src/libsyntax/ext/expand.rs

   1 use ast::{self, Block, Ident, LitKind, NodeId, PatKind, Path};
   2 use ast::{MacStmtStyle, StmtKind, ItemKind};
   3 use attr::{self, HasAttrs};
   4 use source_map::{ExpnInfo, MacroBang, MacroAttribute, dummy_spanned, respan};
   5 use config::StripUnconfigured;
   6 use errors::{Applicability, FatalError};
   7 use ext::base::*;
   8 use ext::derive::{add_derived_markers, collect_derives};
   9 use ext::hygiene::{self, Mark, SyntaxContext};
  10 use ext::placeholders::{placeholder, PlaceholderExpander};
  11 use feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
  12 use fold;
  13 use fold::*;
  14 use parse::{DirectoryOwnership, PResult, ParseSess};
  15 use parse::token::{self, Token};
  16 use parse::parser::Parser;
  17 use ptr::P;
  18 use smallvec::SmallVec;
  19 use symbol::Symbol;
  20 use symbol::keywords;
  21 use syntax_pos::{Span, DUMMY_SP, FileName};
  22 use syntax_pos::hygiene::ExpnFormat;
  23 use tokenstream::{TokenStream, TokenTree};
  24 use visit::{self, Visitor};
  25
  26 use rustc_data_structures::fx::FxHashMap;
  27 use std::fs;
  28 use std::io::ErrorKind;
  29 use std::{iter, mem};
  30 use std::rc::Rc;
  31 use std::path::PathBuf;
  32
  33 macro_rules! ast_fragments {
  34     (
  35         $($Kind:ident($AstTy:ty) {
  36             $kind_name:expr;
  37             // FIXME: HACK: this should be `$(one ...)?` and `$(many ...)?` but `?` macro
  38             // repetition was removed from 2015 edition in #51587 because of ambiguities.
  39             $(one fn $fold_ast:ident; fn $visit_ast:ident;)*
  40             $(many fn $fold_ast_elt:ident; fn $visit_ast_elt:ident;)*
  41             fn $make_ast:ident;
  42         })*
  43     ) => {
  44         /// A fragment of AST that can be produced by a single macro expansion.
  45         /// Can also serve as an input and intermediate result for macro expansion operations.
  46         pub enum AstFragment {
  47             OptExpr(Option<P<ast::Expr>>),
  48             $($Kind($AstTy),)*
  49         }
  50
  51         /// "Discriminant" of an AST fragment.
  52         #[derive(Copy, Clone, PartialEq, Eq)]
  53         pub enum AstFragmentKind {
  54             OptExpr,
  55             $($Kind,)*
  56         }
  57
  58         impl AstFragmentKind {
  59             pub fn name(self) -> &'static str {
  60                 match self {
  61                     AstFragmentKind::OptExpr => "expression",
  62                     $(AstFragmentKind::$Kind => $kind_name,)*
  63                 }
  64             }
  65
  66             fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
  67                 match self {
  68                     AstFragmentKind::OptExpr =>
  69                         result.make_expr().map(Some).map(AstFragment::OptExpr),
  70                     $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
  71                 }
  72             }
  73         }
  74
  75         impl AstFragment {
  76             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  77                 match self {
  78                     AstFragment::OptExpr(expr) => expr,
  79                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
  80                 }
  81             }
  82
  83             $(pub fn $make_ast(self) -> $AstTy {
  84                 match self {
  85                     AstFragment::$Kind(ast) => ast,
  86                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
  87                 }
  88             })*
  89
  90             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
  91                 match self {
  92                     AstFragment::OptExpr(expr) =>
  93                         AstFragment::OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
  94                     $($(AstFragment::$Kind(ast) =>
  95                         AstFragment::$Kind(folder.$fold_ast(ast)),)*)*
  96                     $($(AstFragment::$Kind(ast) =>
  97                         AstFragment::$Kind(ast.into_iter()
  98                                               .flat_map(|ast| folder.$fold_ast_elt(ast))
  99                                               .collect()),)*)*
 100                 }
 101             }
 102
 103             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
 104                 match *self {
 105                     AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
 106                     AstFragment::OptExpr(None) => {}
 107                     $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)*)*
 108                     $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
 109                         visitor.$visit_ast_elt(ast_elt);
 110                     })*)*
 111                 }
 112             }
 113         }
 114
 115         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 116             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 117                 self.expand_fragment(AstFragment::OptExpr(Some(expr))).make_opt_expr()
 118             }
 119             $($(fn $fold_ast(&mut self, ast: $AstTy) -> $AstTy {
 120                 self.expand_fragment(AstFragment::$Kind(ast)).$make_ast()
 121             })*)*
 122             $($(fn $fold_ast_elt(&mut self, ast_elt: <$AstTy as IntoIterator>::Item) -> $AstTy {
 123                 self.expand_fragment(AstFragment::$Kind(smallvec![ast_elt])).$make_ast()
 124             })*)*
 125         }
 126
 127         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 128             $(fn $make_ast(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>)
 129                            -> Option<$AstTy> {
 130                 Some(self.make(AstFragmentKind::$Kind).$make_ast())
 131             })*
 132         }
 133     }
 134 }
 135
 136 ast_fragments! {
 137     Expr(P<ast::Expr>) { "expression"; one fn fold_expr; fn visit_expr; fn make_expr; }
 138     Pat(P<ast::Pat>) { "pattern"; one fn fold_pat; fn visit_pat; fn make_pat; }
 139     Ty(P<ast::Ty>) { "type"; one fn fold_ty; fn visit_ty; fn make_ty; }
 140     Stmts(SmallVec<[ast::Stmt; 1]>) {
 141         "statement"; many fn fold_stmt; fn visit_stmt; fn make_stmts;
 142     }
 143     Items(SmallVec<[P<ast::Item>; 1]>) {
 144         "item"; many fn fold_item; fn visit_item; fn make_items;
 145     }
 146     TraitItems(SmallVec<[ast::TraitItem; 1]>) {
 147         "trait item"; many fn fold_trait_item; fn visit_trait_item; fn make_trait_items;
 148     }
 149     ImplItems(SmallVec<[ast::ImplItem; 1]>) {
 150         "impl item"; many fn fold_impl_item; fn visit_impl_item; fn make_impl_items;
 151     }
 152     ForeignItems(SmallVec<[ast::ForeignItem; 1]>) {
 153         "foreign item"; many fn fold_foreign_item; fn visit_foreign_item; fn make_foreign_items;
 154     }
 155 }
 156
 157 impl AstFragmentKind {
 158     fn dummy(self, span: Span) -> Option<AstFragment> {
 159         self.make_from(DummyResult::any(span))
 160     }
 161
 162     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
 163                                                                      -> AstFragment {
 164         let mut items = items.into_iter();
 165         match self {
 166             AstFragmentKind::Items =>
 167                 AstFragment::Items(items.map(Annotatable::expect_item).collect()),
 168             AstFragmentKind::ImplItems =>
 169                 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 170             AstFragmentKind::TraitItems =>
 171                 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 172             AstFragmentKind::ForeignItems =>
 173                 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect()),
 174             AstFragmentKind::Stmts =>
 175                 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect()),
 176             AstFragmentKind::Expr => AstFragment::Expr(
 177                 items.next().expect("expected exactly one expression").expect_expr()
 178             ),
 179             AstFragmentKind::OptExpr =>
 180                 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr)),
 181             AstFragmentKind::Pat | AstFragmentKind::Ty =>
 182                 panic!("patterns and types aren't annotatable"),
 183         }
 184     }
 185 }
 186
 187 fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
 188     // We don't want to format a path using pretty-printing,
 189     // `format!("{}", path)`, because that tries to insert
 190     // line-breaks and is slow.
