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 codemap::{ExpnInfo, NameAndSpan, MacroBang, MacroAttribute};
  15 use config::{is_test_or_bench, StripUnconfigured};
  16 use errors::FatalError;
  17 use ext::base::*;
  18 use ext::derive::{add_derived_markers, collect_derives};
  19 use ext::hygiene::Mark;
  20 use ext::placeholders::{placeholder, PlaceholderExpander};
  21 use feature_gate::{self, Features, is_builtin_attr};
  22 use fold;
  23 use fold::*;
  24 use parse::{filemap_to_stream, ParseSess, DirectoryOwnership, PResult, token};
  25 use parse::parser::Parser;
  26 use print::pprust;
  27 use ptr::P;
  28 use std_inject;
  29 use symbol::Symbol;
  30 use symbol::keywords;
  31 use syntax_pos::{Span, DUMMY_SP};
  32 use tokenstream::TokenStream;
  33 use util::small_vector::SmallVector;
  34 use visit::Visitor;
  35
  36 use std::collections::HashMap;
  37 use std::mem;
  38 use std::path::PathBuf;
  39 use std::rc::Rc;
  40
  41 macro_rules! expansions {
  42     ($($kind:ident: $ty:ty [$($vec:ident, $ty_elt:ty)*], $kind_name:expr, .$make:ident,
  43             $(.$fold:ident)*  $(lift .$fold_elt:ident)*,
  44             $(.$visit:ident)*  $(lift .$visit_elt:ident)*;)*) => {
  45         #[derive(Copy, Clone, PartialEq, Eq)]
  46         pub enum ExpansionKind { OptExpr, $( $kind, )*  }
  47         pub enum Expansion { OptExpr(Option<P<ast::Expr>>), $( $kind($ty), )* }
  48
  49         impl ExpansionKind {
  50             pub fn name(self) -> &'static str {
  51                 match self {
  52                     ExpansionKind::OptExpr => "expression",
  53                     $( ExpansionKind::$kind => $kind_name, )*
  54                 }
  55             }
  56
  57             fn make_from<'a>(self, result: Box<MacResult + 'a>) -> Option<Expansion> {
  58                 match self {
  59                     ExpansionKind::OptExpr => result.make_expr().map(Some).map(Expansion::OptExpr),
  60                     $( ExpansionKind::$kind => result.$make().map(Expansion::$kind), )*
  61                 }
  62             }
  63         }
  64
  65         impl Expansion {
  66             pub fn make_opt_expr(self) -> Option<P<ast::Expr>> {
  67                 match self {
  68                     Expansion::OptExpr(expr) => expr,
  69                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  70                 }
  71             }
  72             $( pub fn $make(self) -> $ty {
  73                 match self {
  74                     Expansion::$kind(ast) => ast,
  75                     _ => panic!("Expansion::make_* called on the wrong kind of expansion"),
  76                 }
  77             } )*
  78
  79             pub fn fold_with<F: Folder>(self, folder: &mut F) -> Self {
  80                 use self::Expansion::*;
  81                 match self {
  82                     OptExpr(expr) => OptExpr(expr.and_then(|expr| folder.fold_opt_expr(expr))),
  83                     $($( $kind(ast) => $kind(folder.$fold(ast)), )*)*
  84                     $($( $kind(ast) => {
  85                         $kind(ast.into_iter().flat_map(|ast| folder.$fold_elt(ast)).collect())
  86                     }, )*)*
  87                 }
  88             }
  89
  90             pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
  91                 match *self {
  92                     Expansion::OptExpr(Some(ref expr)) => visitor.visit_expr(expr),
  93                     Expansion::OptExpr(None) => {}
  94                     $($( Expansion::$kind(ref ast) => visitor.$visit(ast), )*)*
  95                     $($( Expansion::$kind(ref ast) => for ast in &ast[..] {
  96                         visitor.$visit_elt(ast);
  97                     }, )*)*
  98                 }
  99             }
 100         }
 101
 102         impl<'a, 'b> Folder for MacroExpander<'a, 'b> {
 103             fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 104                 self.expand(Expansion::OptExpr(Some(expr))).make_opt_expr()
 105             }
 106             $($(fn $fold(&mut self, node: $ty) -> $ty {
 107                 self.expand(Expansion::$kind(node)).$make()
 108             })*)*
 109             $($(fn $fold_elt(&mut self, node: $ty_elt) -> $ty {
 110                 self.expand(Expansion::$kind(SmallVector::one(node))).$make()
 111             })*)*
 112         }
 113
 114         impl<'a> MacResult for ::ext::tt::macro_rules::ParserAnyMacro<'a> {
 115             $(fn $make(self: Box<::ext::tt::macro_rules::ParserAnyMacro<'a>>) -> Option<$ty> {
 116                 Some(self.make(ExpansionKind::$kind).$make())
 117             })*
 118         }
 119     }
