src/libsyntax/ext/expand.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ast::{self, Block, Ident, NodeId, PatKind, Path};
  12 use ast::{MacStmtStyle, StmtKind, ItemKind};
  13 use attr::{self, HasAttrs};
  14 use source_map::{ExpnInfo, MacroBang, MacroAttribute, dummy_spanned, respan};
  15 use config::StripUnconfigured;
  16 use errors::{Applicability, FatalError};
  17 use ext::base::*;
  18 use ext::derive::{add_derived_markers, collect_derives};
  19 use ext::hygiene::{self, Mark, SyntaxContext};
  20 use ext::placeholders::{placeholder, PlaceholderExpander};
  21 use feature_gate::{self, Features, GateIssue, is_builtin_attr, emit_feature_err};
  22 use fold;
  23 use fold::*;
  24 use parse::{DirectoryOwnership, PResult, ParseSess};
  25 use parse::token::{self, Token};
  26 use parse::parser::Parser;
  27 use ptr::P;
  28 use smallvec::SmallVec;
  29 use symbol::Symbol;
  30 use symbol::keywords;
  31 use syntax_pos::{Span, DUMMY_SP, FileName};
  32 use syntax_pos::hygiene::ExpnFormat;
  33 use tokenstream::{TokenStream, TokenTree};
  34 use visit::{self, Visitor};
  35
  36 use rustc_data_structures::fx::FxHashMap;
  37 use std::fs::File;
  38 use std::io::Read;
  39 use std::{iter, mem};
  40 use std::rc::Rc;
  41 use std::path::PathBuf;
  42
  43 macro_rules! ast_fragments {
  44     (
  45         $($Kind:ident($AstTy:ty) {
  46             $kind_name:expr;
  47             // FIXME: HACK: this should be `$(one ...)?` and `$(many ...)?` but `?` macro
  48             // repetition was removed from 2015 edition in #51587 because of ambiguities.
  49             $(one fn $fold_ast:ident; fn $visit_ast:ident;)*
  50             $(many fn $fold_ast_elt:ident; fn $visit_ast_elt:ident;)*
  51             fn $make_ast:ident;
  52         })*
  53     ) => {
  54         /// A fragment of AST that can be produced by a single macro expansion.
  55         /// Can also serve as an input and intermediate result for macro expansion operations.
  56         pub enum AstFragment {
  57             OptExpr(Option<P<ast::Expr>>),
  58             $($Kind($AstTy),)*
  59         }
  60
  61         /// "Discriminant" of an AST fragment.
  62         #[derive(Copy, Clone, PartialEq, Eq)]
  63         pub enum AstFragmentKind {
  64             OptExpr,
  65             $($Kind,)*
  66         }
  67
  68         impl AstFragmentKind {
  69             pub fn name(self) -> &'static str {
  70                 match self {
  71                     AstFragmentKind::OptExpr => "expression",
  72                     $(AstFragmentKind::$Kind => $kind_name,)*
  73                 }
  74             }
  75
  76             fn make_from<'a>(self, result: Box<dyn MacResult + 'a>) -> Option<AstFragment> {
  77                 match self {
  78                     AstFragmentKind::OptExpr =>
  79                         result.make_expr().map(Some).map(AstFragment::OptExpr),
  80                     $(AstFragmentKind::$Kind => result.$make_ast().map(AstFragment::$Kind),)*
  81                 }
  82             }
  83         }
  84
  85         impl AstFragment {
  86             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  87                 match self {
  88                     AstFragment::OptExpr(expr) => expr,
  89                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
  90                 }
  91             }
  92
  93             $(pub fn $make_ast(self) -> $AstTy {
  94                 match self {
  95                     AstFragment::$Kind(ast) => ast,
  96                     _ => panic!("AstFragment::make_* called on the wrong kind of fragment"),
  97                 }
  98             })*
  99
 100             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
 101                 match self {
 102                     AstFragment::OptExpr(expr) =>
 103                         AstFragment::OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
 104                     $($(AstFragment::$Kind(ast) =>
 105                         AstFragment::$Kind(folder.$fold_ast(ast)),)*)*
 106                     $($(AstFragment::$Kind(ast) =>
 107                         AstFragment::$Kind(ast.into_iter()
 108                                               .flat_map(|ast| folder.$fold_ast_elt(ast))
 109                                               .collect()),)*)*
 110                 }
 111             }
 112
 113             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
 114                 match *self {
 115                     AstFragment::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
 116                     AstFragment::OptExpr(None) => {}
 117                     $($(AstFragment::$Kind(ref ast) => visitor.$visit_ast(ast),)*)*
 118                     $($(AstFragment::$Kind(ref ast) => for ast_elt in &ast[..] {
 119                         visitor.$visit_ast_elt(ast_elt);
 120                     })*)*
 121                 }
 122             }
 123         }
 124
 125         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 126             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 127                 self.expand_fragment(AstFragment::OptExpr(Some(expr))).make_opt_expr()
 128             }
 129             $($(fn $fold_ast(&mut self, ast: $AstTy) -> $AstTy {
 130                 self.expand_fragment(AstFragment::$Kind(ast)).$make_ast()
 131             })*)*
 132             $($(fn $fold_ast_elt(&mut self, ast_elt: <$AstTy as IntoIterator>::Item) -> $AstTy {
 133                 self.expand_fragment(AstFragment::$Kind(smallvec![ast_elt])).$make_ast()
 134             })*)*
 135         }
 136
 137         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 138             $(fn $make_ast(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>)
 139                            -> Option<$AstTy> {
 140                 Some(self.make(AstFragmentKind::$Kind).$make_ast())
 141             })*
 142         }
 143     }
 144 }
 145
 146 ast_fragments! {
 147     Expr(P<ast::Expr>) { "expression"; one fn fold_expr; fn visit_expr; fn make_expr; }
 148     Pat(P<ast::Pat>) { "pattern"; one fn fold_pat; fn visit_pat; fn make_pat; }
 149     Ty(P<ast::Ty>) { "type"; one fn fold_ty; fn visit_ty; fn make_ty; }
 150     Stmts(SmallVec<[ast::Stmt; 1]>) {
 151         "statement"; many fn fold_stmt; fn visit_stmt; fn make_stmts;
 152     }
 153     Items(SmallVec<[P<ast::Item>; 1]>) {
 154         "item"; many fn fold_item; fn visit_item; fn make_items;
 155     }
 156     TraitItems(SmallVec<[ast::TraitItem; 1]>) {
 157         "trait item"; many fn fold_trait_item; fn visit_trait_item; fn make_trait_items;
 158     }
 159     ImplItems(SmallVec<[ast::ImplItem; 1]>) {
 160         "impl item"; many fn fold_impl_item; fn visit_impl_item; fn make_impl_items;
 161     }
 162     ForeignItems(SmallVec<[ast::ForeignItem; 1]>) {
 163         "foreign item"; many fn fold_foreign_item; fn visit_foreign_item; fn make_foreign_items;
 164     }
 165 }
 166
 167 impl AstFragmentKind {
 168     fn dummy(self, span: Span) -> Option<AstFragment> {
 169         self.make_from(DummyResult::any(span))
 170     }
 171
 172     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I)
 173                                                                      -> AstFragment {
 174         let mut items = items.into_iter();
 175         match self {
 176             AstFragmentKind::Items =>
 177                 AstFragment::Items(items.map(Annotatable::expect_item).collect()),
 178             AstFragmentKind::ImplItems =>
 179                 AstFragment::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 180             AstFragmentKind::TraitItems =>
 181                 AstFragment::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 182             AstFragmentKind::ForeignItems =>
 183                 AstFragment::ForeignItems(items.map(Annotatable::expect_foreign_item).collect()),
 184             AstFragmentKind::Stmts =>
 185                 AstFragment::Stmts(items.map(Annotatable::expect_stmt).collect()),
 186             AstFragmentKind::Expr => AstFragment::Expr(
 187                 items.next().expect("expected exactly one expression").expect_expr()
 188             ),
 189             AstFragmentKind::OptExpr =>
 190                 AstFragment::OptExpr(items.next().map(Annotatable::expect_expr)),
 191             AstFragmentKind::Pat | AstFragmentKind::Ty =>
 192                 panic!("patterns and types aren't annotatable"),
 193         }
 194     }
 195 }
 196
 197 fn macro_bang_format(path: &ast::Path) -> ExpnFormat {
 198     // We don't want to format a path using pretty-printing,
 199     // `format!("{}", path)`, because that tries to insert
 200     // line-breaks and is slow.