 191     let mut path_str = String::with_capacity(64);
 192     for (i, segment) in path.segments.iter().enumerate() {
 193         if i != 0 {
 194             path_str.push_str("::");
 195         }
 196         if segment.ident.name != keywords::PathRoot.name() {
 197             path_str.push_str(&segment.ident.as_str())
 198         }
 199     }
 200
 201     MacroBang(Symbol::intern(&path_str))
 202 }
 203
 204 pub struct Invocation {
 205     pub kind: InvocationKind,
 206     fragment_kind: AstFragmentKind,
 207     pub expansion_data: ExpansionData,
 208 }
 209
 210 pub enum InvocationKind {
 211     Bang {
 212         mac: ast::Mac,
 213         ident: Option<Ident>,
 214         span: Span,
 215     },
 216     Attr {
 217         attr: Option<ast::Attribute>,
 218         traits: Vec<Path>,
 219         item: Annotatable,
 220         // We temporarily report errors for attribute macros placed after derives
 221         after_derive: bool,
 222     },
 223     Derive {
 224         path: Path,
 225         item: Annotatable,
 226     },
 227 }
 228
 229 impl Invocation {
 230     pub fn span(&self) -> Span {
 231         match self.kind {
 232             InvocationKind::Bang { span, .. } => span,
 233             InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
 234             InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
 235             InvocationKind::Derive { ref path, .. } => path.span,
 236         }
 237     }
 238 }
 239
 240 pub struct MacroExpander<'a, 'b:'a> {
 241     pub cx: &'a mut ExtCtxt<'b>,
 242     monotonic: bool, // cf. `cx.monotonic_expander()`
 243 }
 244
 245 impl<'a, 'b> MacroExpander<'a, 'b> {
 246     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 247         MacroExpander { cx: cx, monotonic: monotonic }
 248     }
 249
 250     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 251         let mut module = ModuleData {
 252             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 253             directory: match self.cx.source_map().span_to_unmapped_path(krate.span) {
 254                 FileName::Real(path) => path,
 255                 other => PathBuf::from(other.to_string()),
 256             },
 257         };
 258         module.directory.pop();
 259         self.cx.root_path = module.directory.clone();
 260         self.cx.current_expansion.module = Rc::new(module);
 261         self.cx.current_expansion.crate_span = Some(krate.span);
 262
 263         let orig_mod_span = krate.module.inner;
 264
 265         let krate_item = AstFragment::Items(smallvec![P(ast::Item {
 266             attrs: krate.attrs,
 267             span: krate.span,
 268             node: ast::ItemKind::Mod(krate.module),
 269             ident: keywords::Invalid.ident(),
 270             id: ast::DUMMY_NODE_ID,
 271             vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
 272             tokens: None,
 273         })]);
 274
 275         match self.expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
 276             Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
 277                 krate.attrs = attrs;
 278                 krate.module = module;
 279             },
 280             None => {
 281                 // Resolution failed so we return an empty expansion
 282                 krate.attrs = vec![];
 283                 krate.module = ast::Mod {
 284                     inner: orig_mod_span,
 285                     items: vec![],
 286                     inline: true,
 287                 };
 288             },
 289             _ => unreachable!(),
 290         };
 291         self.cx.trace_macros_diag();
 292         krate
 293     }
 294
 295     // Fully expand all macro invocations in this AST fragment.
 296     fn expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
 297         let orig_expansion_data = self.cx.current_expansion.clone();
 298         self.cx.current_expansion.depth = 0;
 299
 300         // Collect all macro invocations and replace them with placeholders.
 301         let (fragment_with_placeholders, mut invocations)
 302             = self.collect_invocations(input_fragment, &[]);
 303
 304         // Optimization: if we resolve all imports now,
 305         // we'll be able to immediately resolve most of imported macros.
 306         self.resolve_imports();
 307
 308         // Resolve paths in all invocations and produce output expanded fragments for them, but
 309         // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
 310         // The output fragments also go through expansion recursively until no invocations are left.
 311         // Unresolved macros produce dummy outputs as a recovery measure.
 312         invocations.reverse();
 313         let mut expanded_fragments = Vec::new();
 314         let mut derives: FxHashMap<Mark, Vec<_>> = FxHashMap::default();
 315         let mut undetermined_invocations = Vec::new();
 316         let (mut progress, mut force) = (false, !self.monotonic);
 317         loop {
 318             let invoc = if let Some(invoc) = invocations.pop() {
 319                 invoc
 320             } else {
 321                 self.resolve_imports();
 322                 if undetermined_invocations.is_empty() { break }
 323                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 324                 force = !mem::replace(&mut progress, false);
 325                 continue
 326             };
 327
 328             let scope =
 329                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 330             let ext = match self.cx.resolver.resolve_macro_invocation(&invoc, scope, force) {
 331                 Ok(ext) => Some(ext),
 332                 Err(Determinacy::Determined) => None,
 333                 Err(Determinacy::Undetermined) => {
 334                     undetermined_invocations.push(invoc);
 335                     continue
 336                 }
 337             };
 338
 339             progress = true;
 340             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
 341             self.cx.current_expansion = invoc.expansion_data.clone();
 342
 343             self.cx.current_expansion.mark = scope;
 344             // FIXME(jseyfried): Refactor out the following logic
 345             let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
 346                 if let Some(ext) = ext {
 347                     let (invoc_fragment_kind, invoc_span) = (invoc.fragment_kind, invoc.span());
 348                     let fragment = self.expand_invoc(invoc, &*ext).unwrap_or_else(|| {
 349                         invoc_fragment_kind.dummy(invoc_span).unwrap()
 350                     });
 351                     self.collect_invocations(fragment, &[])
 352                 } else if let InvocationKind::Attr { attr: None, traits, item, .. } = invoc.kind {
 353                     if !item.derive_allowed() {
 354                         let attr = attr::find_by_name(item.attrs(), "derive")
 355                             .expect("`derive` attribute should exist");
 356                         let span = attr.span;
 357                         let mut err = self.cx.mut_span_err(span,
 358                                                            "`derive` may only be applied to \
 359                                                             structs, enums and unions");
 360                         if let ast::AttrStyle::Inner = attr.style {
 361                             let trait_list = traits.iter()
 362                                 .map(|t| t.to_string()).collect::<Vec<_>>();
 363                             let suggestion = format!("#[derive({})]", trait_list.join(", "));
 364                             err.span_suggestion_with_applicability(
 365                                 span, "try an outer attribute", suggestion,
 366                                 // We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
 367                                 Applicability::MaybeIncorrect
 368                             );
 369                         }
 370                         err.emit();
 371                     }
 372
 373                     let item = self.fully_configure(item)
 374                         .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
 375                     let item_with_markers =
 376                         add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
 377                     let derives = derives.entry(invoc.expansion_data.mark).or_default();
 378
 379                     derives.reserve(traits.len());
 380                     invocations.reserve(traits.len());
 381                     for path in &traits {
 382                         let mark = Mark::fresh(self.cx.current_expansion.mark);
 383                         derives.push(mark);
 384                         let item = match self.cx.resolver.resolve_macro_path(
 385                                 path, MacroKind::Derive, Mark::root(), Vec::new(), false) {
 386                             Ok(ext) => match *ext {
 387                                 BuiltinDerive(..) => item_with_markers.clone(),
 388                                 _ => item.clone(),
 389                             },
 390                             _ => item.clone(),
 391                         };
 392                         invocations.push(Invocation {
 393                             kind: InvocationKind::Derive { path: path.clone(), item: item },
 394                             fragment_kind: invoc.fragment_kind,
 395                             expansion_data: ExpansionData {
 396                                 mark,
 397                                 ..invoc.expansion_data.clone()
 398                             },
 399                         });
 400                     }
 401                     let fragment = invoc.fragment_kind
 402                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 403                     self.collect_invocations(fragment, derives)
 404                 } else {
 405                     unreachable!()
 406                 }
 407             } else {
 408                 self.collect_invocations(invoc.fragment_kind.dummy(invoc.span()).unwrap(), &[])
 409             };
 410
 411             if expanded_fragments.len() < depth {
 412                 expanded_fragments.push(Vec::new());
 413             }
 414             expanded_fragments[depth - 1].push((mark, expanded_fragment));
 415             if !self.cx.ecfg.single_step {
 416                 invocations.extend(new_invocations.into_iter().rev());
 417             }
 418         }
 419
 420         self.cx.current_expansion = orig_expansion_data;
 421
 422         // Finally incorporate all the expanded macros into the input AST fragment.