 120 }
 121
 122 expansions! {
 123     Expr: P<ast::Expr> [], "expression", .make_expr, .fold_expr, .visit_expr;
 124     Pat: P<ast::Pat>   [], "pattern",    .make_pat,  .fold_pat,  .visit_pat;
 125     Ty: P<ast::Ty>     [], "type",       .make_ty,   .fold_ty,   .visit_ty;
 126     Stmts: SmallVector<ast::Stmt> [SmallVector, ast::Stmt],
 127         "statement",  .make_stmts,       lift .fold_stmt, lift .visit_stmt;
 128     Items: SmallVector<P<ast::Item>> [SmallVector, P<ast::Item>],
 129         "item",       .make_items,       lift .fold_item, lift .visit_item;
 130     TraitItems: SmallVector<ast::TraitItem> [SmallVector, ast::TraitItem],
 131         "trait item", .make_trait_items, lift .fold_trait_item, lift .visit_trait_item;
 132     ImplItems: SmallVector<ast::ImplItem> [SmallVector, ast::ImplItem],
 133         "impl item",  .make_impl_items,  lift .fold_impl_item,  lift .visit_impl_item;
 134 }
 135
 136 impl ExpansionKind {
 137     fn dummy(self, span: Span) -> Expansion {
 138         self.make_from(DummyResult::any(span)).unwrap()
 139     }
 140
 141     fn expect_from_annotatables<I: IntoIterator<Item = Annotatable>>(self, items: I) -> Expansion {
 142         let items = items.into_iter();
 143         match self {
 144             ExpansionKind::Items =>
 145                 Expansion::Items(items.map(Annotatable::expect_item).collect()),
 146             ExpansionKind::ImplItems =>
 147                 Expansion::ImplItems(items.map(Annotatable::expect_impl_item).collect()),
 148             ExpansionKind::TraitItems =>
 149                 Expansion::TraitItems(items.map(Annotatable::expect_trait_item).collect()),
 150             _ => unreachable!(),
 151         }
 152     }
 153 }
 154
 155 pub struct Invocation {
 156     pub kind: InvocationKind,
 157     expansion_kind: ExpansionKind,
 158     pub expansion_data: ExpansionData,
 159 }
 160
 161 pub enum InvocationKind {
 162     Bang {
 163         mac: ast::Mac,
 164         ident: Option<Ident>,
 165         span: Span,
 166     },
 167     Attr {
 168         attr: Option<ast::Attribute>,
 169         traits: Vec<Path>,
 170         item: Annotatable,
 171     },
 172     Derive {
 173         path: Path,
 174         item: Annotatable,
 175     },
 176 }
 177
 178 impl Invocation {
 179     fn span(&self) -> Span {
 180         match self.kind {
 181             InvocationKind::Bang { span, .. } => span,
 182             InvocationKind::Attr { attr: Some(ref attr), .. } => attr.span,
 183             InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
 184             InvocationKind::Derive { ref path, .. } => path.span,
 185         }
 186     }
 187 }
 188
 189 pub struct MacroExpander<'a, 'b:'a> {
 190     pub cx: &'a mut ExtCtxt<'b>,
 191     monotonic: bool, // c.f. `cx.monotonic_expander()`
 192 }
 193
 194 impl<'a, 'b> MacroExpander<'a, 'b> {
 195     pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
 196         MacroExpander { cx: cx, monotonic: monotonic }
 197     }
 198
 199     pub fn expand_crate(&mut self, mut krate: ast::Crate) -> ast::Crate {
 200         self.cx.crate_root = std_inject::injected_crate_name(&krate);
 201         let mut module = ModuleData {
 202             mod_path: vec![Ident::from_str(&self.cx.ecfg.crate_name)],
 203             directory: PathBuf::from(self.cx.codemap().span_to_filename(krate.span)),
 204         };
 205         module.directory.pop();
 206         self.cx.current_expansion.module = Rc::new(module);
 207
 208         let orig_mod_span = krate.module.inner;
 209
 210         let krate_item = Expansion::Items(SmallVector::one(P(ast::Item {
 211             attrs: krate.attrs,
 212             span: krate.span,
 213             node: ast::ItemKind::Mod(krate.module),
 214             ident: keywords::Invalid.ident(),
 215             id: ast::DUMMY_NODE_ID,
 216             vis: ast::Visibility::Public,
 217         })));
 218
 219         match self.expand(krate_item).make_items().pop().map(P::unwrap) {
 220             Some(ast::Item { attrs, node: ast::ItemKind::Mod(module), .. }) => {
 221                 krate.attrs = attrs;
 222                 krate.module = module;
 223             },
 224             None => {
 225                 // Resolution failed so we return an empty expansion
 226                 krate.attrs = vec![];
 227                 krate.module = ast::Mod {
 228                     inner: orig_mod_span,
 229                     items: vec![],
 230                 };
 231             },
 232             _ => unreachable!(),
 233         };
 234
 235         krate
 236     }
 237
 238     // Fully expand all the invocations in `expansion`.