 201     let mut path_str = String::with_capacity(64);
 202     for (i, segment) in path.segments.iter().enumerate() {
 203         if i != 0 {
 204             path_str.push_str("::");
 205         }
 206
 207         if segment.ident.name != keywords::CrateRoot.name() &&
 208             segment.ident.name != keywords::DollarCrate.name()
 209         {
 210             path_str.push_str(&segment.ident.as_str())
 211         }
 212     }
 213
 214     MacroBang(Symbol::intern(&path_str))
 215 }
 216
 217 pub struct Invocation {
 218     pub kind: InvocationKind,
 219     fragment_kind: AstFragmentKind,
 220     pub expansion_data: ExpansionData,
 221 }
 222
 223 pub enum InvocationKind {
 224     Bang {
 225         mac: ast::Mac,
 226         ident: Option<Ident>,
 227         span: Span,
 228     },
 229     Attr {
 230         attr: Option<ast::Attribute>,
 231         traits: Vec<Path>,
 232         item: Annotatable,
 233         // We temporarily report errors for attribute macros placed after derives
 234         after_derive: bool,
 235     },
 236     Derive {
 237         path: Path,
 238         item: Annotatable,
 239     },
 240 }
 241
 242 impl Invocation {
 243     pub fn span(&self) -> Span {
 244         match self.kind {
 245             InvocationKind::Bang { span, .. } => span,
 246             InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
 247             InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
 248             InvocationKind::Derive { ref path, .. } => path.span,
 249         }
 250     }
 251 }
 252
 253 pub struct MacroExpander<'a, 'b:'a> {
 254     pub cx: &'a mut ExtCtxt<'b>,
 255     monotonic: bool, // c.f. `cx.monotonic_expander()`
 256 }
 257
 258 impl<'a, 'b> MacroExpander<'a, 'b> {
 259     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 260         MacroExpander { cx: cx, monotonic: monotonic }
 261     }
 262
 263     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 264         let mut module = ModuleData {
 265             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 266             directory: match self.cx.source_map().span_to_unmapped_path(krate.span) {
 267                 FileName::Real(path) => path,
 268                 other => PathBuf::from(other.to_string()),
 269             },
 270         };
 271         module.directory.pop();
 272         self.cx.root_path = module.directory.clone();
 273         self.cx.current_expansion.module = Rc::new(module);
 274         self.cx.current_expansion.crate_span = Some(krate.span);
 275
 276         let orig_mod_span = krate.module.inner;
 277
 278         let krate_item = AstFragment::Items(smallvec![P(ast::Item {
 279             attrs: krate.attrs,
 280             span: krate.span,
 281             node: ast::ItemKind::Mod(krate.module),
 282             ident: keywords::Invalid.ident(),
 283             id: ast::DUMMY_NODE_ID,
 284             vis: respan(krate.span.shrink_to_lo(), ast::VisibilityKind::Public),
 285             tokens: None,
 286         })]);
 287
 288         match self.expand_fragment(krate_item).make_items().pop().map(P::into_inner) {
 289             Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
 290                 krate.attrs = attrs;
 291                 krate.module = module;
 292             },
 293             None => {
 294                 // Resolution failed so we return an empty expansion
 295                 krate.attrs = vec![];
 296                 krate.module = ast::Mod {
 297                     inner: orig_mod_span,
 298                     items: vec![],
 299                     inline: true,
 300                 };
 301             },
 302             _ => unreachable!(),
 303         };
 304         self.cx.trace_macros_diag();
 305         krate
 306     }
 307
 308     // Fully expand all macro invocations in this AST fragment.
 309     fn expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragment {
 310         let orig_expansion_data = self.cx.current_expansion.clone();
 311         self.cx.current_expansion.depth = 0;
 312
 313         // Collect all macro invocations and replace them with placeholders.
 314         let (fragment_with_placeholders, mut invocations)
 315             = self.collect_invocations(input_fragment, &[]);
 316
 317         // Optimization: if we resolve all imports now,
 318         // we'll be able to immediately resolve most of imported macros.
 319         self.resolve_imports();
 320
 321         // Resolve paths in all invocations and produce output expanded fragments for them, but
 322         // do not insert them into our input AST fragment yet, only store in `expanded_fragments`.
 323         // The output fragments also go through expansion recursively until no invocations are left.
 324         // Unresolved macros produce dummy outputs as a recovery measure.
 325         invocations.reverse();
 326         let mut expanded_fragments = Vec::new();
 327         let mut derives: FxHashMap<Mark, Vec<_>> = FxHashMap::default();
 328         let mut undetermined_invocations = Vec::new();
 329         let (mut progress, mut force) = (false, !self.monotonic);
 330         loop {
 331             let invoc = if let Some(invoc) = invocations.pop() {
 332                 invoc
 333             } else {
 334                 self.resolve_imports();
 335                 if undetermined_invocations.is_empty() { break }
 336                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 337                 force = !mem::replace(&mut progress, false);
 338                 continue
 339             };
 340
 341             let scope =
 342                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 343             let ext = match self.cx.resolver.resolve_macro_invocation(&invoc, scope, force) {
 344                 Ok(ext) => Some(ext),
 345                 Err(Determinacy::Determined) => None,
 346                 Err(Determinacy::Undetermined) => {
 347                     undetermined_invocations.push(invoc);
 348                     continue
 349                 }
 350             };
 351
 352             progress = true;
 353             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
 354             self.cx.current_expansion = invoc.expansion_data.clone();
 355
 356             self.cx.current_expansion.mark = scope;
 357             // FIXME(jseyfried): Refactor out the following logic
 358             let (expanded_fragment, new_invocations) = if let Some(ext) = ext {
 359                 if let Some(ext) = ext {
 360                     let dummy = invoc.fragment_kind.dummy(invoc.span()).unwrap();
 361                     let fragment = self.expand_invoc(invoc, &*ext).unwrap_or(dummy);
 362                     self.collect_invocations(fragment, &[])
 363                 } else if let InvocationKind::Attr { attr: None, traits, item, .. } = invoc.kind {
 364                     if !item.derive_allowed() {
 365                         let attr = attr::find_by_name(item.attrs(), "derive")
 366                             .expect("`derive` attribute should exist");
 367                         let span = attr.span;
 368                         let mut err = self.cx.mut_span_err(span,
 369                                                            "`derive` may only be applied to \
 370                                                             structs, enums and unions");
 371                         if let ast::AttrStyle::Inner = attr.style {
 372                             let trait_list = traits.iter()
 373                                 .map(|t| t.to_string()).collect::<Vec<_>>();
 374                             let suggestion = format!("#[derive({})]", trait_list.join(", "));
 375                             err.span_suggestion_with_applicability(
 376                                 span, "try an outer attribute", suggestion,
 377                                 // We don't 𝑘𝑛𝑜𝑤 that the following item is an ADT
 378                                 Applicability::MaybeIncorrect
 379                             );
 380                         }
 381                         err.emit();
 382                     }
 383
 384                     let item = self.fully_configure(item)
 385                         .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
 386                     let item_with_markers =
 387                         add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
 388                     let derives = derives.entry(invoc.expansion_data.mark).or_default();
 389
 390                     for path in &traits {
 391                         let mark = Mark::fresh(self.cx.current_expansion.mark);
 392                         derives.push(mark);
 393                         let item = match self.cx.resolver.resolve_macro_path(
 394                                 path, MacroKind::Derive, Mark::root(), Vec::new(), false) {
 395                             Ok(ext) => match *ext {
 396                                 BuiltinDerive(..) => item_with_markers.clone(),
 397                                 _ => item.clone(),
 398                             },
 399                             _ => item.clone(),
 400                         };
 401                         invocations.push(Invocation {
 402                             kind: InvocationKind::Derive { path: path.clone(), item: item },
 403                             fragment_kind: invoc.fragment_kind,
 404                             expansion_data: ExpansionData {
 405                                 mark,
 406                                 ..invoc.expansion_data.clone()
 407                             },
 408                         });
 409                     }
 410                     let fragment = invoc.fragment_kind
 411                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 412                     self.collect_invocations(fragment, derives)
 413                 } else {
 414                     unreachable!()
 415                 }
 416             } else {
 417                 self.collect_invocations(invoc.fragment_kind.dummy(invoc.span()).unwrap(), &[])
 418             };
 419
 420             if expanded_fragments.len() < depth {
 421                 expanded_fragments.push(Vec::new());
 422             }
 423             expanded_fragments[depth - 1].push((mark, expanded_fragment));
 424             if !self.cx.ecfg.single_step {
 425                 invocations.extend(new_invocations.into_iter().rev());
 426             }
 427         }
 428
 429         self.cx.current_expansion = orig_expansion_data;
 430
 431         // Finally incorporate all the expanded macros into the input AST fragment.
