src/librustc_expand/expand.rs

   1 use crate::base::*;
   2 use crate::config::StripUnconfigured;
   3 use crate::hygiene::{ExpnData, ExpnId, ExpnKind, SyntaxContext};
   4 use crate::mbe::macro_rules::annotate_err_with_kind;
   5 use crate::placeholders::{placeholder, PlaceholderExpander};
   6 use crate::proc_macro::collect_derives;
   7
   8 use rustc_ast_pretty::pprust;
   9 use rustc_attr::{self as attr, is_builtin_attr, HasAttrs};
  10 use rustc_data_structures::sync::Lrc;
  11 use rustc_errors::{Applicability, FatalError, PResult};
  12 use rustc_feature::Features;
  13 use rustc_parse::configure;
  14 use rustc_parse::parser::Parser;
  15 use rustc_parse::validate_attr;
  16 use rustc_parse::DirectoryOwnership;
  17 use rustc_session::parse::{feature_err, ParseSess};
  18 use rustc_span::source_map::respan;
  19 use rustc_span::symbol::{sym, Symbol};
  20 use rustc_span::{FileName, Span, DUMMY_SP};
  21 use syntax::ast::{self, AttrItem, Block, Ident, LitKind, NodeId, PatKind, Path};
  22 use syntax::ast::{ItemKind, MacArgs, MacStmtStyle, StmtKind};
  23 use syntax::mut_visit::*;
  24 use syntax::ptr::P;
  25 use syntax::token;
  26 use syntax::tokenstream::{TokenStream, TokenTree};
  27 use syntax::util::map_in_place::MapInPlace;
  28 use syntax::visit::{self, Visitor};
  29
  30 use smallvec::{smallvec, SmallVec};
  31 use std::io::ErrorKind;
  32 use std::ops::DerefMut;
  33 use std::path::PathBuf;
  34 use std::rc::Rc;
  35 use std::{iter, mem, slice};
  36
  37 macro_rules! ast_fragments {
  38     (
  39         $($Kind:ident($AstTy:ty) {
  40             $kind_name:expr;
  41             $(one fn $mut_visit_ast:ident; fn $visit_ast:ident;)?
  42             $(many fn $flat_map_ast_elt:ident; fn $visit_ast_elt:ident;)?
  43             fn $make_ast:ident;
  44         })*
  45     ) => {
  46         /// A fragment of AST that can be produced by a single macro expansion.
  47         /// Can also serve as an input and intermediate result for macro expansion operations.
  48         pub enum AstFragment {
  49             OptExpr(Option<P<ast::Expr>>),
  50             $($Kind($AstTy),)*
  51         }
  52
  53         /// "Discriminant" of an AST fragment.
  54         #[derive(Copy, Clone, PartialEq, Eq)]
  55         pub enum AstFragmentKind {
  56             OptExpr,
  57             $($Kind,)*
  58         }
  59
  60         impl AstFragmentKind {
  61             pub fn name(self) -> &'static str {
  62                 match self {
  63                     AstFragmentKind::OptExpr => "expression",
  64                     $(AstFragmentKind::$Kind => $kind_name,)*
  65                 }
  66             }
  67
  68             fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
  69                 match self {
  70                     AstFragmentKind::OptExpr =>
  71                         result.make_expr().map(Some).map(AstFragment::OptExpr),
  72                     $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
  73                 }
  74             }
  75         }
  76
  77         impl AstFragment {
  78             pub fn add_placeholders(&mut self, placeholders: &[NodeId]) {
  79                 if placeholders.is_empty() {
  80                     return;
  81                 }
  82                 match self {
  83                     $($(AstFragment::$Kind(ast) => ast.extend(placeholders.iter().flat_map(|id| {
  84                         // We are repeating through arguments with `many`, to do that we have to
  85                         // mention some macro variable from those arguments even if it's not used.
  86                         macro _repeating($flat_map_ast_elt) {}
  87                         placeholder(AstFragmentKind::$Kind, *id, None).$make_ast()
  88                     })),)?)*
  89                     _ => panic!("unexpected AST fragment kind")
  90                 }
  91             }
  92
  93             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  94                 match self {
  95                     AstFragment::OptExpr(expr) => expr,
  96                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
  97                 }
  98             }
  99
 100             $(pub fn $make_ast(self) -> $AstTy {
 101                 match self {
 102                     AstFragment::$Kind(ast) => ast,
 103                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
 104                 }
 105             })*
 106
 107             pub fn mut_visit_with<F: MutVisitor>(&mut self, vis: &mut F) {
 108                 match self {
 109                     AstFragment::OptExpr(opt_expr) => {
 110                         visit_clobber(opt_expr, |opt_expr| {
 111                             if let Some(expr) = opt_expr {
 112                                 vis.filter_map_expr(expr)
 113                             } else {
 114                                 None
 115                             }
 116                         });
 117                     }
 118                     $($(AstFragment::$Kind(ast) => vis.$mut_visit_ast(ast),)?)*
 119                     $($(AstFragment::$Kind(ast) =>
 120                         ast.flat_map_in_place(|ast| vis.$flat_map_ast_elt(ast)),)?)*
 121                 }
 122             }
 123
 124             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
 125                 match *self {
 126                     AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
 127                     AstFragment::OptExpr(None) => {}
 128                     $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)?)*
 129                     $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
 130                         visitor.$visit_ast_elt(ast_elt);
 131                     })?)*
 132                 }
 133             }
 134         }
 135
 136         impl<'a> MacResult for crate::mbe::macro_rules::ParserAnyMacro<'a> {
 137             $(fn $make_ast(self: Box<crate::mbe::macro_rules::ParserAnyMacro<'a>>)
 138                            -> Option<$AstTy> {
 139                 Some(self.make(AstFragmentKind::$Kind).$make_ast())
 140             })*
 141         }
 142     }
 143 }
 144
 145 ast_fragments! {
 146     Expr(P<ast::Expr>) { "expression"; one fn visit_expr; fn visit_expr; fn make_expr; }
 147     Pat(P<ast::Pat>) { "pattern"; one fn visit_pat; fn visit_pat; fn make_pat; }
 148     Ty(P<ast::Ty>) { "type"; one fn visit_ty; fn visit_ty; fn make_ty; }
 149     Stmts(SmallVec<[ast::Stmt; 1]>) {
 150         "statement"; many fn flat_map_stmt; fn visit_stmt; fn make_stmts;
 151     }
 152     Items(SmallVec<[P<ast::Item>; 1]>) {
 153         "item"; many fn flat_map_item; fn visit_item; fn make_items;
 154     }
 155     TraitItems(SmallVec<[P<ast::AssocItem>; 1]>) {
 156         "trait item"; many fn flat_map_trait_item; fn visit_trait_item; fn make_trait_items;
 157     }
 158     ImplItems(SmallVec<[P<ast::AssocItem>; 1]>) {
 159         "impl item"; many fn flat_map_impl_item; fn visit_impl_item; fn make_impl_items;
 160     }
 161     ForeignItems(SmallVec<[P<ast::ForeignItem>; 1]>) {
 162         "foreign item";
 163         many fn flat_map_foreign_item;
 164         fn visit_foreign_item;
 165         fn make_foreign_items;
 166     }
 167     Arms(SmallVec<[ast::Arm; 1]>) {
 168         "match arm"; many fn flat_map_arm; fn visit_arm; fn make_arms;
 169     }
 170     Fields(SmallVec<[ast::Field; 1]>) {
 171         "field expression"; many fn flat_map_field; fn visit_field; fn make_fields;
 172     }
 173     FieldPats(SmallVec<[ast::FieldPat; 1]>) {
 174         "field pattern";
 175         many fn flat_map_field_pattern;
 176         fn visit_field_pattern;
 177         fn make_field_patterns;
 178     }
 179     GenericParams(SmallVec<[ast::GenericParam; 1]>) {
 180         "generic parameter";
 181         many fn flat_map_generic_param;
 182         fn visit_generic_param;
 183         fn make_generic_params;
 184     }
 185     Params(SmallVec<[ast::Param; 1]>) {
 186         "function parameter"; many fn flat_map_param; fn visit_param; fn make_params;
 187     }
 188     StructFields(SmallVec<[ast::StructField; 1]>) {
 189         "field";
 190         many fn flat_map_struct_field;
 191         fn visit_struct_field;
 192         fn make_struct_fields;
 193     }
 194     Variants(SmallVec<[ast::Variant; 1]>) {