 239     fn expand(&mut self, expansion: Expansion) -> Expansion {
 240         let orig_expansion_data = self.cx.current_expansion.clone();
 241         self.cx.current_expansion.depth = 0;
 242
 243         let (expansion, mut invocations) = self.collect_invocations(expansion, &[]);
 244         self.resolve_imports();
 245         invocations.reverse();
 246
 247         let mut expansions = Vec::new();
 248         let mut derives = HashMap::new();
 249         let mut undetermined_invocations = Vec::new();
 250         let (mut progress, mut force) = (false, !self.monotonic);
 251         loop {
 252             let mut invoc = if let Some(invoc) = invocations.pop() {
 253                 invoc
 254             } else {
 255                 self.resolve_imports();
 256                 if undetermined_invocations.is_empty() { break }
 257                 invocations = mem::replace(&mut undetermined_invocations, Vec::new());
 258                 force = !mem::replace(&mut progress, false);
 259                 continue
 260             };
 261
 262             let scope =
 263                 if self.monotonic { invoc.expansion_data.mark } else { orig_expansion_data.mark };
 264             let ext = match self.cx.resolver.resolve_invoc(&mut invoc, scope, force) {
 265                 Ok(ext) => Some(ext),
 266                 Err(Determinacy::Determined) => None,
 267                 Err(Determinacy::Undetermined) => {
 268                     undetermined_invocations.push(invoc);
 269                     continue
 270                 }
 271             };
 272
 273             progress = true;
 274             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
 275             self.cx.current_expansion = invoc.expansion_data.clone();
 276
 277             self.cx.current_expansion.mark = scope;
 278             // FIXME(jseyfried): Refactor out the following logic
 279             let (expansion, new_invocations) = if let Some(ext) = ext {
 280                 if let Some(ext) = ext {
 281                     let expansion = self.expand_invoc(invoc, ext);
 282                     self.collect_invocations(expansion, &[])
 283                 } else if let InvocationKind::Attr { attr: None, traits, item } = invoc.kind {
 284                     let item = item
 285                         .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
 286                     let item_with_markers =
 287                         add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
 288                     let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
 289
 290                     for path in &traits {
 291                         let mark = Mark::fresh();
 292                         derives.push(mark);
 293                         let item = match self.cx.resolver.resolve_macro(
 294                                 Mark::root(), path, MacroKind::Derive, false) {
 295                             Ok(ext) => match *ext {
 296                                 SyntaxExtension::BuiltinDerive(..) => item_with_markers.clone(),
 297                                 _ => item.clone(),
 298                             },
 299                             _ => item.clone(),
 300                         };
 301                         invocations.push(Invocation {
 302                             kind: InvocationKind::Derive { path: path.clone(), item: item },
 303                             expansion_kind: invoc.expansion_kind,
 304                             expansion_data: ExpansionData {
 305                                 mark: mark,
 306                                 ..invoc.expansion_data.clone()
 307                             },
 308                         });
 309                     }
 310                     let expansion = invoc.expansion_kind
 311                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 312                     self.collect_invocations(expansion, derives)
 313                 } else {
 314                     unreachable!()
 315                 }
 316             } else {
 317                 self.collect_invocations(invoc.expansion_kind.dummy(invoc.span()), &[])
 318             };
 319
 320             if expansions.len() < depth {
 321                 expansions.push(Vec::new());
 322             }
 323             expansions[depth - 1].push((mark, expansion));
 324             if !self.cx.ecfg.single_step {
 325                 invocations.extend(new_invocations.into_iter().rev());
 326             }
 327         }
 328
 329         self.cx.current_expansion = orig_expansion_data;
 330
 331         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 332         while let Some(expansions) = expansions.pop() {
 333             for (mark, expansion) in expansions.into_iter().rev() {
 334                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 335                 placeholder_expander.add(NodeId::placeholder_from_mark(mark), expansion, derives);