 432         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 433         while let Some(expanded_fragments) = expanded_fragments.pop() {
 434             for (mark, expanded_fragment) in expanded_fragments.into_iter().rev() {
 435                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 436                 placeholder_expander.add(NodeId::placeholder_from_mark(mark),
 437                                          expanded_fragment, derives);
 438             }
 439         }
 440         fragment_with_placeholders.fold_with(&mut placeholder_expander)
 441     }
 442
 443     fn resolve_imports(&mut self) {
 444         if self.monotonic {
 445             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 446             self.cx.resolver.resolve_imports();
 447             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 448         }
 449     }
 450
 451     /// Collect all macro invocations reachable at this time in this AST fragment, and replace
 452     /// them with "placeholders" - dummy macro invocations with specially crafted `NodeId`s.
 453     /// Then call into resolver that builds a skeleton ("reduced graph") of the fragment and
 454     /// prepares data for resolving paths of macro invocations.
 455     fn collect_invocations(&mut self, fragment: AstFragment, derives: &[Mark])
 456                            -> (AstFragment, Vec<Invocation>) {
 457         let (fragment_with_placeholders, invocations) = {
 458             let mut collector = InvocationCollector {
 459                 cfg: StripUnconfigured {
 460                     sess: self.cx.parse_sess,
 461                     features: self.cx.ecfg.features,
 462                 },
 463                 cx: self.cx,
 464                 invocations: Vec::new(),
 465                 monotonic: self.monotonic,
 466             };
 467             (fragment.fold_with(&mut collector), collector.invocations)
 468         };
 469
 470         if self.monotonic {
 471             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 472             let mark = self.cx.current_expansion.mark;
 473             self.cx.resolver.visit_ast_fragment_with_placeholders(mark, &fragment_with_placeholders,
 474                                                                   derives);
 475             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 476         }
 477
 478         (fragment_with_placeholders, invocations)
 479     }
 480
 481     fn fully_configure(&mut self, item: Annotatable) -> Annotatable {
 482         let mut cfg = StripUnconfigured {
 483             sess: self.cx.parse_sess,
 484             features: self.cx.ecfg.features,
 485         };
 486         // Since the item itself has already been configured by the InvocationCollector,
 487         // we know that fold result vector will contain exactly one element
 488         match item {
 489             Annotatable::Item(item) => {
 490                 Annotatable::Item(cfg.fold_item(item).pop().unwrap())
 491             }
 492             Annotatable::TraitItem(item) => {
 493                 Annotatable::TraitItem(item.map(|item| cfg.fold_trait_item(item).pop().unwrap()))
 494             }
 495             Annotatable::ImplItem(item) => {
 496                 Annotatable::ImplItem(item.map(|item| cfg.fold_impl_item(item).pop().unwrap()))
 497             }
 498             Annotatable::ForeignItem(item) => {
 499                 Annotatable::ForeignItem(
 500                     item.map(|item| cfg.fold_foreign_item(item).pop().unwrap())
 501                 )
 502             }
 503             Annotatable::Stmt(stmt) => {
 504                 Annotatable::Stmt(stmt.map(|stmt| cfg.fold_stmt(stmt).pop().unwrap()))
 505             }
 506             Annotatable::Expr(expr) => {
 507                 Annotatable::Expr(cfg.fold_expr(expr))
 508             }
 509         }
 510     }
 511
 512     fn expand_invoc(&mut self, invoc: Invocation, ext: &SyntaxExtension) -> Option<AstFragment> {
 513         if invoc.fragment_kind == AstFragmentKind::ForeignItems &&
 514            !self.cx.ecfg.macros_in_extern_enabled() {
 515             if let SyntaxExtension::NonMacroAttr { .. } = *ext {} else {
 516                 emit_feature_err(&self.cx.parse_sess, "macros_in_extern",
 517                                  invoc.span(), GateIssue::Language,
 518                                  "macro invocations in `extern {}` blocks are experimental");
 519             }
 520         }
 521
 522         let result = match invoc.kind {
 523             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext)?,
 524             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext)?,
 525             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext)?,
 526         };
 527
 528         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
 529             let info = self.cx.current_expansion.mark.expn_info().unwrap();
 530             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
 531             let mut err = self.cx.struct_span_err(info.call_site,
 532                 &format!("recursion limit reached while expanding the macro `{}`",
 533                          info.format.name()));
 534             err.help(&format!(
 535                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
 536                 suggested_limit));
 537             err.emit();
 538             self.cx.trace_macros_diag();
 539             FatalError.raise();
 540         }
 541
 542         Some(result)
 543     }
 544
 545     fn expand_attr_invoc(&mut self,
 546                          invoc: Invocation,
 547                          ext: &SyntaxExtension)
 548                          -> Option<AstFragment> {
 549         let (attr, item) = match invoc.kind {
 550             InvocationKind::Attr { attr, item, .. } => (attr?, item),
 551             _ => unreachable!(),
 552         };
 553
 554         if let NonMacroAttr { mark_used: false } = *ext {} else {
 555             // Macro attrs are always used when expanded,
 556             // non-macro attrs are considered used when the field says so.