 195         "variant"; many fn flat_map_variant; fn visit_variant; fn make_variants;
 196     }
 197 }
 198
 199 impl AstFragmentKind {
 200     fn dummy(self, span: Span) -> AstFragment {
 201         self.make_from(DummyResult::any(span)).expect("couldn't create a dummy AST fragment")
 202     }
 203
 204     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(
 205         self,
 206         items: I,
 207     ) -> AstFragment {
 208         let mut items = items.into_iter();
 209         match self {
 210             AstFragmentKind::Arms => {
 211                 AstFragment::Arms(items.map(Annotatable::expect_arm).collect())
 212             }
 213             AstFragmentKind::Fields => {
 214                 AstFragment::Fields(items.map(Annotatable::expect_field).collect())
 215             }
 216             AstFragmentKind::FieldPats => {
 217                 AstFragment::FieldPats(items.map(Annotatable::expect_field_pattern).collect())
 218             }
 219             AstFragmentKind::GenericParams => {
 220                 AstFragment::GenericParams(items.map(Annotatable::expect_generic_param).collect())
 221             }
 222             AstFragmentKind::Params => {
 223                 AstFragment::Params(items.map(Annotatable::expect_param).collect())
 224             }
 225             AstFragmentKind::StructFields => {
 226                 AstFragment::StructFields(items.map(Annotatable::expect_struct_field).collect())
 227             }
 228             AstFragmentKind::Variants => {
 229                 AstFragment::Variants(items.map(Annotatable::expect_variant).collect())
 230             }
 231             AstFragmentKind::Items => {
 232                 AstFragment::Items(items.map(Annotatable::expect_item).collect())
 233             }
 234             AstFragmentKind::ImplItems => {
 235                 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect())
 236             }
 237             AstFragmentKind::TraitItems => {
 238                 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect())
 239             }
 240             AstFragmentKind::ForeignItems => {
 241                 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect())
 242             }
 243             AstFragmentKind::Stmts => {
 244                 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect())
 245             }
 246             AstFragmentKind::Expr => AstFragment::Expr(
 247                 items.next().expect("expected exactly one expression").expect_expr(),
 248             ),
 249             AstFragmentKind::OptExpr => {
 250                 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr))
 251             }
 252             AstFragmentKind::Pat | AstFragmentKind::Ty => {
 253                 panic!("patterns and types aren't annotatable")
 254             }
 255         }
 256     }
 257 }
 258
 259 pub struct Invocation {
 260     pub kind: InvocationKind,
 261     pub fragment_kind: AstFragmentKind,
 262     pub expansion_data: ExpansionData,
 263 }
 264
 265 pub enum InvocationKind {
 266     Bang {
 267         mac: ast::Mac,
 268         span: Span,
 269     },
 270     Attr {
 271         attr: ast::Attribute,
 272         item: Annotatable,
 273         // Required for resolving derive helper attributes.
 274         derives: Vec<Path>,
 275         // We temporarily report errors for attribute macros placed after derives
 276         after_derive: bool,
 277     },
 278     Derive {
 279         path: Path,
 280         item: Annotatable,
 281     },
 282     /// "Invocation" that contains all derives from an item,
 283     /// broken into multiple `Derive` invocations when expanded.
 284     /// FIXME: Find a way to remove it.
 285     DeriveContainer {
 286         derives: Vec<Path>,
 287         item: Annotatable,
 288     },
 289 }
 290
 291 impl InvocationKind {
 292     fn placeholder_visibility(&self) -> Option<ast::Visibility> {
 293         // HACK: For unnamed fields placeholders should have the same visibility as the actual
 294         // fields because for tuple structs/variants resolve determines visibilities of their
 295         // constructor using these field visibilities before attributes on them are are expanded.
 296         // The assumption is that the attribute expansion cannot change field visibilities,
 297         // and it holds because only inert attributes are supported in this position.
 298         match self {
 299             InvocationKind::Attr { item: Annotatable::StructField(field), .. }
 300             | InvocationKind::Derive { item: Annotatable::StructField(field), .. }
 301             | InvocationKind::DeriveContainer { item: Annotatable::StructField(field), .. }
 302                 if field.ident.is_none() =>
 303             {
 304                 Some(field.vis.clone())
 305             }
 306             _ => None,
 307         }
 308     }
 309 }
 310
 311 impl Invocation {
 312     pub fn span(&self) -> Span {
 313         match &self.kind {
 314             InvocationKind::Bang { span, .. } => *span,
 315             InvocationKind::Attr { attr, .. } => attr.span,
 316             InvocationKind::Derive { path, .. } => path.span,
 317             InvocationKind::DeriveContainer { item, .. } => item.span(),
 318         }
 319     }
 320 }
 321
 322 pub struct MacroExpander<'a, 'b> {
 323     pub cx: &'a mut ExtCtxt<'b>,
 324     monotonic: bool, // cf. `cx.monotonic_expander()`
 325 }
 326
 327 impl<'a, 'b> MacroExpander<'a, 'b> {
 328     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 329         MacroExpander { cx, monotonic }
 330     }
 331
 332     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 333         let mut module = ModuleData {
 334             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 335             directory: match self.cx.source_map().span_to_unmapped_path(krate.span) {
 336                 FileName::Real(path) => path,
 337                 other => PathBuf::from(other.to_string()),
 338             },
 339         };
 340         module.directory.pop();
 341         self.cx.root_path = module.directory.clone();
 342         self.cx.current_expansion.module = Rc::new(module);
 343
 344         let orig_mod_span = krate.module.inner;
 345
 346         let krate_item = AstFragment::Items(smallvec![P(ast::Item {
 347             attrs: krate.attrs,
 348             span: krate.span,
 349             kind: ast::ItemKind::Mod(krate.module),
 350             ident: Ident::invalid(),
 351             id: ast::DUMMY_NODE_ID,
 352             vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
 353             tokens: None,
 354         })]);
 355
 356         match self.fully_expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
 357             Some(ast::Item { attrs, kind: ast::ItemKind::Mod(module), .. }) => {
 358                 krate.attrs = attrs;
 359                 krate.module = module;
 360             }
 361             None => {
 362                 // Resolution failed so we return an empty expansion
 363                 krate.attrs = vec![];
 364                 krate.module = ast::Mod { inner: orig_mod_span, items: vec![], inline: true };
 365             }
 366             _ => unreachable!(),
 367         };
 368         self.cx.trace_macros_diag();
 369         krate
 370     }
 371
 372     // Recursively expand all macro invocations in this AST fragment.
 373     pub fn fully_expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
 374         let orig_expansion_data = self.cx.current_expansion.clone();
 375         self.cx.current_expansion.depth = 0;
 376
 377         // Collect all macro invocations and replace them with placeholders.
 378         let (mut fragment_with_placeholders, mut invocations) =
 379             self.collect_invocations(input_fragment, &[]);
 380
 381         // Optimization: if we resolve all imports now,
 382         // we'll be able to immediately resolve most of imported macros.
 383         self.resolve_imports();
 384
 385         // Resolve paths in all invocations and produce output expanded fragments for them, but
 386         // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
 387         // The output fragments also go through expansion recursively until no invocations are left.
 388         // Unresolved macros produce dummy outputs as a recovery measure.