 336             }
 337         }
 338
 339         expansion.fold_with(&mut placeholder_expander)
 340     }
 341
 342     fn resolve_imports(&mut self) {
 343         if self.monotonic {
 344             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 345             self.cx.resolver.resolve_imports();
 346             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 347         }
 348     }
 349
 350     fn collect_invocations(&mut self, expansion: Expansion, derives: &[Mark])
 351                            -> (Expansion, Vec<Invocation>) {
 352         let result = {
 353             let mut collector = InvocationCollector {
 354                 cfg: StripUnconfigured {
 355                     should_test: self.cx.ecfg.should_test,
 356                     sess: self.cx.parse_sess,
 357                     features: self.cx.ecfg.features,
 358                 },
 359                 cx: self.cx,
 360                 invocations: Vec::new(),
 361                 monotonic: self.monotonic,
 362             };
 363             (expansion.fold_with(&mut collector), collector.invocations)
 364         };
 365
 366         if self.monotonic {
 367             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 368             let mark = self.cx.current_expansion.mark;
 369             self.cx.resolver.visit_expansion(mark, &result.0, derives);
 370             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 371         }
 372
 373         result
 374     }
 375
 376     fn expand_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 377         let result = match invoc.kind {
 378             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
 379             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
 380             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext),
 381         };
 382
 383         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
 384             let info = self.cx.current_expansion.mark.expn_info().unwrap();
 385             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
 386             let mut err = self.cx.struct_span_fatal(info.call_site,
 387                 &format!("recursion limit reached while expanding the macro `{}`",
 388                          info.callee.name()));
 389             err.help(&format!(
 390                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
 391                 suggested_limit));
 392             err.emit();
 393             panic!(FatalError);
 394         }
 395
 396         result
 397     }
 398
 399     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 400         let Invocation { expansion_kind: kind, .. } = invoc;
 401         let (attr, item) = match invoc.kind {
 402             InvocationKind::Attr { attr, item, .. } => (attr.unwrap(), item),
 403             _ => unreachable!(),
 404         };
 405
 406         attr::mark_used(&attr);
 407         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 408             call_site: attr.span,
 409             callee: NameAndSpan {
 410                 format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
 411                 span: None,
 412                 allow_internal_unstable: false,
 413             }
 414         });
 415
 416         match *ext {
 417             MultiModifier(ref mac) => {
 418                 let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
 419                 let item = mac.expand(self.cx, attr.span, &meta, item);
 420                 kind.expect_from_annotatables(item)
 421             }
 422             MultiDecorator(ref mac) => {
 423                 let mut items = Vec::new();
 424                 let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
 425                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 426                 items.push(item);
 427                 kind.expect_from_annotatables(items)
 428             }
 429             SyntaxExtension::AttrProcMacro(ref mac) => {
 430                 let item_toks = stream_for_item(&item, &self.cx.parse_sess);
 431
 432                 let span = Span { ctxt: self.cx.backtrace(), ..attr.span };
 433                 let tok_result = mac.expand(self.cx, attr.span, attr.tokens, item_toks);
 434                 self.parse_expansion(tok_result, kind, &attr.path, span)
 435             }
 436             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 437                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 438                 kind.dummy(attr.span)
 439             }
 440             _ => {
 441                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 442                 self.cx.span_err(attr.span, &msg);
 443                 kind.dummy(attr.span)
 444             }
 445         }
 446     }
 447
 448     /// Expand a macro invocation. Returns the result of expansion.