 423         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 424         while let Some(expanded_fragments) = expanded_fragments.pop() {
 425             for (mark, expanded_fragment) in expanded_fragments.into_iter().rev() {
 426                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 427                 placeholder_expander.add(NodeId::placeholder_from_mark(mark),
 428                                          expanded_fragment, derives);
 429             }
 430         }
 431         fragment_with_placeholders.fold_with(&mut placeholder_expander)
 432     }
 433
 434     fn resolve_imports(&mut self) {
 435         if self.monotonic {
 436             self.cx.resolver.resolve_imports();
 437         }
 438     }
 439
 440     /// Collect all macro invocations reachable at this time in this AST fragment, and replace
 441     /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
 442     /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
 443     /// prepares data for resolving paths of macro invocations.
 444     fn collect_invocations(&mut self, fragment: AstFragment, derives: &[Mark])
 445                            -> (AstFragment, Vec<Invocation>) {
 446         let (fragment_with_placeholders, invocations) = {
 447             let mut collector = InvocationCollector {
 448                 cfg: StripUnconfigured {
 449                     sess: self.cx.parse_sess,
 450                     features: self.cx.ecfg.features,
 451                 },
 452                 cx: self.cx,
 453                 invocations: Vec::new(),
 454                 monotonic: self.monotonic,
 455             };
 456             (fragment.fold_with(&mut collector), collector.invocations)
 457         };
 458
 459         if self.monotonic {
 460             self.cx.resolver.visit_ast_fragment_with_placeholders(
 461                 self.cx.current_expansion.mark, &fragment_with_placeholders, derives
 462             );
 463         }
 464
 465         (fragment_with_placeholders, invocations)
 466     }
 467
 468     fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
 469         let mut cfg = StripUnconfigured {
 470             sess: self.cx.parse_sess,
 471             features: self.cx.ecfg.features,
 472         };
 473         // Since the item itself has already been configured by the InvocationCollector,
 474         // we know that fold result vector will contain exactly one element
 475         match item {
 476             Annotatable::Item(item) => {
 477                 Annotatable::Item(cfg.fold_item(item).pop().unwrap())
 478             }
 479             Annotatable::TraitItem(item) => {
 480                 Annotatable::TraitItem(item.map(|item| cfg.fold_trait_item(item).pop().unwrap()))
 481             }
 482             Annotatable::ImplItem(item) => {
 483                 Annotatable::ImplItem(item.map(|item| cfg.fold_impl_item(item).pop().unwrap()))
 484             }
 485             Annotatable::ForeignItem(item) => {
 486                 Annotatable::ForeignItem(
 487                     item.map(|item| cfg.fold_foreign_item(item).pop().unwrap())
 488                 )
 489             }
 490             Annotatable::Stmt(stmt) => {
 491                 Annotatable::Stmt(stmt.map(|stmt| cfg.fold_stmt(stmt).pop().unwrap()))
 492             }
 493             Annotatable::Expr(expr) => {
 494                 Annotatable::Expr(cfg.fold_expr(expr))
 495             }
 496         }
 497     }
 498
 499     fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
 500         if invoc.fragment_kind == AstFragmentKind::ForeignItems &&
 501            !self.cx.ecfg.macros_in_extern_enabled() {
 502             if let SyntaxExtension::NonMacroAttr { .. } = *ext {} else {
 503                 emit_feature_err(&self.cx.parse_sess, "macros_in_extern",
 504                                  invoc.span(), GateIssue::Language,
 505                                  "macro invocations in `extern {}` blocks are experimental");
 506             }
 507         }
 508
 509         let result = match invoc.kind {
 510             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext)?,
 511             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext)?,
 512             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext)?,
 513         };
 514
 515         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
 516             let info = self.cx.current_expansion.mark.expn_info().unwrap();
 517             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
 518             let mut err = self.cx.struct_span_err(info.call_site,
 519                 &format!("recursion limit reached while expanding the macro `{}`",
 520                          info.format.name()));
 521             err.help(&format!(
 522                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
 523                 suggested_limit));
 524             err.emit();
 525             self.cx.trace_macros_diag();
 526             FatalError.raise();
 527         }
 528
 529         Some(result)
 530     }
 531
 532     fn expand_attr_invoc(&mut self,
 533                          invoc: Invocation,
 534                          ext: &SyntaxExtension)
 535                          -> Option<AstFragment> {
 536         let (attr, item) = match invoc.kind {
 537             InvocationKind::Attr { attr, item, .. } => (attr?, item),
 538             _ => unreachable!(),
 539         };
 540
 541         if let NonMacroAttr { mark_used: false } = *ext {} else {
 542             // Macro attrs are always used when expanded,
 543             // non-macro attrs are considered used when the field says so.
 544             attr::mark_used(&attr);
 545         }
 546         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 547             call_site: attr.span,
 548             def_site: None,
 549             format: MacroAttribute(Symbol::intern(&attr.path.to_string())),
 550             allow_internal_unstable: false,
 551             allow_internal_unsafe: false,
 552             local_inner_macros: false,
 553             edition: ext.edition(),
 554         });
 555
 556         match *ext {
 557             NonMacroAttr { .. } => {
 558                 attr::mark_known(&attr);
 559                 let item = item.map_attrs(|mut attrs| { attrs.push(attr); attrs });
 560                 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
 561             }
 562             MultiModifier(ref mac) => {
 563                 let meta = attr.parse_meta(self.cx.parse_sess)
 564                                .map_err(|mut e| { e.emit(); }).ok()?;
 565                 let item = mac.expand(self.cx, attr.span, &meta, item);
 566                 Some(invoc.fragment_kind.expect_from_annotatables(item))
 567             }
 568             MultiDecorator(ref mac) => {
 569                 let mut items = Vec::new();
 570                 let meta = attr.parse_meta(self.cx.parse_sess)
 571                                .expect("derive meta should already have been parsed");
 572                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 573                 items.push(item);
 574                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 575             }
 576             AttrProcMacro(ref mac, ..) => {
 577                 // Resolve `$crate`s in case we have to go though stringification.