 389         invocations.reverse();
 390         let mut expanded_fragments = Vec::new();
 391         let mut undetermined_invocations = Vec::new();
 392         let (mut progress, mut force) = (false, !self.monotonic);
 393         loop {
 394             let invoc = if let Some(invoc) = invocations.pop() {
 395                 invoc
 396             } else {
 397                 self.resolve_imports();
 398                 if undetermined_invocations.is_empty() {
 399                     break;
 400                 }
 401                 invocations = mem::take(&mut undetermined_invocations);
 402                 force = !mem::replace(&mut progress, false);
 403                 continue;
 404             };
 405
 406             let eager_expansion_root =
 407                 if self.monotonic { invoc.expansion_data.id } else { orig_expansion_data.id };
 408             let res = match self.cx.resolver.resolve_macro_invocation(
 409                 &invoc,
 410                 eager_expansion_root,
 411                 force,
 412             ) {
 413                 Ok(res) => res,
 414                 Err(Indeterminate) => {
 415                     undetermined_invocations.push(invoc);
 416                     continue;
 417                 }
 418             };
 419
 420             progress = true;
 421             let ExpansionData { depth, id: expn_id, .. } = invoc.expansion_data;
 422             self.cx.current_expansion = invoc.expansion_data.clone();
 423
 424             // FIXME(jseyfried): Refactor out the following logic
 425             let (expanded_fragment, new_invocations) = match res {
 426                 InvocationRes::Single(ext) => {
 427                     let fragment = self.expand_invoc(invoc, &ext.kind);
 428                     self.collect_invocations(fragment, &[])
 429                 }
 430                 InvocationRes::DeriveContainer(_exts) => {
 431                     // FIXME: Consider using the derive resolutions (`_exts`) immediately,
 432                     // instead of enqueuing the derives to be resolved again later.
 433                     let (derives, item) = match invoc.kind {
 434                         InvocationKind::DeriveContainer { derives, item } => (derives, item),
 435                         _ => unreachable!(),
 436                     };
 437                     if !item.derive_allowed() {
 438                         let attr = attr::find_by_name(item.attrs(), sym::derive)
 439                             .expect("`derive` attribute should exist");
 440                         let span = attr.span;
 441                         let mut err = self.cx.struct_span_err(
 442                             span,
 443                             "`derive` may only be applied to structs, enums and unions",
 444                         );
 445                         if let ast::AttrStyle::Inner = attr.style {
 446                             let trait_list = derives
 447                                 .iter()
 448                                 .map(|t| pprust::path_to_string(t))
 449                                 .collect::<Vec<_>>();
 450                             let suggestion = format!("#[derive({})]", trait_list.join(", "));
 451                             err.span_suggestion(
 452                                 span,
 453                                 "try an outer attribute",
 454                                 suggestion,
 455                                 // We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
 456                                 Applicability::MaybeIncorrect,
 457                             );
 458                         }
 459                         err.emit();
 460                     }
 461
 462                     let mut item = self.fully_configure(item);
 463                     item.visit_attrs(|attrs| attrs.retain(|a| !a.has_name(sym::derive)));
 464
 465                     let mut derive_placeholders = Vec::with_capacity(derives.len());
 466                     invocations.reserve(derives.len());
 467                     for path in derives {
 468                         let expn_id = ExpnId::fresh(None);
 469                         derive_placeholders.push(NodeId::placeholder_from_expn_id(expn_id));
 470                         invocations.push(Invocation {
 471                             kind: InvocationKind::Derive { path, item: item.clone() },
 472                             fragment_kind: invoc.fragment_kind,
 473                             expansion_data: ExpansionData {
 474                                 id: expn_id,
 475                                 ..invoc.expansion_data.clone()
 476                             },
 477                         });
 478                     }
 479                     let fragment =
 480                         invoc.fragment_kind.expect_from_annotatables(::std::iter::once(item));
 481                     self.collect_invocations(fragment, &derive_placeholders)
 482                 }
 483             };
 484
 485             if expanded_fragments.len() < depth {
 486                 expanded_fragments.push(Vec::new());
 487             }
 488             expanded_fragments[depth - 1].push((expn_id, expanded_fragment));
 489             if !self.cx.ecfg.single_step {
 490                 invocations.extend(new_invocations.into_iter().rev());
 491             }
 492         }
 493
 494         self.cx.current_expansion = orig_expansion_data;
 495
 496         // Finally incorporate all the expanded macros into the input AST fragment.
 497         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 498         while let Some(expanded_fragments) = expanded_fragments.pop() {
 499             for (expn_id, expanded_fragment) in expanded_fragments.into_iter().rev() {
 500                 placeholder_expander
 501                     .add(NodeId::placeholder_from_expn_id(expn_id), expanded_fragment);
 502             }
 503         }
 504         fragment_with_placeholders.mut_visit_with(&mut placeholder_expander);
 505         fragment_with_placeholders
 506     }
 507
 508     fn resolve_imports(&mut self) {
 509         if self.monotonic {
 510             self.cx.resolver.resolve_imports();
 511         }
 512     }
 513
 514     /// Collects all macro invocations reachable at this time in this AST fragment, and replace
 515     /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
 516     /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
 517     /// prepares data for resolving paths of macro invocations.
 518     fn collect_invocations(
 519         &mut self,
 520         mut fragment: AstFragment,
 521         extra_placeholders: &[NodeId],
 522     ) -> (AstFragment, Vec<Invocation>) {
 523         // Resolve `$crate`s in the fragment for pretty-printing.
 524         self.cx.resolver.resolve_dollar_crates();
 525
 526         let invocations = {
 527             let mut collector = InvocationCollector {
 528                 cfg: StripUnconfigured {
 529                     sess: self.cx.parse_sess,
 530                     features: self.cx.ecfg.features,
 531                 },
 532                 cx: self.cx,
 533                 invocations: Vec::new(),
 534                 monotonic: self.monotonic,
 535             };
 536             fragment.mut_visit_with(&mut collector);
 537             fragment.add_placeholders(extra_placeholders);
 538             collector.invocations
 539         };
 540
 541         if self.monotonic {
 542             self.cx
 543                 .resolver
 544                 .visit_ast_fragment_with_placeholders(self.cx.current_expansion.id, &fragment);
 545         }
 546
 547         (fragment, invocations)
 548     }
 549
 550     fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
 551         let mut cfg =
 552             StripUnconfigured { sess: self.cx.parse_sess, features: self.cx.ecfg.features };
 553         // Since the item itself has already been configured by the InvocationCollector,
 554         // we know that fold result vector will contain exactly one element
 555         match item {
 556             Annotatable::Item(item) => Annotatable::Item(cfg.flat_map_item(item).pop().unwrap()),
 557             Annotatable::TraitItem(item) => {
 558                 Annotatable::TraitItem(cfg.flat_map_trait_item(item).pop().unwrap())
 559             }
 560             Annotatable::ImplItem(item) => {
 561                 Annotatable::ImplItem(cfg.flat_map_impl_item(item).pop().unwrap())
 562             }
 563             Annotatable::ForeignItem(item) => {
 564                 Annotatable::ForeignItem(cfg.flat_map_foreign_item(item).pop().unwrap())
 565             }
 566             Annotatable::Stmt(stmt) => {
 567                 Annotatable::Stmt(stmt.map(|stmt| cfg.flat_map_stmt(stmt).pop().unwrap()))
 568             }
 569             Annotatable::Expr(mut expr) => Annotatable::Expr({
 570                 cfg.visit_expr(&mut expr);
 571                 expr
 572             }),
 573             Annotatable::Arm(arm) => Annotatable::Arm(cfg.flat_map_arm(arm).pop().unwrap()),
 574             Annotatable::Field(field) => {
 575                 Annotatable::Field(cfg.flat_map_field(field).pop().unwrap())
 576             }
 577             Annotatable::FieldPat(fp) => {
 578                 Annotatable::FieldPat(cfg.flat_map_field_pattern(fp).pop().unwrap())
 579             }
 580             Annotatable::GenericParam(param) => {
 581                 Annotatable::GenericParam(cfg.flat_map_generic_param(param).pop().unwrap())
 582             }
 583             Annotatable::Param(param) => {
 584                 Annotatable::Param(cfg.flat_map_param(param).pop().unwrap())
 585             }
 586             Annotatable::StructField(sf) => {
 587                 Annotatable::StructField(cfg.flat_map_struct_field(sf).pop().unwrap())
 588             }
 589             Annotatable::Variant(v) => Annotatable::Variant(cfg.flat_map_variant(v).pop().unwrap()),
 590         }
 591     }
 592