 557             attr::mark_used(&attr);
 558         }
 559         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 560             call_site: attr.span,
 561             def_site: None,
 562             format: MacroAttribute(Symbol::intern(&attr.path.to_string())),
 563             allow_internal_unstable: false,
 564             allow_internal_unsafe: false,
 565             local_inner_macros: false,
 566             edition: ext.edition(),
 567         });
 568
 569         match *ext {
 570             NonMacroAttr { .. } => {
 571                 attr::mark_known(&attr);
 572                 let item = item.map_attrs(|mut attrs| { attrs.push(attr); attrs });
 573                 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
 574             }
 575             MultiModifier(ref mac) => {
 576                 let meta = attr.parse_meta(self.cx.parse_sess)
 577                                .map_err(|mut e| { e.emit(); }).ok()?;
 578                 let item = mac.expand(self.cx, attr.span, &meta, item);
 579                 Some(invoc.fragment_kind.expect_from_annotatables(item))
 580             }
 581             MultiDecorator(ref mac) => {
 582                 let mut items = Vec::new();
 583                 let meta = attr.parse_meta(self.cx.parse_sess)
 584                                .expect("derive meta should already have been parsed");
 585                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 586                 items.push(item);
 587                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 588             }
 589             AttrProcMacro(ref mac, ..) => {
 590                 self.gate_proc_macro_attr_item(attr.span, &item);
 591                 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
 592                     Annotatable::Item(item) => token::NtItem(item),
 593                     Annotatable::TraitItem(item) => token::NtTraitItem(item.into_inner()),
 594                     Annotatable::ImplItem(item) => token::NtImplItem(item.into_inner()),
 595                     Annotatable::ForeignItem(item) => token::NtForeignItem(item.into_inner()),
 596                     Annotatable::Stmt(stmt) => token::NtStmt(stmt.into_inner()),
 597                     Annotatable::Expr(expr) => token::NtExpr(expr),
 598                 })).into();
 599                 let input = self.extract_proc_macro_attr_input(attr.tokens, attr.span);
 600                 let tok_result = mac.expand(self.cx, attr.span, input, item_tok);
 601                 let res = self.parse_ast_fragment(tok_result, invoc.fragment_kind,
 602                                                   &attr.path, attr.span);
 603                 self.gate_proc_macro_expansion(attr.span, &res);
 604                 res
 605             }
 606             ProcMacroDerive(..) | BuiltinDerive(..) => {
 607                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 608                 self.cx.trace_macros_diag();
 609                 invoc.fragment_kind.dummy(attr.span)
 610             }
 611             _ => {
 612                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 613                 self.cx.span_err(attr.span, msg);
 614                 self.cx.trace_macros_diag();
 615                 invoc.fragment_kind.dummy(attr.span)
 616             }
 617         }
 618     }
 619
 620     fn extract_proc_macro_attr_input(&self, tokens: TokenStream, span: Span) -> TokenStream {
 621         let mut trees = tokens.trees();
 622         match trees.next() {
 623             Some(TokenTree::Delimited(_, delim)) => {
 624                 if trees.next().is_none() {
 625                     return delim.tts.into()
 626                 }
 627             }
 628             Some(TokenTree::Token(..)) => {}
 629             None => return TokenStream::empty(),
 630         }
 631         self.cx.span_err(span, "custom attribute invocations must be \
 632             of the form #[foo] or #[foo(..)], the macro name must only be \
 633             followed by a delimiter token");
 634         TokenStream::empty()
 635     }
 636
 637     fn gate_proc_macro_attr_item(&self, span: Span, item: &Annotatable) {
 638         let (kind, gate) = match *item {
 639             Annotatable::Item(ref item) => {
 640                 match item.node {
 641                     ItemKind::Mod(_) if self.cx.ecfg.proc_macro_hygiene() => return,
 642                     ItemKind::Mod(_) => ("modules", "proc_macro_hygiene"),
 643                     _ => return,
 644                 }
 645             }
 646             Annotatable::TraitItem(_) => return,
 647             Annotatable::ImplItem(_) => return,
 648             Annotatable::ForeignItem(_) => return,
 649             Annotatable::Stmt(_) |
 650             Annotatable::Expr(_) if self.cx.ecfg.proc_macro_hygiene() => return,
 651             Annotatable::Stmt(_) => ("statements", "proc_macro_hygiene"),
 652             Annotatable::Expr(_) => ("expressions", "proc_macro_hygiene"),
 653         };
 654         emit_feature_err(
 655             self.cx.parse_sess,
 656             gate,
 657             span,
 658             GateIssue::Language,
 659             &format!("custom attributes cannot be applied to {}", kind),
 660         );
 661     }
 662
 663     fn gate_proc_macro_expansion(&self, span: Span, fragment: &Option<AstFragment>) {
 664         if self.cx.ecfg.proc_macro_hygiene() {
 665             return
 666         }
 667         let fragment = match fragment {
 668             Some(fragment) => fragment,
 669             None => return,
 670         };
 671
 672         fragment.visit_with(&mut DisallowMacros {
 673             span,
 674             parse_sess: self.cx.parse_sess,
 675         });
 676
 677         struct DisallowMacros<'a> {
 678             span: Span,
 679             parse_sess: &'a ParseSess,
 680         }
 681
 682         impl<'ast, 'a> Visitor<'ast> for DisallowMacros<'a> {
 683             fn visit_item(&mut self, i: &'ast ast::Item) {
 684                 if let ast::ItemKind::MacroDef(_) = i.node {
 685                     emit_feature_err(
 686                         self.parse_sess,
 687                         "proc_macro_hygiene",
 688                         self.span,
 689                         GateIssue::Language,
 690                         &format!("procedural macros cannot expand to macro definitions"),
 691                     );
 692                 }
 693                 visit::walk_item(self, i);
 694             }
 695
 696             fn visit_mac(&mut self, _mac: &'ast ast::Mac) {
 697                 // ...
 698             }
 699         }
 700     }
 701
 702     /// Expand a macro invocation. Returns the resulting expanded AST fragment.
 703     fn expand_bang_invoc(&mut self,
 704                          invoc: Invocation,
 705                          ext: &SyntaxExtension)
 706                          -> Option<AstFragment> {
 707         let (mark, kind) = (invoc.expansion_data.mark, invoc.fragment_kind);
 708         let (mac, ident, span) = match invoc.kind {
 709             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 710             _ => unreachable!(),
 711         };
 712         let path = &mac.node.path;
 713
 714         let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
 715         let validate_and_set_expn_info = |this: &mut Self, // arg instead of capture
 716                                           def_site_span: Option<Span>,
 717                                           allow_internal_unstable,
 718                                           allow_internal_unsafe,
 719                                           local_inner_macros,
 720                                           // can't infer this type
 721                                           unstable_feature: Option<(Symbol, u32)>,
 722                                           edition| {
 723
 724             // feature-gate the macro invocation
 725             if let Some((feature, issue)) = unstable_feature {
 726                 let crate_span = this.cx.current_expansion.crate_span.unwrap();
 727                 // don't stability-check macros in the same crate
 728                 // (the only time this is null is for syntax extensions registered as macros)
 729                 if def_site_span.map_or(false, |def_span| !crate_span.contains(def_span))
 730                     && !span.allows_unstable() && this.cx.ecfg.features.map_or(true, |feats| {
 731                     // macro features will count as lib features
 732                     !feats.declared_lib_features.iter().any(|&(feat, _)| feat == feature)
 733                 }) {
 734                     let explain = format!("macro {}! is unstable", path);
 735                     emit_feature_err(this.cx.parse_sess, &*feature.as_str(), span,
 736                                      GateIssue::Library(Some(issue)), &explain);
 737                     this.cx.trace_macros_diag();
 738                     return Err(kind.dummy(span));
 739                 }
 740             }
 741
 742             if ident.name != keywords::Invalid.name() {
 743                 let msg = format!("macro {}! expects no ident argument, given '{}'", path, ident);
 744                 this.cx.span_err(path.span, &msg);
 745                 this.cx.trace_macros_diag();
 746                 return Err(kind.dummy(span));
 747             }
 748             mark.set_expn_info(ExpnInfo {
 749                 call_site: span,
 750                 def_site: def_site_span,
 751                 format: macro_bang_format(path),
 752                 allow_internal_unstable,
 753                 allow_internal_unsafe,
 754                 local_inner_macros,
 755                 edition,
 756             });
 757             Ok(())
 758         };
 759
 760         let opt_expanded = match *ext {
 761             DeclMacro { ref expander, def_info, edition, .. } => {
 762                 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
 763                                                                     false, false, false, None,
 764                                                                     edition) {
 765                     dummy_span
 766                 } else {
 767                     kind.make_from(expander.expand(self.cx, span, mac.node.stream(), None))
 768                 }
 769             }
 770
 771             NormalTT {
 772                 ref expander,
 773                 def_info,
 774                 allow_internal_unstable,
 775                 allow_internal_unsafe,
 776                 local_inner_macros,
 777                 unstable_feature,
 778                 edition,
 779             } => {
 780                 if let Err(dummy_span) = validate_and_set_expn_info(self, def_info.map(|(_, s)| s),
 781                                                                     allow_internal_unstable,