 578                 self.cx.resolver.resolve_dollar_crates(&item);
 579                 self.gate_proc_macro_attr_item(attr.span, &item);
 580                 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
 581                     Annotatable::Item(item) => token::NtItem(item),
 582                     Annotatable::TraitItem(item) => token::NtTraitItem(item.into_inner()),
 583                     Annotatable::ImplItem(item) => token::NtImplItem(item.into_inner()),
 584                     Annotatable::ForeignItem(item) => token::NtForeignItem(item.into_inner()),
 585                     Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
 586                     Annotatable::Expr(expr) => token::NtExpr(expr),
 587                 })).into();
 588                 let input = self.extract_proc_macro_attr_input(attr.tokens, attr.span);
 589                 let tok_result = mac.expand(self.cx, attr.span, input, item_tok);
 590                 let res = self.parse_ast_fragment(tok_result, invoc.fragment_kind,
 591                                                   &attr.path, attr.span);
 592                 self.gate_proc_macro_expansion(attr.span, &res);
 593                 res
 594             }
 595             ProcMacroDerive(..) | BuiltinDerive(..) => {
 596                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 597                 self.cx.trace_macros_diag();
 598                 invoc.fragment_kind.dummy(attr.span)
 599             }
 600             _ => {
 601                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 602                 self.cx.span_err(attr.span, msg);
 603                 self.cx.trace_macros_diag();
 604                 invoc.fragment_kind.dummy(attr.span)
 605             }
 606         }
 607     }
 608
 609     fn extract_proc_macro_attr_input(&self, tokens: TokenStream, span: Span) -> TokenStream {
 610         let mut trees = tokens.trees();
 611         match trees.next() {
 612             Some(TokenTree::Delimited(_, _, tts)) => {
 613                 if trees.next().is_none() {
 614                     return tts.into()
 615                 }
 616             }
 617             Some(TokenTree::Token(..)) => {}
 618             None => return TokenStream::empty(),
 619         }
 620         self.cx.span_err(span, "custom attribute invocations must be \
 621             of the form #[foo] or #[foo(..)], the macro name must only be \
 622             followed by a delimiter token");
 623         TokenStream::empty()
 624     }
 625
 626     fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
 627         let (kind, gate) = match *item {
 628             Annotatable::Item(ref item) => {
 629                 match item.node {
 630                     ItemKind::Mod(_) if self.cx.ecfg.proc_macro_hygiene() => return,
 631                     ItemKind::Mod(_) => ("modules", "proc_macro_hygiene"),
 632                     _ => return,
 633                 }
 634             }
 635             Annotatable::TraitItem(_) => return,
 636             Annotatable::ImplItem(_) => return,
 637             Annotatable::ForeignItem(_) => return,
 638             Annotatable::Stmt(_) |
 639             Annotatable::Expr(_) if self.cx.ecfg.proc_macro_hygiene() => return,
 640             Annotatable::Stmt(_) => ("statements", "proc_macro_hygiene"),
 641             Annotatable::Expr(_) => ("expressions", "proc_macro_hygiene"),
 642         };
 643         emit_feature_err(
 644             self.cx.parse_sess,
 645             gate,
 646             span,
 647             GateIssue::Language,
 648             &format!("custom attributes cannot be applied to {}", kind),
 649         );
 650     }
 651
 652     fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>) {
 653         if self.cx.ecfg.proc_macro_hygiene() {
 654             return
 655         }
 656         let fragment = match fragment {
 657             Some(fragment) => fragment,
 658             None => return,
 659         };
 660
 661         fragment.visit_with(&mut DisallowMacros {
 662             span,
 663             parse_sess: self.cx.parse_sess,
 664         });
 665
 666         struct DisallowMacros<'a> {
 667             span: Span,
 668             parse_sess: &'a ParseSess,
 669         }
 670
 671         impl<'ast, 'a> Visitor<'ast> for DisallowMacros<'a> {
 672             fn visit_item(&mut self, i: &'ast ast::Item) {
 673                 if let ast::ItemKind::MacroDef(_) = i.node {
 674                     emit_feature_err(
 675                         self.parse_sess,
 676                         "proc_macro_hygiene",
 677                         self.span,
 678                         GateIssue::Language,
 679                         "procedural macros cannot expand to macro definitions",
 680                     );
 681                 }
 682                 visit::walk_item(self, i);
 683             }
 684
 685             fn visit_mac(&mut self, _mac: &'ast ast::Mac) {
 686                 // ...
 687             }
 688         }
 689     }
 690
 691     /// Expand a macro invocation. Returns the resulting expanded AST fragment.
 692     fn expand_bang_invoc(&mut self,
 693                          invoc: Invocation,
 694                          ext: &SyntaxExtension)
 695                          -> Option<AstFragment> {
 696         let (mark, kind) = (invoc.expansion_data.mark, invoc.fragment_kind);
 697         let (mac, ident, span) = match invoc.kind {
 698             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 699             _ => unreachable!(),
 700         };
 701         let path = &mac.node.path;
 702
 703         let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
 704         let validate_and_set_expn_info = |this: &mut Self, // arg instead of capture
 705                                           def_site_span: Option<Span>,
 706                                           allow_internal_unstable,
 707                                           allow_internal_unsafe,
 708                                           local_inner_macros,
 709                                           // can't infer this type
 710                                           unstable_feature: Option<(Symbol, u32)>,
 711                                           edition| {
 712
 713             // feature-gate the macro invocation
 714             if let Some((feature, issue)) = unstable_feature {
 715                 let crate_span = this.cx.current_expansion.crate_span.unwrap();
 716                 // don't stability-check macros in the same crate
 717                 // (the only time this is null is for syntax extensions registered as macros)
 718                 if def_site_span.map_or(false, |def_span| !crate_span.contains(def_span))
 719                     && !span.allows_unstable() && this.cx.ecfg.features.map_or(true, |feats| {
 720                     // macro features will count as lib features
 721                     !feats.declared_lib_features.iter().any(|&(feat, _)| feat == feature)
 722                 }) {
 723                     let explain = format!("macro {}! is unstable", path);
 724                     emit_feature_err(this.cx.parse_sess, &*feature.as_str(), span,
 725                                      GateIssue::Library(Some(issue)), &explain);
 726                     this.cx.trace_macros_diag();
 727                 }
 728             }
 729
 730             if ident.name != keywords::Invalid.name() {
 731                 let msg = format!("macro {}! expects no ident argument, given '{}'", path, ident);
 732                 this.cx.span_err(path.span, &msg);
 733                 this.cx.trace_macros_diag();
 734                 return Err(kind.dummy(span));
 735             }
 736             mark.set_expn_info(ExpnInfo {
 737                 call_site: span,
 738                 def_site: def_site_span,
 739                 format: macro_bang_format(path),
 740                 allow_internal_unstable,
 741                 allow_internal_unsafe,
 742                 local_inner_macros,
 743                 edition,
 744             });
 745             Ok(())
 746         };
 747
 748         let opt_expanded = match *ext {
 749             DeclMacro { ref expander, def_info, edition, .. } => {
 750                 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
 751                                                                     false, false, false, None,
 752                                                                     edition) {
 753                     dummy_span
 754                 } else {
 755                     kind.make_from(expander.expand(self.cx, span, mac.node.stream(), None))
 756                 }
 757             }
 758
 759             NormalTT {
 760                 ref expander,
 761                 def_info,
 762                 allow_internal_unstable,
 763                 allow_internal_unsafe,
 764                 local_inner_macros,
 765                 unstable_feature,
 766                 edition,
 767             } => {
 768                 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
 769                                                                     allow_internal_unstable,
 770                                                                     allow_internal_unsafe,
 771                                                                     local_inner_macros,
 772                                                                     unstable_feature,
 773                                                                     edition) {
 774                     dummy_span
 775                 } else {
 776                     kind.make_from(expander.expand(
 777                         self.cx,
 778                         span,
 779                         mac.node.stream(),
 780                         def_info.map(|(_, s)| s),
 781                     ))
 782                 }
 783             }
 784
 785             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 786                 if ident.name == keywords::Invalid.name() {
 787                     self.cx.span_err(path.span,
 788                                     &format!("macro {}! expects an ident argument", path));
 789                     self.cx.trace_macros_diag();
 790                     kind.dummy(span)
 791                 } else {
 792                     invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 793                         call_site: span,
 794                         def_site: tt_span,
 795                         format: macro_bang_format(path),
 796                         allow_internal_unstable,
 797                         allow_internal_unsafe: false,
 798                         local_inner_macros: false,
 799                         edition: hygiene::default_edition(),
 800                     });
 801
 802                     let input: Vec<_> = mac.node.stream().into_trees().collect();
 803                     kind.make_from(expander.expand(self.cx, span, ident, input))
 804                 }
 805             }
 806
 807             MultiDecorator(..) | MultiModifier(..) |
 808             AttrProcMacro(..) | SyntaxExtension::NonMacroAttr { .. } => {
 809                 self.cx.span_err(path.span,
 810                                  &format!("`{}` can only be used in attributes", path));
 811                 self.cx.trace_macros_diag();
 812                 kind.dummy(span)
 813             }
 814
 815             ProcMacroDerive(..) | BuiltinDerive(..) => {
 816                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 817                 self.cx.trace_macros_diag();
 818                 kind.dummy(span)
 819             }
 820
 821             SyntaxExtension::ProcMacro { ref expander, allow_internal_unstable, edition } => {
 822                 if ident.name != keywords::Invalid.name() {
 823                     let msg =
 824                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 825                     self.cx.span_err(path.span, &msg);
 826                     self.cx.trace_macros_diag();
 827                     kind.dummy(span)
 828                 } else {
 829                     self.gate_proc_macro_expansion_kind(span, kind);
 830                     invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 831                         call_site: span,
 832                         // FIXME procedural macros do not have proper span info
 833                         // yet, when they do, we should use it here.