 593     fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtensionKind) -> AstFragment {
 594         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
 595             let expn_data = self.cx.current_expansion.id.expn_data();
 596             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
 597             let mut err = self.cx.struct_span_err(
 598                 expn_data.call_site,
 599                 &format!("recursion limit reached while expanding `{}`", expn_data.kind.descr()),
 600             );
 601             err.help(&format!(
 602                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
 603                 suggested_limit
 604             ));
 605             err.emit();
 606             self.cx.trace_macros_diag();
 607             FatalError.raise();
 608         }
 609
 610         let (fragment_kind, span) = (invoc.fragment_kind, invoc.span());
 611         match invoc.kind {
 612             InvocationKind::Bang { mac, .. } => match ext {
 613                 SyntaxExtensionKind::Bang(expander) => {
 614                     self.gate_proc_macro_expansion_kind(span, fragment_kind);
 615                     let tok_result = expander.expand(self.cx, span, mac.args.inner_tokens());
 616                     self.parse_ast_fragment(tok_result, fragment_kind, &mac.path, span)
 617                 }
 618                 SyntaxExtensionKind::LegacyBang(expander) => {
 619                     let prev = self.cx.current_expansion.prior_type_ascription;
 620                     self.cx.current_expansion.prior_type_ascription = mac.prior_type_ascription;
 621                     let tok_result = expander.expand(self.cx, span, mac.args.inner_tokens());
 622                     let result = if let Some(result) = fragment_kind.make_from(tok_result) {
 623                         result
 624                     } else {
 625                         let msg = format!(
 626                             "non-{kind} macro in {kind} position: {path}",
 627                             kind = fragment_kind.name(),
 628                             path = pprust::path_to_string(&mac.path),
 629                         );
 630                         self.cx.span_err(span, &msg);
 631                         self.cx.trace_macros_diag();
 632                         fragment_kind.dummy(span)
 633                     };
 634                     self.cx.current_expansion.prior_type_ascription = prev;
 635                     result
 636                 }
 637                 _ => unreachable!(),
 638             },
 639             InvocationKind::Attr { attr, mut item, .. } => match ext {
 640                 SyntaxExtensionKind::Attr(expander) => {
 641                     self.gate_proc_macro_input(&item);
 642                     self.gate_proc_macro_attr_item(span, &item);
 643                     let item_tok = TokenTree::token(
 644                         token::Interpolated(Lrc::new(match item {
 645                             Annotatable::Item(item) => token::NtItem(item),
 646                             Annotatable::TraitItem(item) => token::NtTraitItem(item),
 647                             Annotatable::ImplItem(item) => token::NtImplItem(item),
 648                             Annotatable::ForeignItem(item) => token::NtForeignItem(item),
 649                             Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
 650                             Annotatable::Expr(expr) => token::NtExpr(expr),
 651                             Annotatable::Arm(..)
 652                             | Annotatable::Field(..)
 653                             | Annotatable::FieldPat(..)
 654                             | Annotatable::GenericParam(..)
 655                             | Annotatable::Param(..)
 656                             | Annotatable::StructField(..)
 657                             | Annotatable::Variant(..) => panic!("unexpected annotatable"),
 658                         })),
 659                         DUMMY_SP,
 660                     )
 661                     .into();
 662                     let item = attr.unwrap_normal_item();
 663                     if let MacArgs::Eq(..) = item.args {
 664                         self.cx.span_err(span, "key-value macro attributes are not supported");
 665                     }
 666                     let tok_result =
 667                         expander.expand(self.cx, span, item.args.inner_tokens(), item_tok);
 668                     self.parse_ast_fragment(tok_result, fragment_kind, &item.path, span)
 669                 }
 670                 SyntaxExtensionKind::LegacyAttr(expander) => {
 671                     match validate_attr::parse_meta(self.cx.parse_sess, &attr) {
 672                         Ok(meta) => {
 673                             let item = expander.expand(self.cx, span, &meta, item);
 674                             fragment_kind.expect_from_annotatables(item)
 675                         }
 676                         Err(mut err) => {
 677                             err.emit();
 678                             fragment_kind.dummy(span)
 679                         }
 680                     }
 681                 }
 682                 SyntaxExtensionKind::NonMacroAttr { mark_used } => {
 683                     attr::mark_known(&attr);
 684                     if *mark_used {
 685                         attr::mark_used(&attr);
 686                     }
 687                     item.visit_attrs(|attrs| attrs.push(attr));
 688                     fragment_kind.expect_from_annotatables(iter::once(item))
 689                 }
 690                 _ => unreachable!(),
 691             },
 692             InvocationKind::Derive { path, item } => match ext {
 693                 SyntaxExtensionKind::Derive(expander)
 694                 | SyntaxExtensionKind::LegacyDerive(expander) => {
 695                     if !item.derive_allowed() {
 696                         return fragment_kind.dummy(span);
 697                     }
 698                     if let SyntaxExtensionKind::Derive(..) = ext {
 699                         self.gate_proc_macro_input(&item);
 700                     }
 701                     let meta = ast::MetaItem { kind: ast::MetaItemKind::Word, span, path };
 702                     let items = expander.expand(self.cx, span, &meta, item);
 703                     fragment_kind.expect_from_annotatables(items)
 704                 }
 705                 _ => unreachable!(),
 706             },
 707             InvocationKind::DeriveContainer { .. } => unreachable!(),
 708         }
 709     }
 710
 711     fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
 712         let kind = match item {
 713             Annotatable::Item(_)
 714             | Annotatable::TraitItem(_)
 715             | Annotatable::ImplItem(_)
 716             | Annotatable::ForeignItem(_) => return,
 717             Annotatable::Stmt(_) => "statements",
 718             Annotatable::Expr(_) => "expressions",
 719             Annotatable::Arm(..)
 720             | Annotatable::Field(..)
 721             | Annotatable::FieldPat(..)
 722             | Annotatable::GenericParam(..)
 723             | Annotatable::Param(..)
 724             | Annotatable::StructField(..)
 725             | Annotatable::Variant(..) => panic!("unexpected annotatable"),
 726         };
 727         if self.cx.ecfg.proc_macro_hygiene() {
 728             return;
 729         }
 730         feature_err(
 731             self.cx.parse_sess,
 732             sym::proc_macro_hygiene,
 733             span,
 734             &format!("custom attributes cannot be applied to {}", kind),
 735         )
 736         .emit();
 737     }
 738
 739     fn gate_proc_macro_input(&self, annotatable: &Annotatable) {
 740         struct GateProcMacroInput<'a> {
 741             parse_sess: &'a ParseSess,
 742         }
 743
 744         impl<'ast, 'a> Visitor<'ast> for GateProcMacroInput<'a> {
 745             fn visit_item(&mut self, item: &'ast ast::Item) {
 746                 match &item.kind {
 747                     ast::ItemKind::Mod(module) if !module.inline => {
 748                         feature_err(
 749                             self.parse_sess,
 750                             sym::proc_macro_hygiene,
 751                             item.span,
 752                             "non-inline modules in proc macro input are unstable",
 753                         )
 754                         .emit();
 755                     }
 756                     _ => {}
 757                 }
 758
 759                 visit::walk_item(self, item);
 760             }
 761
 762             fn visit_mac(&mut self, _: &'ast ast::Mac) {}
 763         }
 764
 765         if !self.cx.ecfg.proc_macro_hygiene() {
 766             annotatable.visit_with(&mut GateProcMacroInput { parse_sess: self.cx.parse_sess });
 767         }
 768     }
 769
 770     fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
 771         let kind = match kind {
 772             AstFragmentKind::Expr | AstFragmentKind::OptExpr => "expressions",
 773             AstFragmentKind::Pat => "patterns",
 774             AstFragmentKind::Stmts => "statements",
 775             AstFragmentKind::Ty
 776             | AstFragmentKind::Items
 777             | AstFragmentKind::TraitItems
 778             | AstFragmentKind::ImplItems
 779             | AstFragmentKind::ForeignItems => return,
 780             AstFragmentKind::Arms
 781             | AstFragmentKind::Fields
 782             | AstFragmentKind::FieldPats
 783             | AstFragmentKind::GenericParams
 784             | AstFragmentKind::Params
 785             | AstFragmentKind::StructFields
 786             | AstFragmentKind::Variants => panic!("unexpected AST fragment kind"),
 787         };
 788         if self.cx.ecfg.proc_macro_hygiene() {
 789             return;
 790         }
 791         feature_err(
 792             self.cx.parse_sess,
 793             sym::proc_macro_hygiene,
 794             span,