 782                                                                     allow_internal_unsafe,
 783                                                                     local_inner_macros,
 784                                                                     unstable_feature,
 785                                                                     edition) {
 786                     dummy_span
 787                 } else {
 788                     kind.make_from(expander.expand(
 789                         self.cx,
 790                         span,
 791                         mac.node.stream(),
 792                         def_info.map(|(_, s)| s),
 793                     ))
 794                 }
 795             }
 796
 797             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 798                 if ident.name == keywords::Invalid.name() {
 799                     self.cx.span_err(path.span,
 800                                     &format!("macro {}! expects an ident argument", path));
 801                     self.cx.trace_macros_diag();
 802                     kind.dummy(span)
 803                 } else {
 804                     invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 805                         call_site: span,
 806                         def_site: tt_span,
 807                         format: macro_bang_format(path),
 808                         allow_internal_unstable,
 809                         allow_internal_unsafe: false,
 810                         local_inner_macros: false,
 811                         edition: hygiene::default_edition(),
 812                     });
 813
 814                     let input: Vec<_> = mac.node.stream().into_trees().collect();
 815                     kind.make_from(expander.expand(self.cx, span, ident, input))
 816                 }
 817             }
 818
 819             MultiDecorator(..) | MultiModifier(..) |
 820             AttrProcMacro(..) | SyntaxExtension::NonMacroAttr { .. } => {
 821                 self.cx.span_err(path.span,
 822                                  &format!("`{}` can only be used in attributes", path));
 823                 self.cx.trace_macros_diag();
 824                 kind.dummy(span)
 825             }
 826
 827             ProcMacroDerive(..) | BuiltinDerive(..) => {
 828                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 829                 self.cx.trace_macros_diag();
 830                 kind.dummy(span)
 831             }
 832
 833             SyntaxExtension::ProcMacro { ref expander, allow_internal_unstable, edition } => {
 834                 if ident.name != keywords::Invalid.name() {
 835                     let msg =
 836                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 837                     self.cx.span_err(path.span, &msg);
 838                     self.cx.trace_macros_diag();
 839                     kind.dummy(span)
 840                 } else {
 841                     self.gate_proc_macro_expansion_kind(span, kind);
 842                     invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 843                         call_site: span,
 844                         // FIXME procedural macros do not have proper span info
 845                         // yet, when they do, we should use it here.
 846                         def_site: None,
 847                         format: macro_bang_format(path),
 848                         // FIXME probably want to follow macro_rules macros here.
 849                         allow_internal_unstable,
 850                         allow_internal_unsafe: false,
 851                         local_inner_macros: false,
 852                         edition,
 853                     });
 854
 855                     let tok_result = expander.expand(self.cx, span, mac.node.stream());
 856                     let result = self.parse_ast_fragment(tok_result, kind, path, span);
 857                     self.gate_proc_macro_expansion(span, &result);
 858                     result
 859                 }
 860             }
 861         };
 862
 863         if opt_expanded.is_some() {
 864             opt_expanded
 865         } else {
 866             let msg = format!("non-{kind} macro in {kind} position: {name}",
 867                               name = path.segments[0].ident.name, kind = kind.name());
 868             self.cx.span_err(path.span, &msg);
 869             self.cx.trace_macros_diag();
 870             kind.dummy(span)
 871         }
 872     }
 873
 874     fn gate_proc_macro_expansion_kind(&self, span: Span, kind: AstFragmentKind) {
 875         let kind = match kind {
 876             AstFragmentKind::Expr => "expressions",
 877             AstFragmentKind::OptExpr => "expressions",
 878             AstFragmentKind::Pat => "patterns",
 879             AstFragmentKind::Ty => "types",
 880             AstFragmentKind::Stmts => "statements",
 881             AstFragmentKind::Items => return,
 882             AstFragmentKind::TraitItems => return,
 883             AstFragmentKind::ImplItems => return,
 884             AstFragmentKind::ForeignItems => return,
 885         };
 886         if self.cx.ecfg.proc_macro_hygiene() {
 887             return
 888         }
 889         emit_feature_err(
 890             self.cx.parse_sess,
 891             "proc_macro_hygiene",
 892             span,
 893             GateIssue::Language,
 894             &format!("procedural macros cannot be expanded to {}", kind),
 895         );
 896     }
 897
 898     /// Expand a derive invocation. Returns the resulting expanded AST fragment.
 899     fn expand_derive_invoc(&mut self,
 900                            invoc: Invocation,
 901                            ext: &SyntaxExtension)
 902                            -> Option<AstFragment> {
 903         let (path, item) = match invoc.kind {
 904             InvocationKind::Derive { path, item } => (path, item),
 905             _ => unreachable!(),
 906         };
 907         if !item.derive_allowed() {
 908             return None;
 909         }
 910
 911         let pretty_name = Symbol::intern(&format!("derive({})", path));
 912         let span = path.span;
 913         let attr = ast::Attribute {
 914             path, span,
 915             tokens: TokenStream::empty(),
 916             // irrelevant:
 917             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 918         };
 919
 920         let mut expn_info = ExpnInfo {
 921             call_site: span,
 922             def_site: None,
 923             format: MacroAttribute(pretty_name),
 924             allow_internal_unstable: false,
 925             allow_internal_unsafe: false,
 926             local_inner_macros: false,
 927             edition: ext.edition(),
 928         };
 929
 930         match *ext {
 931             ProcMacroDerive(ref ext, ..) => {
 932                 invoc.expansion_data.mark.set_expn_info(expn_info);
 933                 let span = span.with_ctxt(self.cx.backtrace());
 934                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 935                     ident: Path::from_ident(keywords::Invalid.ident()),
 936                     span: DUMMY_SP,
 937                     node: ast::MetaItemKind::Word,
 938                 };
 939                 let items = ext.expand(self.cx, span, &dummy, item);
 940                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 941             }
 942             BuiltinDerive(func) => {
 943                 expn_info.allow_internal_unstable = true;
 944                 invoc.expansion_data.mark.set_expn_info(expn_info);
 945                 let span = span.with_ctxt(self.cx.backtrace());
 946                 let mut items = Vec::new();
 947                 func(self.cx, span, &attr.meta()?, &item, &mut |a| items.push(a));
 948                 Some(invoc.fragment_kind.expect_from_annotatables(items))
 949             }
 950             _ => {
 951                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 952                 self.cx.span_err(span, msg);
 953                 self.cx.trace_macros_diag();
 954                 invoc.fragment_kind.dummy(span)
 955             }
 956         }
 957     }
 958
 959     fn parse_ast_fragment(&mut self,
 960                           toks: TokenStream,
 961                           kind: AstFragmentKind,
 962                           path: &Path,
 963                           span: Span)
 964                           -> Option<AstFragment> {
 965         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 966         match parser.parse_ast_fragment(kind, false) {
 967             Ok(fragment) => {
 968                 parser.ensure_complete_parse(path, kind.name(), span);
 969                 Some(fragment)
 970             }
 971             Err(mut err) => {
 972                 err.set_span(span);
 973                 err.emit();
 974                 self.cx.trace_macros_diag();
 975                 kind.dummy(span)
 976             }
 977         }
 978     }
 979 }
 980
 981 impl<'a> Parser<'a> {
 982     pub fn parse_ast_fragment(&mut self, kind: AstFragmentKind, macro_legacy_warnings: bool)
 983                               -> PResult<'a, AstFragment> {
 984         Ok(match kind {
 985             AstFragmentKind::Items => {
 986                 let mut items = SmallVec::new();
 987                 while let Some(item) = self.parse_item()? {
 988                     items.push(item);
 989                 }
 990                 AstFragment::Items(items)
 991             }
 992             AstFragmentKind::TraitItems => {
 993                 let mut items = SmallVec::new();
 994                 while self.token != token::Eof {
 995                     items.push(self.parse_trait_item(&mut false)?);
 996                 }
 997                 AstFragment::TraitItems(items)
 998             }
 999             AstFragmentKind::ImplItems => {
1000                 let mut items = SmallVec::new();
1001                 while self.token != token::Eof {
1002                     items.push(self.parse_impl_item(&mut false)?);
1003                 }
1004                 AstFragment::ImplItems(items)
1005             }
1006             AstFragmentKind::ForeignItems => {
1007                 let mut items = SmallVec::new();
1008                 while self.token != token::Eof {
1009                     items.push(self.parse_foreign_item()?);
1010                 }
1011                 AstFragment::ForeignItems(items)
1012             }
1013             AstFragmentKind::Stmts => {
1014                 let mut stmts = SmallVec::new();
1015                 while self.token != token::Eof &&
1016                       // won't make progress on a `}`
1017                       self.token != token::CloseDelim(token::Brace) {
1018                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
1019                         stmts.push(stmt);