 834                         def_site: None,
 835                         format: macro_bang_format(path),
 836                         // FIXME probably want to follow macro_rules macros here.
 837                         allow_internal_unstable,
 838                         allow_internal_unsafe: false,
 839                         local_inner_macros: false,
 840                         edition,
 841                     });
 842
 843                     let tok_result = expander.expand(self.cx, span, mac.node.stream());
 844                     let result = self.parse_ast_fragment(tok_result, kind, path, span);
 845                     self.gate_proc_macro_expansion(span, &result);
 846                     result
 847                 }
 848             }
 849         };
 850
 851         if opt_expanded.is_some() {
 852             opt_expanded
 853         } else {
 854             let msg = format!("non-{kind} macro in {kind} position: {name}",
 855                               name = path.segments[0].ident.name, kind = kind.name());
 856             self.cx.span_err(path.span, &msg);
 857             self.cx.trace_macros_diag();
 858             kind.dummy(span)
 859         }
 860     }
 861
 862     fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
 863         let kind = match kind {
 864             AstFragmentKind::Expr => "expressions",
 865             AstFragmentKind::OptExpr => "expressions",
 866             AstFragmentKind::Pat => "patterns",
 867             AstFragmentKind::Ty => "types",
 868             AstFragmentKind::Stmts => "statements",
 869             AstFragmentKind::Items => return,
 870             AstFragmentKind::TraitItems => return,
 871             AstFragmentKind::ImplItems => return,
 872             AstFragmentKind::ForeignItems => return,
 873         };
 874         if self.cx.ecfg.proc_macro_hygiene() {
 875             return
 876         }
 877         emit_feature_err(
 878             self.cx.parse_sess,
 879             "proc_macro_hygiene",
 880             span,
 881             GateIssue::Language,
 882             &format!("procedural macros cannot be expanded to {}", kind),
 883         );
 884     }
 885
 886     /// Expand a derive invocation. Returns the resulting expanded AST fragment.
 887     fn expand_derive_invoc(&mut self,
 888                            invoc: Invocation,
 889                            ext: &SyntaxExtension)
 890                            -> Option<AstFragment> {
 891         let (path, item) = match invoc.kind {
 892             InvocationKind::Derive { path, item } => (path, item),
 893             _ => unreachable!(),
 894         };
 895         if !item.derive_allowed() {
 896             return None;
 897         }
 898
 899         let pretty_name = Symbol::intern(&format!("derive({})", path));
 900         let span = path.span;
 901         let attr = ast::Attribute {
 902             path, span,
 903             tokens: TokenStream::empty(),
 904             // irrelevant:
 905             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 906         };
 907
 908         let mut expn_info = ExpnInfo {
 909             call_site: span,
 910             def_site: None,
 911             format: MacroAttribute(pretty_name),
 912             allow_internal_unstable: false,
 913             allow_internal_unsafe: false,
 914             local_inner_macros: false,
 915             edition: ext.edition(),
 916         };
 917
 918         match *ext {
 919             ProcMacroDerive(ref ext, ..) => {
 920                 // Resolve `$crate`s in case we have to go though stringification.
 921                 self.cx.resolver.resolve_dollar_crates(&item);
 922                 invoc.expansion_data.mark.set_expn_info(expn_info);
 923                 let span = span.with_ctxt(self.cx.backtrace());
 924                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 925                     ident: Path::from_ident(keywords::Invalid.ident()),
 926                     span: DUMMY_SP,
 927                     node: ast::MetaItemKind::Word,
 928                 };
 929                 let items = ext.expand(self.cx, span, &dummy, item);
 930                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 931             }
 932             BuiltinDerive(func) => {
 933                 expn_info.allow_internal_unstable = true;
 934                 invoc.expansion_data.mark.set_expn_info(expn_info);
 935                 let span = span.with_ctxt(self.cx.backtrace());
 936                 let mut items = Vec::new();
 937                 func(self.cx, span, &attr.meta()?, &item, &mut |a| items.push(a));
 938                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 939             }
 940             _ => {
 941                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 942                 self.cx.span_err(span, msg);
 943                 self.cx.trace_macros_diag();
 944                 invoc.fragment_kind.dummy(span)
 945             }
 946         }
 947     }
 948
 949     fn parse_ast_fragment(&mut self,
 950                           toks: TokenStream,
 951                           kind: AstFragmentKind,
 952                           path: &Path,
 953                           span: Span)
 954                           -> Option<AstFragment> {
 955         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 956         match parser.parse_ast_fragment(kind, false) {
 957             Ok(fragment) => {
 958                 parser.ensure_complete_parse(path, kind.name(), span);
 959                 Some(fragment)
 960             }
 961             Err(mut err) => {
 962                 err.set_span(span);
 963                 err.emit();
 964                 self.cx.trace_macros_diag();
 965                 kind.dummy(span)
 966             }
 967         }
 968     }
 969 }
 970
 971 impl<'a> Parser<'a> {
 972     pub fn parse_ast_fragment(&mut self, kind: AstFragmentKind, macro_legacy_warnings: bool)
 973                               -> PResult<'a, AstFragment> {
 974         Ok(match kind {
 975             AstFragmentKind::Items => {
 976                 let mut items = SmallVec::new();
 977                 while let Some(item) = self.parse_item()? {
 978                     items.push(item);
 979                 }
 980                 AstFragment::Items(items)
 981             }
 982             AstFragmentKind::TraitItems => {
 983                 let mut items = SmallVec::new();
 984                 while self.token != token::Eof {
 985                     items.push(self.parse_trait_item(&mut false)?);
 986                 }
 987                 AstFragment::TraitItems(items)
 988             }
 989             AstFragmentKind::ImplItems => {
 990                 let mut items = SmallVec::new();
 991                 while self.token != token::Eof {
 992                     items.push(self.parse_impl_item(&mut false)?);
 993                 }
 994                 AstFragment::ImplItems(items)
 995             }
 996             AstFragmentKind::ForeignItems => {
 997                 let mut items = SmallVec::new();
 998                 while self.token != token::Eof {
 999                     items.push(self.parse_foreign_item()?);
1000                 }
1001                 AstFragment::ForeignItems(items)
1002             }
1003             AstFragmentKind::Stmts => {
1004                 let mut stmts = SmallVec::new();
1005                 while self.token != token::Eof &&
1006                       // won't make progress on a `}`
1007                       self.token != token::CloseDelim(token::Brace) {
1008                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
1009                         stmts.push(stmt);
1010                     }
1011                 }
1012                 AstFragment::Stmts(stmts)
1013             }
1014             AstFragmentKind::Expr => AstFragment::Expr(self.parse_expr()?),
1015             AstFragmentKind::OptExpr => {
1016                 if self.token != token::Eof {
1017                     AstFragment::OptExpr(Some(self.parse_expr()?))
1018                 } else {
1019                     AstFragment::OptExpr(None)
1020                 }
1021             },
1022             AstFragmentKind::Ty => AstFragment::Ty(self.parse_ty()?),
1023             AstFragmentKind::Pat => AstFragment::Pat(self.parse_pat(None)?),
1024         })
1025     }
1026
1027     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
1028         if self.token != token::Eof {
1029             let msg = format!("macro expansion ignores token `{}` and any following",
1030                               self.this_token_to_string());
1031             // Avoid emitting backtrace info twice.