 795             &format!("procedural macros cannot be expanded to {}", kind),
 796         )
 797         .emit();
 798     }
 799
 800     fn parse_ast_fragment(
 801         &mut self,
 802         toks: TokenStream,
 803         kind: AstFragmentKind,
 804         path: &Path,
 805         span: Span,
 806     ) -> AstFragment {
 807         let mut parser = self.cx.new_parser_from_tts(toks);
 808         match parse_ast_fragment(&mut parser, kind, false) {
 809             Ok(fragment) => {
 810                 ensure_complete_parse(&mut parser, path, kind.name(), span);
 811                 fragment
 812             }
 813             Err(mut err) => {
 814                 err.set_span(span);
 815                 annotate_err_with_kind(&mut err, kind, span);
 816                 err.emit();
 817                 self.cx.trace_macros_diag();
 818                 kind.dummy(span)
 819             }
 820         }
 821     }
 822 }
 823
 824 pub fn parse_ast_fragment<'a>(
 825     this: &mut Parser<'a>,
 826     kind: AstFragmentKind,
 827     macro_legacy_warnings: bool,
 828 ) -> PResult<'a, AstFragment> {
 829     Ok(match kind {
 830         AstFragmentKind::Items => {
 831             let mut items = SmallVec::new();
 832             while let Some(item) = this.parse_item()? {
 833                 items.push(item);
 834             }
 835             AstFragment::Items(items)
 836         }
 837         AstFragmentKind::TraitItems => {
 838             let mut items = SmallVec::new();
 839             while this.token != token::Eof {
 840                 items.push(this.parse_trait_item(&mut false)?);
 841             }
 842             AstFragment::TraitItems(items)
 843         }
 844         AstFragmentKind::ImplItems => {
 845             let mut items = SmallVec::new();
 846             while this.token != token::Eof {
 847                 items.push(this.parse_impl_item(&mut false)?);
 848             }
 849             AstFragment::ImplItems(items)
 850         }
 851         AstFragmentKind::ForeignItems => {
 852             let mut items = SmallVec::new();
 853             while this.token != token::Eof {
 854                 items.push(this.parse_foreign_item(DUMMY_SP)?);
 855             }
 856             AstFragment::ForeignItems(items)
 857         }
 858         AstFragmentKind::Stmts => {
 859             let mut stmts = SmallVec::new();
 860             while this.token != token::Eof &&
 861                     // won't make progress on a `}`
 862                     this.token != token::CloseDelim(token::Brace)
 863             {
 864                 if let Some(stmt) = this.parse_full_stmt(macro_legacy_warnings)? {
 865                     stmts.push(stmt);
 866                 }
 867             }
 868             AstFragment::Stmts(stmts)
 869         }
 870         AstFragmentKind::Expr => AstFragment::Expr(this.parse_expr()?),
 871         AstFragmentKind::OptExpr => {
 872             if this.token != token::Eof {
 873                 AstFragment::OptExpr(Some(this.parse_expr()?))
 874             } else {
 875                 AstFragment::OptExpr(None)
 876             }
 877         }
 878         AstFragmentKind::Ty => AstFragment::Ty(this.parse_ty()?),
 879         AstFragmentKind::Pat => AstFragment::Pat(this.parse_pat(None)?),
 880         AstFragmentKind::Arms
 881         | AstFragmentKind::Fields
 882         | AstFragmentKind::FieldPats
 883         | AstFragmentKind::GenericParams
 884         | AstFragmentKind::Params
 885         | AstFragmentKind::StructFields
 886         | AstFragmentKind::Variants => panic!("unexpected AST fragment kind"),
 887     })
 888 }
 889
 890 pub fn ensure_complete_parse<'a>(
 891     this: &mut Parser<'a>,
 892     macro_path: &Path,
 893     kind_name: &str,
 894     span: Span,
 895 ) {
 896     if this.token != token::Eof {
 897         let token = pprust::token_to_string(&this.token);
 898         let msg = format!("macro expansion ignores token `{}` and any following", token);
 899         // Avoid emitting backtrace info twice.
 900         let def_site_span = this.token.span.with_ctxt(SyntaxContext::root());
 901         let mut err = this.struct_span_err(def_site_span, &msg);
 902         err.span_label(span, "caused by the macro expansion here");
 903         let msg = format!(
 904             "the usage of `{}!` is likely invalid in {} context",
 905             pprust::path_to_string(macro_path),
 906             kind_name,
 907         );
 908         err.note(&msg);
 909         let semi_span = this.sess.source_map().next_point(span);
 910
 911         let semi_full_span = semi_span.to(this.sess.source_map().next_point(semi_span));
 912         match this.sess.source_map().span_to_snippet(semi_full_span) {
 913             Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
 914                 err.span_suggestion(
 915                     semi_span,
 916                     "you might be missing a semicolon here",
 917                     ";".to_owned(),
 918                     Applicability::MaybeIncorrect,
 919                 );
 920             }
 921             _ => {}
 922         }
 923         err.emit();
 924     }
 925 }
 926
 927 struct InvocationCollector<'a, 'b> {
 928     cx: &'a mut ExtCtxt<'b>,
 929     cfg: StripUnconfigured<'a>,
 930     invocations: Vec<Invocation>,
 931     monotonic: bool,
 932 }
 933
 934 impl<'a, 'b> InvocationCollector<'a, 'b> {
 935     fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
 936         // Expansion data for all the collected invocations is set upon their resolution,
 937         // with exception of the derive container case which is not resolved and can get
 938         // its expansion data immediately.
 939         let expn_data = match &kind {
 940             InvocationKind::DeriveContainer { item, .. } => Some(ExpnData {
 941                 parent: self.cx.current_expansion.id,
 942                 ..ExpnData::default(
 943                     ExpnKind::Macro(MacroKind::Attr, sym::derive),
 944                     item.span(),
 945                     self.cx.parse_sess.edition,
 946                 )
 947             }),
 948             _ => None,
 949         };
 950         let expn_id = ExpnId::fresh(expn_data);
 951         let vis = kind.placeholder_visibility();
 952         self.invocations.push(Invocation {
 953             kind,
 954             fragment_kind,
 955             expansion_data: ExpansionData {
 956                 id: expn_id,
 957                 depth: self.cx.current_expansion.depth + 1,
 958                 ..self.cx.current_expansion.clone()
 959             },
 960         });
 961         placeholder(fragment_kind, NodeId::placeholder_from_expn_id(expn_id), vis)
 962     }
 963
 964     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
 965         self.collect(kind, InvocationKind::Bang { mac, span })
 966     }
 967
 968     fn collect_attr(
 969         &mut self,
 970         attr: Option<ast::Attribute>,
 971         derives: Vec<Path>,
 972         item: Annotatable,
 973         kind: AstFragmentKind,
 974         after_derive: bool,
 975     ) -> AstFragment {
 976         self.collect(
 977             kind,
 978             match attr {
 979                 Some(attr) => InvocationKind::Attr { attr, item, derives, after_derive },
 980                 None => InvocationKind::DeriveContainer { derives, item },
 981             },
 982         )
 983     }
 984
 985     fn find_attr_invoc(
 986         &self,
 987         attrs: &mut Vec<ast::Attribute>,
 988         after_derive: &mut bool,
 989     ) -> Option<ast::Attribute> {
 990         let attr = attrs
 991             .iter()
 992             .position(|a| {
 993                 if a.has_name(sym::derive) {
 994                     *after_derive = true;
 995                 }
 996                 !attr::is_known(a) && !is_builtin_attr(a)
 997             })
 998             .map(|i| attrs.remove(i));
 999         if let Some(attr) = &attr {
1000             if !self.cx.ecfg.custom_inner_attributes()
1001                 && attr.style == ast::AttrStyle::Inner
1002                 && !attr.has_name(sym::test)
1003             {
1004                 feature_err(
1005                     &self.cx.parse_sess,
1006                     sym::custom_inner_attributes,
1007                     attr.span,
1008                     "non-builtin inner attributes are unstable",
1009                 )
1010                 .emit();
1011             }
1012         }
1013         attr
1014     }
1015
1016     /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
1017     fn classify_item<T>(
1018         &mut self,
1019         item: &mut T,
1020     ) -> (Option<ast::Attribute>, Vec<Path>, /* after_derive */ bool)
1021     where
1022         T: HasAttrs,
1023     {
1024         let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
1025
1026         item.visit_attrs(|mut attrs| {
1027             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1028             traits = collect_derives(&mut self.cx, &mut attrs);
1029         });
1030
1031         (attr, traits, after_derive)
1032     }
1033
1034     /// Alternative to `classify_item()` that ignores `#[derive]` so invocations fallthrough
1035     /// to the unused-attributes lint (making it an error on statements and expressions
1036     /// is a breaking change)
1037     fn classify_nonitem<T: HasAttrs>(
1038         &mut self,
1039         nonitem: &mut T,
1040     ) -> (Option<ast::Attribute>, /* after_derive */ bool) {
1041         let (mut attr, mut after_derive) = (None, false);
1042
1043         nonitem.visit_attrs(|mut attrs| {
1044             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1045         });
1046
1047         (attr, after_derive)
1048     }
1049
1050     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
1051         self.cfg.configure(node)
1052     }
1053
1054     // Detect use of feature-gated or invalid attributes on macro invocations
1055     // since they will not be detected after macro expansion.