 449     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 450         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 451         let (mac, ident, span) = match invoc.kind {
 452             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 453             _ => unreachable!(),
 454         };
 455         let path = &mac.node.path;
 456
 457         let ident = ident.unwrap_or(keywords::Invalid.ident());
 458         let marked_tts = noop_fold_tts(mac.node.stream(), &mut Marker(mark));
 459         let opt_expanded = match *ext {
 460             NormalTT(ref expandfun, exp_span, allow_internal_unstable) => {
 461                 if ident.name != keywords::Invalid.name() {
 462                     let msg =
 463                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 464                     self.cx.span_err(path.span, &msg);
 465                     return kind.dummy(span);
 466                 }
 467
 468                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 469                     call_site: span,
 470                     callee: NameAndSpan {
 471                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 472                         span: exp_span,
 473                         allow_internal_unstable: allow_internal_unstable,
 474                     },
 475                 });
 476
 477                 kind.make_from(expandfun.expand(self.cx, span, marked_tts))
 478             }
 479
 480             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 481                 if ident.name == keywords::Invalid.name() {
 482                     self.cx.span_err(path.span,
 483                                     &format!("macro {}! expects an ident argument", path));
 484                     return kind.dummy(span);
 485                 };
 486
 487                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 488                     call_site: span,
 489                     callee: NameAndSpan {
 490                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 491                         span: tt_span,
 492                         allow_internal_unstable: allow_internal_unstable,
 493                     }
 494                 });
 495
 496                 let input: Vec<_> = marked_tts.into_trees().collect();
 497                 kind.make_from(expander.expand(self.cx, span, ident, input))
 498             }
 499
 500             MultiDecorator(..) | MultiModifier(..) | SyntaxExtension::AttrProcMacro(..) => {
 501                 self.cx.span_err(path.span,
 502                                  &format!("`{}` can only be used in attributes", path));
 503                 return kind.dummy(span);
 504             }
 505
 506             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
 507                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 508                 return kind.dummy(span);
 509             }
 510
 511             SyntaxExtension::ProcMacro(ref expandfun) => {
 512                 if ident.name != keywords::Invalid.name() {
 513                     let msg =
 514                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 515                     self.cx.span_err(path.span, &msg);
 516                     return kind.dummy(span);
 517                 }
 518
 519                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 520                     call_site: span,
 521                     callee: NameAndSpan {
 522                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 523                         // FIXME procedural macros do not have proper span info
 524                         // yet, when they do, we should use it here.
 525                         span: None,
 526                         // FIXME probably want to follow macro_rules macros here.
 527                         allow_internal_unstable: false,
 528                     },
 529                 });
 530
 531                 let tok_result = expandfun.expand(self.cx, span, marked_tts);
 532                 Some(self.parse_expansion(tok_result, kind, path, span))
 533             }
 534         };
 535
 536         let expanded = if let Some(expanded) = opt_expanded {
 537             expanded
 538         } else {
 539             let msg = format!("non-{kind} macro in {kind} position: {name}",
 540                               name = path.segments[0].identifier.name, kind = kind.name());
 541             self.cx.span_err(path.span, &msg);
 542             return kind.dummy(span);
 543         };
 544
 545         expanded.fold_with(&mut Marker(mark))
 546     }
 547
 548     /// Expand a derive invocation. Returns the result of expansion.