1032             let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
1033             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
1034             err.span_label(span, "caused by the macro expansion here");
1035             let msg = format!(
1036                 "the usage of `{}!` is likely invalid in {} context",
1037                 macro_path,
1038                 kind_name,
1039             );
1040             err.note(&msg);
1041             let semi_span = self.sess.source_map().next_point(span);
1042
1043             let semi_full_span = semi_span.to(self.sess.source_map().next_point(semi_span));
1044             match self.sess.source_map().span_to_snippet(semi_full_span) {
1045                 Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
1046                     err.span_suggestion_with_applicability(
1047                         semi_span,
1048                         "you might be missing a semicolon here",
1049                         ";".to_owned(),
1050                         Applicability::MaybeIncorrect,
1051                     );
1052                 }
1053                 _ => {}
1054             }
1055             err.emit();
1056         }
1057     }
1058 }
1059
1060 struct InvocationCollector<'a, 'b: 'a> {
1061     cx: &'a mut ExtCtxt<'b>,
1062     cfg: StripUnconfigured<'a>,
1063     invocations: Vec<Invocation>,
1064     monotonic: bool,
1065 }
1066
1067 impl<'a, 'b> InvocationCollector<'a, 'b> {
1068     fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
1069         let mark = Mark::fresh(self.cx.current_expansion.mark);
1070         self.invocations.push(Invocation {
1071             kind,
1072             fragment_kind,
1073             expansion_data: ExpansionData {
1074                 mark,
1075                 depth: self.cx.current_expansion.depth + 1,
1076                 ..self.cx.current_expansion.clone()
1077             },
1078         });
1079         placeholder(fragment_kind, NodeId::placeholder_from_mark(mark))
1080     }
1081
1082     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
1083         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
1084     }
1085
1086     fn collect_attr(&mut self,
1087                     attr: Option<ast::Attribute>,
1088                     traits: Vec<Path>,
1089                     item: Annotatable,
1090                     kind: AstFragmentKind,
1091                     after_derive: bool)
1092                     -> AstFragment {
1093         self.collect(kind, InvocationKind::Attr { attr, traits, item, after_derive })
1094     }
1095
1096     fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, after_derive: &mut bool)
1097                        -> Option<ast::Attribute> {
1098         let attr = attrs.iter()
1099                         .position(|a| {
1100                             if a.path == "derive" {
1101                                 *after_derive = true;
1102                             }
1103                             !attr::is_known(a) && !is_builtin_attr(a)
1104                         })
1105                         .map(|i| attrs.remove(i));
1106         if let Some(attr) = &attr {
1107             if !self.cx.ecfg.enable_custom_inner_attributes() &&
1108                attr.style == ast::AttrStyle::Inner && attr.path != "test" {
1109                 emit_feature_err(&self.cx.parse_sess, "custom_inner_attributes",
1110                                  attr.span, GateIssue::Language,
1111                                  "non-builtin inner attributes are unstable");
1112             }
1113         }
1114         attr
1115     }
1116
1117     /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
1118     fn classify_item<T>(&mut self, mut item: T)
1119                         -> (Option<ast::Attribute>, Vec<Path>, T, /* after_derive */ bool)
1120         where T: HasAttrs,
1121     {
1122         let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
1123
1124         item = item.map_attrs(|mut attrs| {
1125             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1126             traits = collect_derives(&mut self.cx, &mut attrs);
1127             attrs
1128         });
1129
1130         (attr, traits, item, after_derive)
1131     }
1132
1133     /// Alternative of `classify_item()` that ignores `#[derive]` so invocations fallthrough
1134     /// to the unused-attributes lint (making it an error on statements and expressions
1135     /// is a breaking change)
1136     fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T)
1137                                      -> (Option<ast::Attribute>, T, /* after_derive */ bool) {
1138         let (mut attr, mut after_derive) = (None, false);
1139
1140         item = item.map_attrs(|mut attrs| {
1141             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1142             attrs
1143         });
1144
1145         (attr, item, after_derive)
1146     }
1147
1148     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
1149         self.cfg.configure(node)
1150     }
1151
1152     // Detect use of feature-gated or invalid attributes on macro invocations
1153     // since they will not be detected after macro expansion.
1154     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
1155         let features = self.cx.ecfg.features.unwrap();
1156         for attr in attrs.iter() {
1157             self.check_attribute_inner(attr, features);
1158
1159             // macros are expanded before any lint passes so this warning has to be hardcoded
1160             if attr.path == "derive" {
1161                 self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
1162                     .note("this may become a hard error in a future release")
1163                     .emit();
1164             }
1165         }
1166     }
1167
1168     fn check_attribute(&mut self, at: &ast::Attribute) {
1169         let features = self.cx.ecfg.features.unwrap();
1170         self.check_attribute_inner(at, features);
1171     }
1172
1173     fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
1174         feature_gate::check_attribute(at, self.cx.parse_sess, features);
1175     }
1176 }
1177
1178 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
1179     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
1180         let expr = self.cfg.configure_expr(expr);
1181         expr.map(|mut expr| {
1182             expr.node = self.cfg.configure_expr_kind(expr.node);
1183
1184             // ignore derives so they remain unused
1185             let (attr, expr, after_derive) = self.classify_nonitem(expr);
1186
1187             if attr.is_some() {
1188                 // Collect the invoc regardless of whether or not attributes are permitted here
1189                 // expansion will eat the attribute so it won't error later.
1190                 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1191
1192                 // AstFragmentKind::Expr requires the macro to emit an expression.
1193                 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1194                                          AstFragmentKind::Expr, after_derive)
1195                     .make_expr()
1196                     .into_inner()
1197             }
1198
1199             if let ast::ExprKind::Mac(mac) = expr.node {
1200                 self.check_attributes(&expr.attrs);
1201                 self.collect_bang(mac, expr.span, AstFragmentKind::Expr)
1202                     .make_expr()
1203                     .into_inner()
1204             } else {
1205                 noop_fold_expr(expr, self)
1206             }
1207         })
1208     }
1209
1210     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
1211         let expr = configure!(self, expr);
1212         expr.filter_map(|mut expr| {
1213             expr.node = self.cfg.configure_expr_kind(expr.node);
1214
1215             // Ignore derives so they remain unused.