1056     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
1057         let features = self.cx.ecfg.features.unwrap();
1058         for attr in attrs.iter() {
1059             rustc_ast_passes::feature_gate::check_attribute(attr, self.cx.parse_sess, features);
1060             validate_attr::check_meta(self.cx.parse_sess, attr);
1061
1062             // macros are expanded before any lint passes so this warning has to be hardcoded
1063             if attr.has_name(sym::derive) {
1064                 self.cx
1065                     .struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
1066                     .note("this may become a hard error in a future release")
1067                     .emit();
1068             }
1069         }
1070     }
1071 }
1072
1073 impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
1074     fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
1075         self.cfg.configure_expr(expr);
1076         visit_clobber(expr.deref_mut(), |mut expr| {
1077             self.cfg.configure_expr_kind(&mut expr.kind);
1078
1079             // ignore derives so they remain unused
1080             let (attr, after_derive) = self.classify_nonitem(&mut expr);
1081
1082             if attr.is_some() {
1083                 // Collect the invoc regardless of whether or not attributes are permitted here
1084                 // expansion will eat the attribute so it won't error later.
1085                 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1086
1087                 // AstFragmentKind::Expr requires the macro to emit an expression.
1088                 return self
1089                     .collect_attr(
1090                         attr,
1091                         vec![],
1092                         Annotatable::Expr(P(expr)),
1093                         AstFragmentKind::Expr,
1094                         after_derive,
1095                     )
1096                     .make_expr()
1097                     .into_inner();
1098             }
1099
1100             if let ast::ExprKind::Mac(mac) = expr.kind {
1101                 self.check_attributes(&expr.attrs);
1102                 self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr().into_inner()
1103             } else {
1104                 noop_visit_expr(&mut expr, self);
1105                 expr
1106             }
1107         });
1108     }
1109
1110     fn flat_map_arm(&mut self, arm: ast::Arm) -> SmallVec<[ast::Arm; 1]> {
1111         let mut arm = configure!(self, arm);
1112
1113         let (attr, traits, after_derive) = self.classify_item(&mut arm);
1114         if attr.is_some() || !traits.is_empty() {
1115             return self
1116                 .collect_attr(
1117                     attr,
1118                     traits,
1119                     Annotatable::Arm(arm),
1120                     AstFragmentKind::Arms,
1121                     after_derive,
1122                 )
1123                 .make_arms();
1124         }
1125
1126         noop_flat_map_arm(arm, self)
1127     }
1128
1129     fn flat_map_field(&mut self, field: ast::Field) -> SmallVec<[ast::Field; 1]> {
1130         let mut field = configure!(self, field);
1131
1132         let (attr, traits, after_derive) = self.classify_item(&mut field);
1133         if attr.is_some() || !traits.is_empty() {
1134             return self
1135                 .collect_attr(
1136                     attr,
1137                     traits,
1138                     Annotatable::Field(field),
1139                     AstFragmentKind::Fields,
1140                     after_derive,
1141                 )
1142                 .make_fields();
1143         }
1144
1145         noop_flat_map_field(field, self)
1146     }
1147
1148     fn flat_map_field_pattern(&mut self, fp: ast::FieldPat) -> SmallVec<[ast::FieldPat; 1]> {
1149         let mut fp = configure!(self, fp);
1150
1151         let (attr, traits, after_derive) = self.classify_item(&mut fp);
1152         if attr.is_some() || !traits.is_empty() {
1153             return self
1154                 .collect_attr(
1155                     attr,
1156                     traits,
1157                     Annotatable::FieldPat(fp),
1158                     AstFragmentKind::FieldPats,
1159                     after_derive,
1160                 )
1161                 .make_field_patterns();
1162         }
1163
1164         noop_flat_map_field_pattern(fp, self)
1165     }
1166
1167     fn flat_map_param(&mut self, p: ast::Param) -> SmallVec<[ast::Param; 1]> {
1168         let mut p = configure!(self, p);
1169
1170         let (attr, traits, after_derive) = self.classify_item(&mut p);
1171         if attr.is_some() || !traits.is_empty() {
1172             return self
1173                 .collect_attr(
1174                     attr,
1175                     traits,
1176                     Annotatable::Param(p),
1177                     AstFragmentKind::Params,
1178                     after_derive,
1179                 )
1180                 .make_params();
1181         }
1182
1183         noop_flat_map_param(p, self)
1184     }
1185
1186     fn flat_map_struct_field(&mut self, sf: ast::StructField) -> SmallVec<[ast::StructField; 1]> {
1187         let mut sf = configure!(self, sf);
1188
1189         let (attr, traits, after_derive) = self.classify_item(&mut sf);
1190         if attr.is_some() || !traits.is_empty() {
1191             return self
1192                 .collect_attr(
1193                     attr,
1194                     traits,
1195                     Annotatable::StructField(sf),
1196                     AstFragmentKind::StructFields,
1197                     after_derive,
1198                 )
1199                 .make_struct_fields();
1200         }
1201
1202         noop_flat_map_struct_field(sf, self)
1203     }
1204
1205     fn flat_map_variant(&mut self, variant: ast::Variant) -> SmallVec<[ast::Variant; 1]> {
1206         let mut variant = configure!(self, variant);
1207
1208         let (attr, traits, after_derive) = self.classify_item(&mut variant);
1209         if attr.is_some() || !traits.is_empty() {
1210             return self
1211                 .collect_attr(
1212                     attr,
1213                     traits,
1214                     Annotatable::Variant(variant),
1215                     AstFragmentKind::Variants,
1216                     after_derive,
1217                 )
1218                 .make_variants();
1219         }
1220
1221         noop_flat_map_variant(variant, self)
1222     }
1223
1224     fn filter_map_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
1225         let expr = configure!(self, expr);
1226         expr.filter_map(|mut expr| {
1227             self.cfg.configure_expr_kind(&mut expr.kind);
1228
1229             // Ignore derives so they remain unused.