1020                     }
1021                 }
1022                 AstFragment::Stmts(stmts)
1023             }
1024             AstFragmentKind::Expr => AstFragment::Expr(self.parse_expr()?),
1025             AstFragmentKind::OptExpr => {
1026                 if self.token != token::Eof {
1027                     AstFragment::OptExpr(Some(self.parse_expr()?))
1028                 } else {
1029                     AstFragment::OptExpr(None)
1030                 }
1031             },
1032             AstFragmentKind::Ty => AstFragment::Ty(self.parse_ty()?),
1033             AstFragmentKind::Pat => AstFragment::Pat(self.parse_pat(None)?),
1034         })
1035     }
1036
1037     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
1038         if self.token != token::Eof {
1039             let msg = format!("macro expansion ignores token `{}` and any following",
1040                               self.this_token_to_string());
1041             // Avoid emitting backtrace info twice.
1042             let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
1043             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
1044             err.span_label(span, "caused by the macro expansion here");
1045             let msg = format!(
1046                 "the usage of `{}!` is likely invalid in {} context",
1047                 macro_path,
1048                 kind_name,
1049             );
1050             err.note(&msg);
1051             let semi_span = self.sess.source_map().next_point(span);
1052
1053             let semi_full_span = semi_span.to(self.sess.source_map().next_point(semi_span));
1054             match self.sess.source_map().span_to_snippet(semi_full_span) {
1055                 Ok(ref snippet) if &snippet[..] != ";" && kind_name == "expression" => {
1056                     err.span_suggestion_with_applicability(
1057                         semi_span,
1058                         "you might be missing a semicolon here",
1059                         ";".to_owned(),
1060                         Applicability::MaybeIncorrect,
1061                     );
1062                 }
1063                 _ => {}
1064             }
1065             err.emit();
1066         }
1067     }
1068 }
1069
1070 struct InvocationCollector<'a, 'b: 'a> {
1071     cx: &'a mut ExtCtxt<'b>,
1072     cfg: StripUnconfigured<'a>,
1073     invocations: Vec<Invocation>,
1074     monotonic: bool,
1075 }
1076
1077 impl<'a, 'b> InvocationCollector<'a, 'b> {
1078     fn collect(&mut self, fragment_kind: AstFragmentKind, kind: InvocationKind) -> AstFragment {
1079         let mark = Mark::fresh(self.cx.current_expansion.mark);
1080         self.invocations.push(Invocation {
1081             kind,
1082             fragment_kind,
1083             expansion_data: ExpansionData {
1084                 mark,
1085                 depth: self.cx.current_expansion.depth + 1,
1086                 ..self.cx.current_expansion.clone()
1087             },
1088         });
1089         placeholder(fragment_kind, NodeId::placeholder_from_mark(mark))
1090     }
1091
1092     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: AstFragmentKind) -> AstFragment {
1093         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
1094     }
1095
1096     fn collect_attr(&mut self,
1097                     attr: Option<ast::Attribute>,
1098                     traits: Vec<Path>,
1099                     item: Annotatable,
1100                     kind: AstFragmentKind,
1101                     after_derive: bool)
1102                     -> AstFragment {
1103         self.collect(kind, InvocationKind::Attr { attr, traits, item, after_derive })
1104     }
1105
1106     fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, after_derive: &mut bool)
1107                        -> Option<ast::Attribute> {
1108         let attr = attrs.iter()
1109                         .position(|a| {
1110                             if a.path == "derive" {
1111                                 *after_derive = true;
1112                             }
1113                             !attr::is_known(a) && !is_builtin_attr(a)
1114                         })
1115                         .map(|i| attrs.remove(i));
1116         if let Some(attr) = &attr {
1117             if !self.cx.ecfg.enable_custom_inner_attributes() &&
1118                attr.style == ast::AttrStyle::Inner && attr.path != "test" {
1119                 emit_feature_err(&self.cx.parse_sess, "custom_inner_attributes",
1120                                  attr.span, GateIssue::Language,
1121                                  "non-builtin inner attributes are unstable");
1122             }
1123         }
1124         attr
1125     }
1126
1127     /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
1128     fn classify_item<T>(&mut self, mut item: T)
1129                         -> (Option<ast::Attribute>, Vec<Path>, T, /* after_derive */ bool)
1130         where T: HasAttrs,
1131     {
1132         let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
1133
1134         item = item.map_attrs(|mut attrs| {
1135             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
1136                                                                                      true) {
1137                 attr = Some(legacy_attr_invoc);
1138                 return attrs;
1139             }
1140
1141             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1142             traits = collect_derives(&mut self.cx, &mut attrs);
1143             attrs
1144         });
1145
1146         (attr, traits, item, after_derive)
1147     }
1148
1149     /// Alternative of `classify_item()` that ignores `#[derive]` so invocations fallthrough
1150     /// to the unused-attributes lint (making it an error on statements and expressions
1151     /// is a breaking change)
1152     fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T)
1153                                      -> (Option<ast::Attribute>, T, /* after_derive */ bool) {
1154         let (mut attr, mut after_derive) = (None, false);
1155
1156         item = item.map_attrs(|mut attrs| {
1157             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
1158                                                                                      false) {
1159                 attr = Some(legacy_attr_invoc);
1160                 return attrs;
1161             }
1162
1163             attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
1164             attrs
1165         });
1166
1167         (attr, item, after_derive)
1168     }
1169
1170     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
1171         self.cfg.configure(node)
1172     }
1173
1174     // Detect use of feature-gated or invalid attributes on macro invocations
1175     // since they will not be detected after macro expansion.