 549     fn expand_derive_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 550         let Invocation { expansion_kind: kind, .. } = invoc;
 551         let (path, item) = match invoc.kind {
 552             InvocationKind::Derive { path, item } => (path, item),
 553             _ => unreachable!(),
 554         };
 555
 556         let pretty_name = Symbol::intern(&format!("derive({})", path));
 557         let span = path.span;
 558         let attr = ast::Attribute {
 559             path: path, tokens: TokenStream::empty(), span: span,
 560             // irrelevant:
 561             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 562         };
 563
 564         let mut expn_info = ExpnInfo {
 565             call_site: span,
 566             callee: NameAndSpan {
 567                 format: MacroAttribute(pretty_name),
 568                 span: None,
 569                 allow_internal_unstable: false,
 570             }
 571         };
 572
 573         match *ext {
 574             SyntaxExtension::ProcMacroDerive(ref ext, _) => {
 575                 invoc.expansion_data.mark.set_expn_info(expn_info);
 576                 let span = Span { ctxt: self.cx.backtrace(), ..span };
 577                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 578                     name: keywords::Invalid.name(),
 579                     span: DUMMY_SP,
 580                     node: ast::MetaItemKind::Word,
 581                 };
 582                 kind.expect_from_annotatables(ext.expand(self.cx, span, &dummy, item))
 583             }
 584             SyntaxExtension::BuiltinDerive(func) => {
 585                 expn_info.callee.allow_internal_unstable = true;
 586                 invoc.expansion_data.mark.set_expn_info(expn_info);
 587                 let span = Span { ctxt: self.cx.backtrace(), ..span };
 588                 let mut items = Vec::new();
 589                 func(self.cx, span, &attr.meta().unwrap(), &item, &mut |a| items.push(a));
 590                 kind.expect_from_annotatables(items)
 591             }
 592             _ => {
 593                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 594                 self.cx.span_err(span, &msg);
 595                 kind.dummy(span)
 596             }
 597         }
 598     }
 599
 600     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, path: &Path, span: Span)
 601                        -> Expansion {
 602         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 603         let expansion = match parser.parse_expansion(kind, false) {
 604             Ok(expansion) => expansion,
 605             Err(mut err) => {
 606                 err.emit();
 607                 return kind.dummy(span);
 608             }
 609         };
 610         parser.ensure_complete_parse(path, kind.name(), span);
 611         // FIXME better span info
 612         expansion.fold_with(&mut ChangeSpan { span: span })
 613     }
 614 }
 615
 616 impl<'a> Parser<'a> {
 617     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 618                            -> PResult<'a, Expansion> {
 619         Ok(match kind {
 620             ExpansionKind::Items => {
 621                 let mut items = SmallVector::new();
 622                 while let Some(item) = self.parse_item()? {
 623                     items.push(item);
 624                 }
 625                 Expansion::Items(items)
 626             }
 627             ExpansionKind::TraitItems => {
 628                 let mut items = SmallVector::new();
 629                 while self.token != token::Eof {
 630                     items.push(self.parse_trait_item(&mut false)?);
 631                 }
 632                 Expansion::TraitItems(items)
 633             }
 634             ExpansionKind::ImplItems => {
 635                 let mut items = SmallVector::new();
 636                 while self.token != token::Eof {
 637                     items.push(self.parse_impl_item(&mut false)?);
 638                 }
 639                 Expansion::ImplItems(items)
 640             }
 641             ExpansionKind::Stmts => {
 642                 let mut stmts = SmallVector::new();
 643                 while self.token != token::Eof &&
 644                       // won't make progress on a `}`
 645                       self.token != token::CloseDelim(token::Brace) {
 646                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 647                         stmts.push(stmt);
 648                     }
 649                 }
 650                 Expansion::Stmts(stmts)
 651             }
 652             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 653             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 654             ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
 655             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 656         })
 657     }
 658
 659     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
 660         if self.token != token::Eof {
 661             let msg = format!("macro expansion ignores token `{}` and any following",
 662                               self.this_token_to_string());
 663             let mut err = self.diagnostic().struct_span_err(self.span, &msg);
 664             let msg = format!("caused by the macro expansion here; the usage \
 665                                of `{}!` is likely invalid in {} context",
 666                                macro_path, kind_name);
 667             err.span_note(span, &msg).emit();
 668         }
 669     }
 670 }
 671
 672 struct InvocationCollector<'a, 'b: 'a> {
 673     cx: &'a mut ExtCtxt<'b>,
 674     cfg: StripUnconfigured<'a>,
 675     invocations: Vec<Invocation>,
 676     monotonic: bool,
 677 }
 678
 679 macro_rules! fully_configure {
 680     ($this:ident, $node:ident, $noop_fold:ident) => {
 681         match $noop_fold($node, &mut $this.cfg).pop() {
 682             Some(node) => node,
 683             None => return SmallVector::new(),
 684         }
 685     }
 686 }
 687
 688 impl<'a, 'b> InvocationCollector<'a, 'b> {
 689     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 690         let mark = Mark::fresh();
 691         self.invocations.push(Invocation {
 692             kind: kind,
 693             expansion_kind: expansion_kind,
 694             expansion_data: ExpansionData {
 695                 mark: mark,
 696                 depth: self.cx.current_expansion.depth + 1,
 697                 ..self.cx.current_expansion.clone()
 698             },
 699         });
 700         placeholder(expansion_kind, NodeId::placeholder_from_mark(mark))
 701     }
 702
 703     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 704         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 705     }
 706
 707     fn collect_attr(&mut self,
 708                     attr: Option<ast::Attribute>,
 709                     traits: Vec<Path>,
 710                     item: Annotatable,
 711                     kind: ExpansionKind)
 712                     -> Expansion {
 713         if !traits.is_empty() &&
 714            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 715             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
 716             return kind.expect_from_annotatables(::std::iter::once(item));
 717         }
 718         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 719     }
 720
 721     // If `item` is an attr invocation, remove and return the macro attribute.