1230             let (attr, after_derive) = self.classify_nonitem(&mut expr);
1231
1232             if attr.is_some() {
1233                 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1234
1235                 return self
1236                     .collect_attr(
1237                         attr,
1238                         vec![],
1239                         Annotatable::Expr(P(expr)),
1240                         AstFragmentKind::OptExpr,
1241                         after_derive,
1242                     )
1243                     .make_opt_expr()
1244                     .map(|expr| expr.into_inner());
1245             }
1246
1247             if let ast::ExprKind::Mac(mac) = expr.kind {
1248                 self.check_attributes(&expr.attrs);
1249                 self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
1250                     .make_opt_expr()
1251                     .map(|expr| expr.into_inner())
1252             } else {
1253                 Some({
1254                     noop_visit_expr(&mut expr, self);
1255                     expr
1256                 })
1257             }
1258         })
1259     }
1260
1261     fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
1262         self.cfg.configure_pat(pat);
1263         match pat.kind {
1264             PatKind::Mac(_) => {}
1265             _ => return noop_visit_pat(pat, self),
1266         }
1267
1268         visit_clobber(pat, |mut pat| match mem::replace(&mut pat.kind, PatKind::Wild) {
1269             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
1270             _ => unreachable!(),
1271         });
1272     }
1273
1274     fn flat_map_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
1275         let mut stmt = configure!(self, stmt);
1276
1277         // we'll expand attributes on expressions separately
1278         if !stmt.is_expr() {
1279             let (attr, derives, after_derive) = if stmt.is_item() {
1280                 self.classify_item(&mut stmt)
1281             } else {
1282                 // ignore derives on non-item statements so it falls through
1283                 // to the unused-attributes lint
1284                 let (attr, after_derive) = self.classify_nonitem(&mut stmt);
1285                 (attr, vec![], after_derive)
1286             };
1287
1288             if attr.is_some() || !derives.is_empty() {
1289                 return self
1290                     .collect_attr(
1291                         attr,
1292                         derives,
1293                         Annotatable::Stmt(P(stmt)),
1294                         AstFragmentKind::Stmts,
1295                         after_derive,
1296                     )
1297                     .make_stmts();
1298             }
1299         }
1300
1301         if let StmtKind::Mac(mac) = stmt.kind {
1302             let (mac, style, attrs) = mac.into_inner();
1303             self.check_attributes(&attrs);
1304             let mut placeholder =
1305                 self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts).make_stmts();
1306
1307             // If this is a macro invocation with a semicolon, then apply that
1308             // semicolon to the final statement produced by expansion.
1309             if style == MacStmtStyle::Semicolon {
1310                 if let Some(stmt) = placeholder.pop() {
1311                     placeholder.push(stmt.add_trailing_semicolon());
1312                 }
1313             }
1314
1315             return placeholder;
1316         }
1317
1318         // The placeholder expander gives ids to statements, so we avoid folding the id here.
1319         let ast::Stmt { id, kind, span } = stmt;
1320         noop_flat_map_stmt_kind(kind, self)
1321             .into_iter()
1322             .map(|kind| ast::Stmt { id, kind, span })
1323             .collect()
1324     }
1325
1326     fn visit_block(&mut self, block: &mut P<Block>) {
1327         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
1328         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
1329         noop_visit_block(block, self);
1330         self.cx.current_expansion.directory_ownership = old_directory_ownership;
1331     }
1332
1333     fn flat_map_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
1334         let mut item = configure!(self, item);
1335
1336         let (attr, traits, after_derive) = self.classify_item(&mut item);
1337         if attr.is_some() || !traits.is_empty() {
1338             return self
1339                 .collect_attr(
1340                     attr,
1341                     traits,
1342                     Annotatable::Item(item),
1343                     AstFragmentKind::Items,
1344                     after_derive,
1345                 )
1346                 .make_items();
1347         }
1348
1349         match item.kind {
1350             ast::ItemKind::Mac(..) => {
1351                 self.check_attributes(&item.attrs);
1352                 item.and_then(|item| match item.kind {
1353                     ItemKind::Mac(mac) => self
1354                         .collect(
1355                             AstFragmentKind::Items,
1356                             InvocationKind::Bang { mac, span: item.span },
1357                         )
1358                         .make_items(),
1359                     _ => unreachable!(),
1360                 })
1361             }
1362             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
1363                 if item.ident == Ident::invalid() {
1364                     return noop_flat_map_item(item, self);
1365                 }
1366
1367                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
1368                 let mut module = (*self.cx.current_expansion.module).clone();
1369                 module.mod_path.push(item.ident);
1370
1371                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
1372                 // In the non-inline case, `inner` is never the dummy span (cf. `parse_item_mod`).
1373                 // Thus, if `inner` is the dummy span, we know the module is inline.
1374                 let inline_module = item.span.contains(inner) || inner.is_dummy();
1375
1376                 if inline_module {
1377                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, sym::path) {
1378                         self.cx.current_expansion.directory_ownership =
1379                             DirectoryOwnership::Owned { relative: None };
1380                         module.directory.push(&*path.as_str());
1381                     } else {
1382                         module.directory.push(&*item.ident.as_str());
1383                     }
1384                 } else {
1385                     let path = self.cx.parse_sess.source_map().span_to_unmapped_path(inner);
1386                     let mut path = match path {
1387                         FileName::Real(path) => path,
1388                         other => PathBuf::from(other.to_string()),
1389                     };
1390                     let directory_ownership = match path.file_name().unwrap().to_str() {
1391                         Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
1392                         Some(_) => DirectoryOwnership::Owned { relative: Some(item.ident) },
1393                         None => DirectoryOwnership::UnownedViaMod,
1394                     };
1395                     path.pop();
1396                     module.directory = path;
1397                     self.cx.current_expansion.directory_ownership = directory_ownership;
1398                 }
1399
1400                 let orig_module =
1401                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
1402                 let result = noop_flat_map_item(item, self);
1403                 self.cx.current_expansion.module = orig_module;
1404                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
1405                 result
1406             }
1407
1408             _ => noop_flat_map_item(item, self),
1409         }
1410     }
1411
1412     fn flat_map_trait_item(&mut self, item: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
1413         let mut item = configure!(self, item);
1414
1415         let (attr, traits, after_derive) = self.classify_item(&mut item);
1416         if attr.is_some() || !traits.is_empty() {
1417             return self
1418                 .collect_attr(
1419                     attr,
1420                     traits,
1421                     Annotatable::TraitItem(item),
1422                     AstFragmentKind::TraitItems,
1423                     after_derive,
1424                 )
1425                 .make_trait_items();
1426         }
1427
1428         match item.kind {
1429             ast::AssocItemKind::Macro(..) => {
1430                 self.check_attributes(&item.attrs);
1431                 item.and_then(|item| match item.kind {
1432                     ast::AssocItemKind::Macro(mac) => self
1433                         .collect_bang(mac, item.span, AstFragmentKind::TraitItems)
1434                         .make_trait_items(),
1435                     _ => unreachable!(),
1436                 })
1437             }
1438             _ => noop_flat_map_assoc_item(item, self),
1439         }
1440     }
1441
1442     fn flat_map_impl_item(&mut self, item: P<ast::AssocItem>) -> SmallVec<[P<ast::AssocItem>; 1]> {
1443         let mut item = configure!(self, item);
1444
1445         let (attr, traits, after_derive) = self.classify_item(&mut item);
1446         if attr.is_some() || !traits.is_empty() {
1447             return self
1448                 .collect_attr(
1449                     attr,
1450                     traits,
1451                     Annotatable::ImplItem(item),
1452                     AstFragmentKind::ImplItems,
1453                     after_derive,
1454                 )
1455                 .make_impl_items();
1456         }
1457
1458         match item.kind {
1459             ast::AssocItemKind::Macro(..) => {
1460                 self.check_attributes(&item.attrs);
1461                 item.and_then(|item| match item.kind {
1462                     ast::AssocItemKind::Macro(mac) => self
1463                         .collect_bang(mac, item.span, AstFragmentKind::ImplItems)
1464                         .make_impl_items(),
1465                     _ => unreachable!(),
1466                 })
1467             }
1468             _ => noop_flat_map_assoc_item(item, self),
1469         }
1470     }
1471
1472     fn visit_ty(&mut self, ty: &mut P<ast::Ty>) {
1473         match ty.kind {
1474             ast::TyKind::Mac(_) => {}
1475             _ => return noop_visit_ty(ty, self),
1476         };
1477