1176     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
1177         let features = self.cx.ecfg.features.unwrap();
1178         for attr in attrs.iter() {
1179             self.check_attribute_inner(attr, features);
1180
1181             // macros are expanded before any lint passes so this warning has to be hardcoded
1182             if attr.path == "derive" {
1183                 self.cx.struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
1184                     .note("this may become a hard error in a future release")
1185                     .emit();
1186             }
1187         }
1188     }
1189
1190     fn check_attribute(&mut self, at: &ast::Attribute) {
1191         let features = self.cx.ecfg.features.unwrap();
1192         self.check_attribute_inner(at, features);
1193     }
1194
1195     fn check_attribute_inner(&mut self, at: &ast::Attribute, features: &Features) {
1196         feature_gate::check_attribute(at, self.cx.parse_sess, features);
1197     }
1198 }
1199
1200 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
1201     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
1202         let mut expr = self.cfg.configure_expr(expr).into_inner();
1203         expr.node = self.cfg.configure_expr_kind(expr.node);
1204
1205         // ignore derives so they remain unused
1206         let (attr, expr, after_derive) = self.classify_nonitem(expr);
1207
1208         if attr.is_some() {
1209             // collect the invoc regardless of whether or not attributes are permitted here
1210             // expansion will eat the attribute so it won't error later
1211             attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1212
1213             // AstFragmentKind::Expr requires the macro to emit an expression
1214             return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1215                                      AstFragmentKind::Expr, after_derive).make_expr();
1216         }
1217
1218         if let ast::ExprKind::Mac(mac) = expr.node {
1219             self.check_attributes(&expr.attrs);
1220             self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr()
1221         } else {
1222             P(noop_fold_expr(expr, self))
1223         }
1224     }
1225
1226     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
1227         let mut expr = configure!(self, expr).into_inner();
1228         expr.node = self.cfg.configure_expr_kind(expr.node);
1229
1230         // ignore derives so they remain unused
1231         let (attr, expr, after_derive) = self.classify_nonitem(expr);
1232
1233         if attr.is_some() {
1234             attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
1235
1236             return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
1237                                      AstFragmentKind::OptExpr, after_derive).make_opt_expr();
1238         }
1239
1240         if let ast::ExprKind::Mac(mac) = expr.node {
1241             self.check_attributes(&expr.attrs);
1242             self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr).make_opt_expr()
1243         } else {
1244             Some(P(noop_fold_expr(expr, self)))
1245         }
1246     }
1247
1248     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
1249         let pat = self.cfg.configure_pat(pat);
1250         match pat.node {
1251             PatKind::Mac(_) => {}
1252             _ => return noop_fold_pat(pat, self),
1253         }
1254
1255         pat.and_then(|pat| match pat.node {
1256             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat(),
1257             _ => unreachable!(),
1258         })
1259     }
1260
1261     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVec<[ast::Stmt; 1]> {
1262         let mut stmt = match self.cfg.configure_stmt(stmt) {
1263             Some(stmt) => stmt,
1264             None => return SmallVec::new(),
1265         };
1266
1267         // we'll expand attributes on expressions separately
1268         if !stmt.is_expr() {
1269             let (attr, derives, stmt_, after_derive) = if stmt.is_item() {
1270                 self.classify_item(stmt)
1271             } else {
1272                 // ignore derives on non-item statements so it falls through
1273                 // to the unused-attributes lint
1274                 let (attr, stmt, after_derive) = self.classify_nonitem(stmt);
1275                 (attr, vec![], stmt, after_derive)
1276             };
1277
1278             if attr.is_some() || !derives.is_empty() {
1279                 return self.collect_attr(attr, derives, Annotatable::Stmt(P(stmt_)),
1280                                          AstFragmentKind::Stmts, after_derive).make_stmts();
1281             }
1282
1283             stmt = stmt_;
1284         }
1285
1286         if let StmtKind::Mac(mac) = stmt.node {
1287             let (mac, style, attrs) = mac.into_inner();
1288             self.check_attributes(&attrs);
1289             let mut placeholder = self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts)
1290                                         .make_stmts();
1291
1292             // If this is a macro invocation with a semicolon, then apply that
1293             // semicolon to the final statement produced by expansion.
1294             if style == MacStmtStyle::Semicolon {
1295                 if let Some(stmt) = placeholder.pop() {
1296                     placeholder.push(stmt.add_trailing_semicolon());
1297                 }
1298             }
1299
1300             return placeholder;
1301         }
1302
1303         // The placeholder expander gives ids to statements, so we avoid folding the id here.
1304         let ast::Stmt { id, node, span } = stmt;
1305         noop_fold_stmt_kind(node, self).into_iter().map(|node| {
1306             ast::Stmt { id, node, span }
1307         }).collect()
1308
1309     }
1310
1311     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
1312         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
1313         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
1314         let result = noop_fold_block(block, self);
1315         self.cx.current_expansion.directory_ownership = old_directory_ownership;
1316         result
1317     }
1318
1319     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
1320         let item = configure!(self, item);
1321
1322         let (attr, traits, item, after_derive) = self.classify_item(item);
1323         if attr.is_some() || !traits.is_empty() {
1324             return self.collect_attr(attr, traits, Annotatable::Item(item),
1325                                      AstFragmentKind::Items, after_derive).make_items();
1326         }
1327
1328         match item.node {
1329             ast::ItemKind::Mac(..) => {
1330                 self.check_attributes(&item.attrs);
1331                 item.and_then(|item| match item.node {
1332                     ItemKind::Mac(mac) => {
1333                         self.collect(AstFragmentKind::Items, InvocationKind::Bang {
1334                             mac,
1335                             ident: Some(item.ident),
1336                             span: item.span,
1337                         }).make_items()
1338                     }
1339                     _ => unreachable!(),
1340                 })
1341             }
1342             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
1343                 if item.ident == keywords::Invalid.ident() {
1344                     return noop_fold_item(item, self);
1345                 }
1346
1347                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
1348                 let mut module = (*self.cx.current_expansion.module).clone();
1349                 module.mod_path.push(item.ident);
1350
1351                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
1352                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
1353                 // Thus, if `inner` is the dummy span, we know the module is inline.
1354                 let inline_module = item.span.contains(inner) || inner.is_dummy();
1355
1356                 if inline_module {
1357                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
1358                         self.cx.current_expansion.directory_ownership =
1359                             DirectoryOwnership::Owned { relative: None };
1360                         module.directory.push(&*path.as_str());
1361                     } else {
1362                         module.directory.push(&*item.ident.as_str());
1363                     }
1364                 } else {
1365                     let path = self.cx.parse_sess.source_map().span_to_unmapped_path(inner);
1366                     let mut path = match path {
1367                         FileName::Real(path) => path,
1368                         other => PathBuf::from(other.to_string()),
1369                     };
1370                     let directory_ownership = match path.file_name().unwrap().to_str() {
1371                         Some("mod.rs") => DirectoryOwnership::Owned { relative: None },
1372                         Some(_) => DirectoryOwnership::Owned {
1373                             relative: Some(item.ident),
1374                         },
1375                         None => DirectoryOwnership::UnownedViaMod(false),
1376                     };
1377                     path.pop();
1378                     module.directory = path;
1379                     self.cx.current_expansion.directory_ownership = directory_ownership;
1380                 }
1381
1382                 let orig_module =
1383                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
1384                 let result = noop_fold_item(item, self);
1385                 self.cx.current_expansion.module = orig_module;
1386                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
1387                 result
1388             }
1389
1390             _ => noop_fold_item(item, self),
1391         }
1392     }
1393
1394     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
1395         let item = configure!(self, item);
1396
1397         let (attr, traits, item, after_derive) = self.classify_item(item);
1398         if attr.is_some() || !traits.is_empty() {
1399             return self.collect_attr(attr, traits, Annotatable::TraitItem(P(item)),