 722     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
 723         where T: HasAttrs,
 724     {
 725         let (mut attr, mut traits) = (None, Vec::new());
 726
 727         item = item.map_attrs(|mut attrs| {
 728             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 729                 attr = Some(legacy_attr_invoc);
 730                 return attrs;
 731             }
 732
 733             if self.cx.ecfg.proc_macro_enabled() {
 734                 attr = find_attr_invoc(&mut attrs);
 735             }
 736             traits = collect_derives(&mut self.cx, &mut attrs);
 737             attrs
 738         });
 739
 740         (attr, traits, item)
 741     }
 742
 743     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 744         self.cfg.configure(node)
 745     }
 746
 747     // Detect use of feature-gated or invalid attributes on macro invocations
 748     // since they will not be detected after macro expansion.
 749     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 750         let features = self.cx.ecfg.features.unwrap();
 751         for attr in attrs.iter() {
 752             feature_gate::check_attribute(&attr, &self.cx.parse_sess, features);
 753         }
 754     }
 755 }
 756
 757 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 758     for i in 0 .. attrs.len() {
 759         if !attr::is_known(&attrs[i]) && !is_builtin_attr(&attrs[i]) {
 760              return Some(attrs.remove(i));
 761         }
 762     }
 763
 764     None
 765 }
 766
 767 // These are pretty nasty. Ideally, we would keep the tokens around, linked from
 768 // the AST. However, we don't so we need to create new ones. Since the item might
 769 // have come from a macro expansion (possibly only in part), we can't use the
 770 // existing codemap.
 771 //
 772 // Therefore, we must use the pretty printer (yuck) to turn the AST node into a
 773 // string, which we then re-tokenise (double yuck), but first we have to patch
 774 // the pretty-printed string on to the end of the existing codemap (infinity-yuck).
 775 fn stream_for_item(item: &Annotatable, parse_sess: &ParseSess) -> TokenStream {
 776     let text = match *item {
 777         Annotatable::Item(ref i) => pprust::item_to_string(i),
 778         Annotatable::TraitItem(ref ti) => pprust::trait_item_to_string(ti),
 779         Annotatable::ImplItem(ref ii) => pprust::impl_item_to_string(ii),
 780     };
 781     string_to_stream(text, parse_sess)
 782 }
 783
 784 fn string_to_stream(text: String, parse_sess: &ParseSess) -> TokenStream {
 785     let filename = String::from("<macro expansion>");
 786     filemap_to_stream(parse_sess, parse_sess.codemap().new_filemap(filename, text))
 787 }
 788
 789 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 790     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 791         let mut expr = self.cfg.configure_expr(expr).unwrap();
 792         expr.node = self.cfg.configure_expr_kind(expr.node);
 793
 794         if let ast::ExprKind::Mac(mac) = expr.node {
 795             self.check_attributes(&expr.attrs);
 796             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 797         } else {
 798             P(noop_fold_expr(expr, self))
 799         }
 800     }
 801
 802     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 803         let mut expr = configure!(self, expr).unwrap();
 804         expr.node = self.cfg.configure_expr_kind(expr.node);
 805
 806         if let ast::ExprKind::Mac(mac) = expr.node {
 807             self.check_attributes(&expr.attrs);
 808             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 809         } else {
 810             Some(P(noop_fold_expr(expr, self)))
 811         }
 812     }
 813
 814     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 815         let pat = self.cfg.configure_pat(pat);
 816         match pat.node {
 817             PatKind::Mac(_) => {}
 818             _ => return noop_fold_pat(pat, self),
 819         }
 820
 821         pat.and_then(|pat| match pat.node {
 822             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 823             _ => unreachable!(),
 824         })
 825     }
 826
 827     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 828         let stmt = match self.cfg.configure_stmt(stmt) {
 829             Some(stmt) => stmt,
 830             None => return SmallVector::new(),
 831         };
 832
 833         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 834             mac.unwrap()
 835         } else {
 836             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 837             let ast::Stmt { id, node, span } = stmt;
 838             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 839                 ast::Stmt { id: id, node: node, span: span }
 840             }).collect()
 841         };
 842
 843         self.check_attributes(&attrs);
 844         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 845
 846         // If this is a macro invocation with a semicolon, then apply that
 847         // semicolon to the final statement produced by expansion.