1216             let (attr, expr, after_derive) = self.classify_nonitem(expr);
1217
1218             if attr.is_some() {
1219                 attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1220
1221                 return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1222                                          AstFragmentKind::OptExpr, after_derive)
1223                     .make_opt_expr()
1224                     .map(|expr| expr.into_inner())
1225             }
1226
1227             if let ast::ExprKind::Mac(mac) = expr.node {
1228                 self.check_attributes(&expr.attrs);
1229                 self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
1230                     .make_opt_expr()
1231                     .map(|expr| expr.into_inner())
1232             } else {
1233                 Some(noop_fold_expr(expr, self))
1234             }
1235         })
1236     }
1237
1238     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
1239         let pat = self.cfg.configure_pat(pat);
1240         match pat.node {
1241             PatKind::Mac(_) => {}
1242             _ => return noop_fold_pat(pat, self),
1243         }
1244
1245         pat.and_then(|pat| match pat.node {
1246             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
1247             _ => unreachable!(),
1248         })
1249     }
1250
1251     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
1252         let mut stmt = match self.cfg.configure_stmt(stmt) {
1253             Some(stmt) => stmt,
1254             None => return SmallVec::new(),
1255         };
1256
1257         // we'll expand attributes on expressions separately
1258         if !stmt.is_expr() {
1259             let (attr, derives, stmt_, after_derive) = if stmt.is_item() {
1260                 self.classify_item(stmt)
1261             } else {
1262                 // ignore derives on non-item statements so it falls through
1263                 // to the unused-attributes lint
1264                 let (attr, stmt, after_derive) = self.classify_nonitem(stmt);
1265                 (attr, vec![], stmt, after_derive)
1266             };
1267
1268             if attr.is_some() || !derives.is_empty() {
1269                 return self.collect_attr(attr, derives, Annotatable::Stmt(P(stmt_)),
1270                                          AstFragmentKind::Stmts, after_derive).make_stmts();
1271             }
1272
1273             stmt = stmt_;
1274         }
1275
1276         if let StmtKind::Mac(mac) = stmt.node {
1277             let (mac, style, attrs) = mac.into_inner();
1278             self.check_attributes(&attrs);
1279             let mut placeholder = self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts)
1280                                         .make_stmts();
1281
1282             // If this is a macro invocation with a semicolon, then apply that
1283             // semicolon to the final statement produced by expansion.
1284             if style == MacStmtStyle::Semicolon {
1285                 if let Some(stmt) = placeholder.pop() {
1286                     placeholder.push(stmt.add_trailing_semicolon());
1287                 }
1288             }
1289
1290             return placeholder;
1291         }
1292
1293         // The placeholder expander gives ids to statements, so we avoid folding the id here.
1294         let ast::Stmt { id, node, span } = stmt;
1295         noop_fold_stmt_kind(node, self).into_iter().map(|node| {
1296             ast::Stmt { id, node, span }
1297         }).collect()
1298
1299     }
1300
1301     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
1302         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
1303         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
1304         let result = noop_fold_block(block, self);
1305         self.cx.current_expansion.directory_ownership = old_directory_ownership;
1306         result
1307     }
1308
1309     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
1310         let item = configure!(self, item);
1311
1312         let (attr, traits, item, after_derive) = self.classify_item(item);
1313         if attr.is_some() || !traits.is_empty() {
1314             return self.collect_attr(attr, traits, Annotatable::Item(item),
1315                                      AstFragmentKind::Items, after_derive).make_items();
1316         }
1317
1318         match item.node {
1319             ast::ItemKind::Mac(..) => {
1320                 self.check_attributes(&item.attrs);
1321                 item.and_then(|item| match item.node {
1322                     ItemKind::Mac(mac) => {
1323                         self.collect(AstFragmentKind::Items, InvocationKind::Bang {
1324                             mac,
1325                             ident: Some(item.ident),
1326                             span: item.span,
1327                         }).make_items()
1328                     }
1329                     _ => unreachable!(),
1330                 })
1331             }
1332             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
1333                 if item.ident == keywords::Invalid.ident() {
1334                     return noop_fold_item(item, self);
1335                 }
1336
1337                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
1338                 let mut module = (*self.cx.current_expansion.module).clone();
1339                 module.mod_path.push(item.ident);
1340
1341                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
1342                 // In the non-inline case, `inner` is never the dummy span (cf. `parse_item_mod`).
1343                 // Thus, if `inner` is the dummy span, we know the module is inline.
1344                 let inline_module = item.span.contains(inner) || inner.is_dummy();
1345
1346                 if inline_module {
1347                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
1348                         self.cx.current_expansion.directory_ownership =
1349                             DirectoryOwnership::Owned { relative: None };
1350                         module.directory.push(&*path.as_str());
1351                     } else {
1352                         module.directory.push(&*item.ident.as_str());
1353                     }
1354                 } else {
1355                     let path = self.cx.parse_sess.source_map().span_to_unmapped_path(inner);
1356                     let mut path = match path {
1357                         FileName::Real(path) => path,
1358                         other => PathBuf::from(other.to_string()),
1359                     };
1360                     let directory_ownership = match path.file_name().unwrap().to_str() {
1361                         Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
1362                         Some(_) => DirectoryOwnership::Owned {
1363                             relative: Some(item.ident),
1364                         },
1365                         None => DirectoryOwnership::UnownedViaMod(false),
1366                     };
1367                     path.pop();
1368                     module.directory = path;
1369                     self.cx.current_expansion.directory_ownership = directory_ownership;
1370                 }
1371
1372                 let orig_module =
1373                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
1374                 let result = noop_fold_item(item, self);
1375                 self.cx.current_expansion.module = orig_module;
1376                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
1377                 result
1378             }
1379
1380             _ => noop_fold_item(item, self),
1381         }
1382     }
1383
1384     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
1385         let item = configure!(self, item);
1386
1387         let (attr, traits, item, after_derive) = self.classify_item(item);
1388         if attr.is_some() || !traits.is_empty() {
1389             return self.collect_attr(attr, traits, Annotatable::TraitItem(P(item)),
1390                                      AstFragmentKind::TraitItems, after_derive).make_trait_items()
1391         }
1392
1393         match item.node {
1394             ast::TraitItemKind::Macro(mac) => {
1395                 let ast::TraitItem { attrs, span, .. } = item;
1396                 self.check_attributes(&attrs);
1397                 self.collect_bang(mac, span, AstFragmentKind::TraitItems).make_trait_items()
1398             }
1399             _ => fold::noop_fold_trait_item(item, self),
1400         }
1401     }
1402
1403     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
1404         let item = configure!(self, item);
1405
1406         let (attr, traits, item, after_derive) = self.classify_item(item);
1407         if attr.is_some() || !traits.is_empty() {
1408             return self.collect_attr(attr, traits, Annotatable::ImplItem(P(item)),
1409                                      AstFragmentKind::ImplItems, after_derive).make_impl_items();
1410         }
1411
1412         match item.node {
1413             ast::ImplItemKind::Macro(mac) => {
1414                 let ast::ImplItem { attrs, span, .. } = item;
1415                 self.check_attributes(&attrs);
1416                 self.collect_bang(mac, span, AstFragmentKind::ImplItems).make_impl_items()
1417             }
1418             _ => fold::noop_fold_impl_item(item, self),
1419         }
1420     }
1421
1422     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1423         let ty = match ty.node {
1424             ast::TyKind::Mac(_) => ty.into_inner(),
1425             _ => return fold::noop_fold_ty(ty, self),
1426         };
1427
1428         match ty.node {
1429             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
1430             _ => unreachable!(),
1431         }
1432     }
1433
1434     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1435         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1436     }
1437
1438     fn fold_foreign_item(&mut self, foreign_item: ast::ForeignItem)
1439         -> SmallVec<[ast::ForeignItem; 1]>
1440     {
1441         let (attr, traits, foreign_item, after_derive) = self.classify_item(foreign_item);