1400                                      AstFragmentKind::TraitItems, after_derive).make_trait_items()
1401         }
1402
1403         match item.node {
1404             ast::TraitItemKind::Macro(mac) => {
1405                 let ast::TraitItem { attrs, span, .. } = item;
1406                 self.check_attributes(&attrs);
1407                 self.collect_bang(mac, span, AstFragmentKind::TraitItems).make_trait_items()
1408             }
1409             _ => fold::noop_fold_trait_item(item, self),
1410         }
1411     }
1412
1413     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
1414         let item = configure!(self, item);
1415
1416         let (attr, traits, item, after_derive) = self.classify_item(item);
1417         if attr.is_some() || !traits.is_empty() {
1418             return self.collect_attr(attr, traits, Annotatable::ImplItem(P(item)),
1419                                      AstFragmentKind::ImplItems, after_derive).make_impl_items();
1420         }
1421
1422         match item.node {
1423             ast::ImplItemKind::Macro(mac) => {
1424                 let ast::ImplItem { attrs, span, .. } = item;
1425                 self.check_attributes(&attrs);
1426                 self.collect_bang(mac, span, AstFragmentKind::ImplItems).make_impl_items()
1427             }
1428             _ => fold::noop_fold_impl_item(item, self),
1429         }
1430     }
1431
1432     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1433         let ty = match ty.node {
1434             ast::TyKind::Mac(_) => ty.into_inner(),
1435             _ => return fold::noop_fold_ty(ty, self),
1436         };
1437
1438         match ty.node {
1439             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty(),
1440             _ => unreachable!(),
1441         }
1442     }
1443
1444     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1445         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1446     }
1447
1448     fn fold_foreign_item(&mut self, foreign_item: ast::ForeignItem)
1449         -> SmallVec<[ast::ForeignItem; 1]>
1450     {
1451         let (attr, traits, foreign_item, after_derive) = self.classify_item(foreign_item);
1452
1453         if attr.is_some() || !traits.is_empty() {
1454             return self.collect_attr(attr, traits, Annotatable::ForeignItem(P(foreign_item)),
1455                                      AstFragmentKind::ForeignItems, after_derive)
1456                                      .make_foreign_items();
1457         }
1458
1459         if let ast::ForeignItemKind::Macro(mac) = foreign_item.node {
1460             self.check_attributes(&foreign_item.attrs);
1461             return self.collect_bang(mac, foreign_item.span, AstFragmentKind::ForeignItems)
1462                 .make_foreign_items();
1463         }
1464
1465         noop_fold_foreign_item(foreign_item, self)
1466     }
1467
1468     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1469         match item {
1470             ast::ItemKind::MacroDef(..) => item,
1471             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1472         }
1473     }
1474
1475     fn fold_generic_param(&mut self, param: ast::GenericParam) -> ast::GenericParam {
1476         self.cfg.disallow_cfg_on_generic_param(&param);
1477         noop_fold_generic_param(param, self)
1478     }
1479
1480     fn fold_attribute(&mut self, at: ast::Attribute) -> Option<ast::Attribute> {
1481         // turn `#[doc(include="filename")]` attributes into `#[doc(include(file="filename",
1482         // contents="file contents")]` attributes
1483         if !at.check_name("doc") {
1484             return noop_fold_attribute(at, self);
1485         }
1486
1487         if let Some(list) = at.meta_item_list() {
1488             if !list.iter().any(|it| it.check_name("include")) {
1489                 return noop_fold_attribute(at, self);
1490             }
1491
1492             let mut items = vec![];
1493
1494             for it in list {
1495                 if !it.check_name("include") {
1496                     items.push(noop_fold_meta_list_item(it, self));
1497                     continue;
1498                 }
1499
1500                 if let Some(file) = it.value_str() {
1501                     let err_count = self.cx.parse_sess.span_diagnostic.err_count();
1502                     self.check_attribute(&at);
1503                     if self.cx.parse_sess.span_diagnostic.err_count() > err_count {
1504                         // avoid loading the file if they haven't enabled the feature
1505                         return noop_fold_attribute(at, self);
1506                     }
1507
1508                     let mut buf = vec![];
1509                     let filename = self.cx.root_path.join(file.to_string());
1510
1511                     match File::open(&filename).and_then(|mut f| f.read_to_end(&mut buf)) {
1512                         Ok(..) => {}
1513                         Err(e) => {
1514                             self.cx.span_err(at.span,
1515                                              &format!("couldn't read {}: {}",
1516                                                       filename.display(),
1517                                                       e));
1518                         }
1519                     }
1520
1521                     match String::from_utf8(buf) {
1522                         Ok(src) => {
1523                             let src_interned = Symbol::intern(&src);
1524
1525                             // Add this input file to the code map to make it available as
1526                             // dependency information
1527                             self.cx.source_map().new_source_file(filename.into(), src);
1528
1529                             let include_info = vec![
1530                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1531                                         attr::mk_name_value_item_str(Ident::from_str("file"),
1532                                                                      dummy_spanned(file)))),
1533                                 dummy_spanned(ast::NestedMetaItemKind::MetaItem(
1534                                         attr::mk_name_value_item_str(Ident::from_str("contents"),
1535                                                             dummy_spanned(src_interned)))),
1536                             ];
1537
1538                             let include_ident = Ident::from_str("include");
1539                             let item = attr::mk_list_item(DUMMY_SP, include_ident, include_info);
1540                             items.push(dummy_spanned(ast::NestedMetaItemKind::MetaItem(item)));
1541                         }
1542                         Err(_) => {
1543                             self.cx.span_err(at.span,
1544                                              &format!("{} wasn't a utf-8 file",
1545                                                       filename.display()));
1546                         }
1547                     }
1548                 } else {
1549                     items.push(noop_fold_meta_list_item(it, self));
1550                 }
1551             }
1552
1553             let meta = attr::mk_list_item(DUMMY_SP, Ident::from_str("doc"), items);
1554             match at.style {
1555                 ast::AttrStyle::Inner =>
1556                     Some(attr::mk_spanned_attr_inner(at.span, at.id, meta)),
1557                 ast::AttrStyle::Outer =>
1558                     Some(attr::mk_spanned_attr_outer(at.span, at.id, meta)),
1559             }
1560         } else {
1561             noop_fold_attribute(at, self)
1562         }
1563     }
1564
1565     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1566         if self.monotonic {
1567             assert_eq!(id, ast::DUMMY_NODE_ID);
1568             self.cx.resolver.next_node_id()
1569         } else {
1570             id
1571         }
1572     }
1573 }
1574
1575 pub struct ExpansionConfig<'feat> {
1576     pub crate_name: String,
1577     pub features: Option<&'feat Features>,
1578     pub recursion_limit: usize,
1579     pub trace_mac: bool,
1580     pub should_test: bool, // If false, strip `#[test]` nodes
1581     pub single_step: bool,
1582     pub keep_macs: bool,
1583 }
1584
1585 macro_rules! feature_tests {
1586     ($( fn $getter:ident = $field:ident, )*) => {
1587         $(
1588             pub fn $getter(&self) -> bool {
1589                 match self.features {
1590                     Some(&Features { $field: true, .. }) => true,
1591                     _ => false,
1592                 }
1593             }
1594         )*
1595     }
1596 }
1597
1598 impl<'feat> ExpansionConfig<'feat> {
1599     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1600         ExpansionConfig {
1601             crate_name,
1602             features: None,
1603             recursion_limit: 1024,
1604             trace_mac: false,
1605             should_test: false,
1606             single_step: false,
1607             keep_macs: false,
1608         }
1609     }
1610
1611     feature_tests! {
1612         fn enable_quotes = quote,
1613         fn enable_asm = asm,
1614         fn enable_custom_test_frameworks = custom_test_frameworks,
1615         fn enable_global_asm = global_asm,
1616         fn enable_log_syntax = log_syntax,
1617         fn enable_concat_idents = concat_idents,
1618         fn enable_trace_macros = trace_macros,
1619         fn enable_allow_internal_unstable = allow_internal_unstable,
1620         fn enable_custom_derive = custom_derive,
1621         fn enable_format_args_nl = format_args_nl,
1622         fn macros_in_extern_enabled = macros_in_extern,
1623         fn proc_macro_hygiene = proc_macro_hygiene,
1624     }
1625
1626     fn enable_custom_inner_attributes(&self) -> bool {
1627         self.features.map_or(false, |features| {
1628             features.custom_inner_attributes || features.custom_attribute || features.rustc_attrs
1629         })
1630     }
1631 }
1632
1633 // A Marker adds the given mark to the syntax context.
1634 #[derive(Debug)]
1635 pub struct Marker(pub Mark);
1636
1637 impl Folder for Marker {
1638     fn new_span(&mut self, span: Span) -> Span {
1639         span.apply_mark(self.0)
1640     }
1641
1642     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1643         noop_fold_mac(mac, self)
1644     }
1645 }