is_use_item))
 867             .filter_map(|stmt| stmt.to_item())
 868             .collect();
 869
 870         if items.is_empty() {
 871             self.visit_stmt(&stmts[0], include_current_empty_semi);
 872
 873             // FIXME(calebcartwright 2021-01-03) - This exists strictly to maintain legacy
 874             // formatting where rustfmt would preserve redundant semicolons on Items in a
 875             // statement position.
 876             //
 877             // Starting in rustc-ap-* v692 (~2020-12-01) the rustc parser now parses this as
 878             // two separate statements (Item and Empty kinds), whereas before it was parsed as
 879             // a single statement with the statement's span including the redundant semicolon.
 880             //
 881             // rustfmt typically tosses unnecessary/redundant semicolons, and eventually we
 882             // should toss these as well, but doing so at this time would
 883             // break the Stability Guarantee
 884             // N.B. This could be updated to utilize the version gates.
 885             let include_next_empty = if stmts.len() > 1 {
 886                 matches!(
 887                     (&stmts[0].as_ast_node().kind, &stmts[1].as_ast_node().kind),
 888                     (ast::StmtKind::Item(_), ast::StmtKind::Empty)
 889                 )
 890             } else {
 891                 false
 892             };
 893
 894             self.walk_stmts(&stmts[1..], include_next_empty);
 895         } else {
 896             self.visit_items_with_reordering(&items);
 897             self.walk_stmts(&stmts[items.len()..], false);
 898         }
 899     }
 900
 901     fn walk_block_stmts(&mut self, b: &ast::Block) {
 902         self.walk_stmts(&Stmt::from_ast_nodes(b.stmts.iter()), false)
 903     }
 904
 905     fn format_mod(
 906         &mut self,
 907         mod_kind: &ast::ModKind,
 908         unsafety: ast::Unsafe,
 909         vis: &ast::Visibility,
 910         s: Span,
 911         ident: symbol::Ident,
 912         attrs: &[ast::Attribute],
 913     ) {
 914         let vis_str = utils::format_visibility(&self.get_context(), vis);
 915         self.push_str(&*vis_str);
 916         self.push_str(format_unsafety(unsafety));
 917         self.push_str("mod ");
 918         // Calling `to_owned()` to work around borrow checker.
 919         let ident_str = rewrite_ident(&self.get_context(), ident).to_owned();
 920         self.push_str(&ident_str);
 921
 922         if let ast::ModKind::Loaded(ref items, ast::Inline::Yes, ref spans) = mod_kind {
 923             let ast::ModSpans {
 924                 inner_span,
 925                 inject_use_span: _,
 926             } = *spans;
 927             match self.config.brace_style() {
 928                 BraceStyle::AlwaysNextLine => {
 929                     let indent_str = self.block_indent.to_string_with_newline(self.config);
 930                     self.push_str(&indent_str);
 931                     self.push_str("{");
 932                 }
 933                 _ => self.push_str(" {"),
 934             }
 935             // Hackery to account for the closing }.
 936             let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
 937             let body_snippet =
 938                 self.snippet(mk_sp(mod_lo, source!(self, inner_span).hi() - BytePos(1)));
 939             let body_snippet = body_snippet.trim();
 940             if body_snippet.is_empty() {
 941                 self.push_str("}");
 942             } else {
 943                 self.last_pos = mod_lo;
 944                 self.block_indent = self.block_indent.block_indent(self.config);
 945                 self.visit_attrs(attrs, ast::AttrStyle::Inner);
 946                 self.walk_mod_items(items);
 947                 let missing_span = self.next_span(inner_span.hi() - BytePos(1));
 948                 self.close_block(missing_span, false);
 949             }
 950             self.last_pos = source!(self, inner_span).hi();
 951         } else {
 952             self.push_str(";");
 953             self.last_pos = source!(self, s).hi();
 954         }
 955     }
 956
 957     pub(crate) fn format_separate_mod(&mut self, m: &Module<'_>, end_pos: BytePos) {
 958         self.block_indent = Indent::empty();
 959         let skipped = self.visit_attrs(m.attrs(), ast::AttrStyle::Inner);
 960         assert!(
 961             !skipped,
 962             "Skipping module must be handled before reaching this line."
 963         );
 964         self.walk_mod_items(&m.items);
 965         self.format_missing_with_indent(end_pos);
 966     }
 967
 968     pub(crate) fn skip_empty_lines(&mut self, end_pos: BytePos) {
 969         while let Some(pos) = self
 970             .snippet_provider
 971             .opt_span_after(self.next_span(end_pos), "\n")
 972         {
 973             if let Some(snippet) = self.opt_snippet(self.next_span(pos)) {
 974                 if snippet.trim().is_empty() {
 975                     self.last_pos = pos;
 976                 } else {
 977                     return;
 978                 }
 979             }
 980         }
 981     }
 982
 983     pub(crate) fn with_context<F>(&mut self, f: F) -> Option<String>
 984     where
 985         F: Fn(&RewriteContext<'_>) -> Option<String>,
 986     {
 987         let context = self.get_context();
 988         let result = f(&context);
 989
 990         self.macro_rewrite_failure |= context.macro_rewrite_failure.get();
 991         result
 992     }
 993
 994     pub(crate) fn get_context(&self) -> RewriteContext<'_> {
 995         RewriteContext {
 996             parse_sess: self.parse_sess,
 997             config: self.config,
 998             memoize: self.memoize.clone(),
 999             inside_macro: Rc::new(Cell::new(false)),
1000             use_block: Cell::new(false),
1001             is_if_else_block: Cell::new(false),
1002             force_one_line_chain: Cell::new(false),
1003             snippet_provider: self.snippet_provider,
1004             macro_rewrite_failure: Cell::new(false),
1005             is_macro_def: self.is_macro_def,
1006             report: self.report.clone(),
1007             skip_context: self.skip_context.clone(),
1008             skipped_range: self.skipped_range.clone(),
1009         }
1010     }
1011 }