1442
1443         if attr.is_some() || !traits.is_empty() {
1444             return self.collect_attr(attr, traits, Annotatable::ForeignItem(P(foreign_item)),
1445                                      AstFragmentKind::ForeignItems, after_derive)
1446                                      .make_foreign_items();
1447         }
1448
1449         if let ast::ForeignItemKind::Macro(mac) = foreign_item.node {
1450             self.check_attributes(&foreign_item.attrs);
1451             return self.collect_bang(mac, foreign_item.span, AstFragmentKind::ForeignItems)
1452                 .make_foreign_items();
1453         }
1454
1455         noop_fold_foreign_item(foreign_item, self)
1456     }
1457
1458     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1459         match item {
1460             ast::ItemKind::MacroDef(..) => item,
1461             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1462         }
1463     }
1464
1465     fn fold_generic_param(&mut self, param: ast::GenericParam) -> ast::GenericParam {
1466         self.cfg.disallow_cfg_on_generic_param(&param);
1467         noop_fold_generic_param(param, self)
1468     }
1469
1470     fn fold_attribute(&mut self, at: ast::Attribute) -> Option<ast::Attribute> {
1471         // turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
1472         // contents="file contents")]` attributes
1473         if !at.check_name("doc") {
1474             return noop_fold_attribute(at, self);
1475         }
1476
1477         if let Some(list) = at.meta_item_list() {
1478             if !list.iter().any(|it| it.check_name("include")) {
1479                 return noop_fold_attribute(at, self);
1480             }
1481
1482             let mut items = vec![];
1483
1484             for it in list {
1485                 if !it.check_name("include") {
1486                     items.push(noop_fold_meta_list_item(it, self));
1487                     continue;
1488                 }
1489
1490                 if let Some(file) = it.value_str() {
1491                     let err_count = self.cx.parse_sess.span_diagnostic.err_count();
1492                     self.check_attribute(&at);
1493                     if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
1494                         // avoid loading the file if they haven't enabled the feature
1495                         return noop_fold_attribute(at, self);
1496                     }
1497
1498                     let filename = self.cx.root_path.join(file.to_string());
1499                     match fs::read_to_string(&filename) {
1500                         Ok(src) => {
1501                             let src_interned = Symbol::intern(&src);
1502
1503                             // Add this input file to the code map to make it available as
1504                             // dependency information
1505                             self.cx.source_map().new_source_file(filename.into(), src);
1506
1507                             let include_info = vec![
1508                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1509                                     attr::mk_name_value_item_str(
1510                                         Ident::from_str("file"),
1511                                         dummy_spanned(file),
1512                                     ),
1513                                 )),
1514                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1515                                     attr::mk_name_value_item_str(
1516                                         Ident::from_str("contents"),
1517                                         dummy_spanned(src_interned),
1518                                     ),
1519                                 )),
1520                             ];
1521
1522                             let include_ident = Ident::from_str("include");
1523                             let item = attr::mk_list_item(DUMMY_SP, include_ident, include_info);
1524                             items.push(dummy_spanned(ast::NestedMetaItemKind::MetaItem(item)));
1525                         }
1526                         Err(e) => {
1527                             let lit = it
1528                                 .meta_item()
1529                                 .and_then(|item| item.name_value_literal())
1530                                 .unwrap();
1531
1532                             if e.kind() == ErrorKind::InvalidData {
1533                                 self.cx
1534                                     .struct_span_err(
1535                                         lit.span,
1536                                         &format!("{} wasn't a utf-8 file", filename.display()),
1537                                     )
1538                                     .span_label(lit.span, "contains invalid utf-8")
1539                                     .emit();
1540                             } else {
1541                                 let mut err = self.cx.struct_span_err(
1542                                     lit.span,
1543                                     &format!("couldn't read {}: {}", filename.display(), e),
1544                                 );
1545                                 err.span_label(lit.span, "couldn't read file");
1546
1547                                 if e.kind() == ErrorKind::NotFound {
1548                                     err.help("external doc paths are relative to the crate root");
1549                                 }
1550
1551                                 err.emit();
1552                             }
1553                         }
1554                     }
1555                 } else {
1556                     let mut err = self.cx.struct_span_err(
1557                         it.span,
1558                         &format!("expected path to external documentation"),
1559                     );
1560
1561                     // Check if the user erroneously used `doc(include(...))` syntax.
1562                     let literal = it.meta_item_list().and_then(|list| {
1563                         if list.len() == 1 {
1564                             list[0].literal().map(|literal| &literal.node)
1565                         } else {
1566                             None
1567                         }
1568                     });
1569
1570                     let (path, applicability) = match &literal {
1571                         Some(LitKind::Str(path, ..)) => {
1572                             (path.to_string(), Applicability::MachineApplicable)
1573                         }
1574                         _ => (String::from("<path>"), Applicability::HasPlaceholders),
1575                     };
1576
1577                     err.span_suggestion_with_applicability(
1578                         it.span,
1579                         "provide a file path with `=`",
1580                         format!("include = \"{}\"", path),
1581                         applicability,
1582                     );
1583
1584                     err.emit();
1585                 }
1586             }
1587
1588             let meta = attr::mk_list_item(DUMMY_SP, Ident::from_str("doc"), items);
1589             match at.style {
1590                 ast::AttrStyle::Inner =>
1591                     Some(attr::mk_spanned_attr_inner(at.span, at.id, meta)),
1592                 ast::AttrStyle::Outer =>
1593                     Some(attr::mk_spanned_attr_outer(at.span, at.id, meta)),
1594             }
1595         } else {
1596             noop_fold_attribute(at, self)
1597         }
1598     }
1599
1600     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1601         if self.monotonic {
1602             assert_eq!(id, ast::DUMMY_NODE_ID);
1603             self.cx.resolver.next_node_id()
1604         } else {
1605             id
1606         }
1607     }
1608 }
1609
1610 pub struct ExpansionConfig<'feat> {
1611     pub crate_name: String,
1612     pub features: Option<&'feat Features>,
1613     pub recursion_limit: usize,
1614     pub trace_mac: bool,
1615     pub should_test: bool, // If false, strip `#[test]` nodes
1616     pub single_step: bool,
1617     pub keep_macs: bool,
1618 }
1619
1620 macro_rules! feature_tests {
1621     ($( fn $getter:ident = $field:ident, )*) => {
1622         $(
1623             pub fn $getter(&self) -> bool {
1624                 match self.features {
1625                     Some(&Features { $field: true, .. }) => true,
1626                     _ => false,
1627                 }
1628             }
1629         )*
1630     }
1631 }
1632
1633 impl<'feat> ExpansionConfig<'feat> {
1634     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1635         ExpansionConfig {
1636             crate_name,
1637             features: None,
1638             recursion_limit: 1024,
1639             trace_mac: false,
1640             should_test: false,
1641             single_step: false,
1642             keep_macs: false,
1643         }
1644     }
1645
1646     feature_tests! {
1647         fn enable_asm = asm,
1648         fn enable_custom_test_frameworks = custom_test_frameworks,
1649         fn enable_global_asm = global_asm,
1650         fn enable_log_syntax = log_syntax,
1651         fn enable_concat_idents = concat_idents,
1652         fn enable_trace_macros = trace_macros,
1653         fn enable_allow_internal_unstable = allow_internal_unstable,
1654         fn enable_format_args_nl = format_args_nl,
1655         fn macros_in_extern_enabled = macros_in_extern,
1656         fn proc_macro_hygiene = proc_macro_hygiene,
1657     }
1658
1659     fn enable_custom_inner_attributes(&self) -> bool {
1660         self.features.map_or(false, |features| {
1661             features.custom_inner_attributes || features.custom_attribute || features.rustc_attrs
1662         })
1663     }
1664 }
1665
1666 // A Marker adds the given mark to the syntax context.
1667 #[derive(Debug)]
1668 pub struct Marker(pub Mark);
1669
1670 impl Folder for Marker {
1671     fn new_span(&mut self, span: Span) -> Span {
1672         span.apply_mark(self.0)
1673     }
1674
1675     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1676         noop_fold_mac(mac, self)
1677     }
1678 }