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