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