1478         visit_clobber(ty, |mut ty| match mem::replace(&mut ty.kind, ast::TyKind::Err) {
1479             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
1480             _ => unreachable!(),
1481         });
1482     }
1483
1484     fn visit_foreign_mod(&mut self, foreign_mod: &mut ast::ForeignMod) {
1485         self.cfg.configure_foreign_mod(foreign_mod);
1486         noop_visit_foreign_mod(foreign_mod, self);
1487     }
1488
1489     fn flat_map_foreign_item(
1490         &mut self,
1491         mut foreign_item: P<ast::ForeignItem>,
1492     ) -> SmallVec<[P<ast::ForeignItem>; 1]> {
1493         let (attr, traits, after_derive) = self.classify_item(&mut foreign_item);
1494
1495         if attr.is_some() || !traits.is_empty() {
1496             return self
1497                 .collect_attr(
1498                     attr,
1499                     traits,
1500                     Annotatable::ForeignItem(foreign_item),
1501                     AstFragmentKind::ForeignItems,
1502                     after_derive,
1503                 )
1504                 .make_foreign_items();
1505         }
1506
1507         match foreign_item.kind {
1508             ast::ForeignItemKind::Macro(..) => {
1509                 self.check_attributes(&foreign_item.attrs);
1510                 foreign_item.and_then(|item| match item.kind {
1511                     ast::ForeignItemKind::Macro(mac) => self
1512                         .collect_bang(mac, item.span, AstFragmentKind::ForeignItems)
1513                         .make_foreign_items(),
1514                     _ => unreachable!(),
1515                 })
1516             }
1517             _ => noop_flat_map_foreign_item(foreign_item, self),
1518         }
1519     }
1520
1521     fn visit_item_kind(&mut self, item: &mut ast::ItemKind) {
1522         match item {
1523             ast::ItemKind::MacroDef(..) => {}
1524             _ => {
1525                 self.cfg.configure_item_kind(item);
1526                 noop_visit_item_kind(item, self);
1527             }
1528         }
1529     }
1530
1531     fn flat_map_generic_param(
1532         &mut self,
1533         param: ast::GenericParam,
1534     ) -> SmallVec<[ast::GenericParam; 1]> {
1535         let mut param = configure!(self, param);
1536
1537         let (attr, traits, after_derive) = self.classify_item(&mut param);
1538         if attr.is_some() || !traits.is_empty() {
1539             return self
1540                 .collect_attr(
1541                     attr,
1542                     traits,
1543                     Annotatable::GenericParam(param),
1544                     AstFragmentKind::GenericParams,
1545                     after_derive,
1546                 )
1547                 .make_generic_params();
1548         }
1549
1550         noop_flat_map_generic_param(param, self)
1551     }
1552
1553     fn visit_attribute(&mut self, at: &mut ast::Attribute) {
1554         // turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
1555         // contents="file contents")]` attributes
1556         if !at.check_name(sym::doc) {
1557             return noop_visit_attribute(at, self);
1558         }
1559
1560         if let Some(list) = at.meta_item_list() {
1561             if !list.iter().any(|it| it.check_name(sym::include)) {
1562                 return noop_visit_attribute(at, self);
1563             }
1564
1565             let mut items = vec![];
1566
1567             for mut it in list {
1568                 if !it.check_name(sym::include) {
1569                     items.push({
1570                         noop_visit_meta_list_item(&mut it, self);
1571                         it
1572                     });
1573                     continue;
1574                 }
1575
1576                 if let Some(file) = it.value_str() {
1577                     let err_count = self.cx.parse_sess.span_diagnostic.err_count();
1578                     self.check_attributes(slice::from_ref(at));
1579                     if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
1580                         // avoid loading the file if they haven't enabled the feature
1581                         return noop_visit_attribute(at, self);
1582                     }
1583
1584                     let filename = match self.cx.resolve_path(&*file.as_str(), it.span()) {
1585                         Ok(filename) => filename,
1586                         Err(mut err) => {
1587                             err.emit();
1588                             continue;
1589                         }
1590                     };
1591
1592                     match self.cx.source_map().load_file(&filename) {
1593                         Ok(source_file) => {
1594                             let src = source_file
1595                                 .src
1596                                 .as_ref()
1597                                 .expect("freshly loaded file should have a source");
1598                             let src_interned = Symbol::intern(src.as_str());
1599
1600                             let include_info = vec![
1601                                 ast::NestedMetaItem::MetaItem(attr::mk_name_value_item_str(
1602                                     Ident::with_dummy_span(sym::file),
1603                                     file,
1604                                     DUMMY_SP,
1605                                 )),
1606                                 ast::NestedMetaItem::MetaItem(attr::mk_name_value_item_str(
1607                                     Ident::with_dummy_span(sym::contents),
1608                                     src_interned,
1609                                     DUMMY_SP,
1610                                 )),
1611                             ];
1612
1613                             let include_ident = Ident::with_dummy_span(sym::include);
1614                             let item = attr::mk_list_item(include_ident, include_info);
1615                             items.push(ast::NestedMetaItem::MetaItem(item));
1616                         }
1617                         Err(e) => {
1618                             let lit =
1619                                 it.meta_item().and_then(|item| item.name_value_literal()).unwrap();
1620
1621                             if e.kind() == ErrorKind::InvalidData {
1622                                 self.cx
1623                                     .struct_span_err(
1624                                         lit.span,
1625                                         &format!("{} wasn't a utf-8 file", filename.display()),
1626                                     )
1627                                     .span_label(lit.span, "contains invalid utf-8")
1628                                     .emit();
1629                             } else {
1630                                 let mut err = self.cx.struct_span_err(
1631                                     lit.span,
1632                                     &format!("couldn't read {}: {}", filename.display(), e),
1633                                 );
1634                                 err.span_label(lit.span, "couldn't read file");
1635
1636                                 err.emit();
1637                             }
1638                         }
1639                     }
1640                 } else {
1641                     let mut err = self.cx.struct_span_err(
1642                         it.span(),
1643                         &format!("expected path to external documentation"),
1644                     );
1645
1646                     // Check if the user erroneously used `doc(include(...))` syntax.
1647                     let literal = it.meta_item_list().and_then(|list| {
1648                         if list.len() == 1 {
1649                             list[0].literal().map(|literal| &literal.kind)
1650                         } else {
1651                             None
1652                         }
1653                     });
1654
1655                     let (path, applicability) = match &literal {
1656                         Some(LitKind::Str(path, ..)) => {
1657                             (path.to_string(), Applicability::MachineApplicable)
1658                         }
1659                         _ => (String::from("<path>"), Applicability::HasPlaceholders),
1660                     };
1661
1662                     err.span_suggestion(
1663                         it.span(),
1664                         "provide a file path with `=`",
1665                         format!("include = \"{}\"", path),
1666                         applicability,
1667                     );
1668
1669                     err.emit();
1670                 }
1671             }
1672
1673             let meta = attr::mk_list_item(Ident::with_dummy_span(sym::doc), items);
1674             *at = ast::Attribute {
1675                 kind: ast::AttrKind::Normal(AttrItem {
1676                     path: meta.path,
1677                     args: meta.kind.mac_args(meta.span),
1678                 }),
1679                 span: at.span,
1680                 id: at.id,
1681                 style: at.style,
1682             };
1683         } else {
1684             noop_visit_attribute(at, self)
1685         }
1686     }
1687
1688     fn visit_id(&mut self, id: &mut ast::NodeId) {
1689         if self.monotonic {
1690             debug_assert_eq!(*id, ast::DUMMY_NODE_ID);
1691             *id = self.cx.resolver.next_node_id()
1692         }
1693     }
1694
1695     fn visit_fn_decl(&mut self, mut fn_decl: &mut P<ast::FnDecl>) {
1696         self.cfg.configure_fn_decl(&mut fn_decl);
1697         noop_visit_fn_decl(fn_decl, self);
1698     }
1699 }
1700
1701 pub struct ExpansionConfig<'feat> {
1702     pub crate_name: String,
1703     pub features: Option<&'feat Features>,
1704     pub recursion_limit: usize,
1705     pub trace_mac: bool,
1706     pub should_test: bool, // If false, strip `#[test]` nodes
1707     pub single_step: bool,
1708     pub keep_macs: bool,
1709 }
1710
1711 impl<'feat> ExpansionConfig<'feat> {
1712     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1713         ExpansionConfig {
1714             crate_name,
1715             features: None,
1716             recursion_limit: 1024,
1717             trace_mac: false,
1718             should_test: false,
1719             single_step: false,
1720             keep_macs: false,
1721         }
1722     }
1723
1724     fn proc_macro_hygiene(&self) -> bool {
1725         self.features.map_or(false, |features| features.proc_macro_hygiene)
1726     }
1727     fn custom_inner_attributes(&self) -> bool {
1728         self.features.map_or(false, |features| features.custom_inner_attributes)
1729     }
1730 }