 848         if style == MacStmtStyle::Semicolon {
 849             if let Some(stmt) = placeholder.pop() {
 850                 placeholder.push(stmt.add_trailing_semicolon());
 851             }
 852         }
 853
 854         placeholder
 855     }
 856
 857     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 858         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 859         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 860         let result = noop_fold_block(block, self);
 861         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 862         result
 863     }
 864
 865     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 866         let item = configure!(self, item);
 867
 868         let (attr, traits, mut item) = self.classify_item(item);
 869         if attr.is_some() || !traits.is_empty() {
 870             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 871             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 872         }
 873
 874         match item.node {
 875             ast::ItemKind::Mac(..) => {
 876                 self.check_attributes(&item.attrs);
 877                 item.and_then(|item| match item.node {
 878                     ItemKind::Mac(mac) => {
 879                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 880                             mac: mac,
 881                             ident: Some(item.ident),
 882                             span: item.span,
 883                         }).make_items()
 884                     }
 885                     _ => unreachable!(),
 886                 })
 887             }
 888             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 889                 if item.ident == keywords::Invalid.ident() {
 890                     return noop_fold_item(item, self);
 891                 }
 892
 893                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 894                 let mut module = (*self.cx.current_expansion.module).clone();
 895                 module.mod_path.push(item.ident);
 896
 897                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 898                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 899                 // Thus, if `inner` is the dummy span, we know the module is inline.
 900                 let inline_module = item.span.contains(inner) || inner == DUMMY_SP;
 901
 902                 if inline_module {
 903                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 904                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 905                         module.directory.push(&*path.as_str());
 906                     } else {
 907                         module.directory.push(&*item.ident.name.as_str());
 908                     }
 909                 } else {
 910                     let mut path =
 911                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 912                     let directory_ownership = match path.file_name().unwrap().to_str() {
 913                         Some("mod.rs") => DirectoryOwnership::Owned,
 914                         _ => DirectoryOwnership::UnownedViaMod(false),
 915                     };
 916                     path.pop();
 917                     module.directory = path;
 918                     self.cx.current_expansion.directory_ownership = directory_ownership;
 919                 }
 920
 921                 let orig_module =
 922                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 923                 let result = noop_fold_item(item, self);
 924                 self.cx.current_expansion.module = orig_module;
 925                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 926                 return result;
 927             }
 928             // Ensure that test functions are accessible from the test harness.
 929             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 930                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 931                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 932                 }
 933                 noop_fold_item(item, self)
 934             }
 935             _ => noop_fold_item(item, self),
 936         }
 937     }
 938
 939     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 940         let item = configure!(self, item);
 941
 942         let (attr, traits, item) = self.classify_item(item);
 943         if attr.is_some() || !traits.is_empty() {
 944             let item =
 945                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 946             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 947                 .make_trait_items()
 948         }
 949
 950         match item.node {
 951             ast::TraitItemKind::Macro(mac) => {
 952                 let ast::TraitItem { attrs, span, .. } = item;
 953                 self.check_attributes(&attrs);
 954                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 955             }
 956             _ => fold::noop_fold_trait_item(item, self),
 957         }
 958     }
 959
 960     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 961         let item = configure!(self, item);
 962
 963         let (attr, traits, item) = self.classify_item(item);
 964         if attr.is_some() || !traits.is_empty() {
 965             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 966             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 967                 .make_impl_items();
 968         }
 969
 970         match item.node {
 971             ast::ImplItemKind::Macro(mac) => {
 972                 let ast::ImplItem { attrs, span, .. } = item;
 973                 self.check_attributes(&attrs);
 974                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
 975             }
 976             _ => fold::noop_fold_impl_item(item, self),
 977         }
 978     }
 979
 980     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
 981         let ty = match ty.node {
 982             ast::TyKind::Mac(_) => ty.unwrap(),
 983             _ => return fold::noop_fold_ty(ty, self),
 984         };
 985
 986         match ty.node {
 987             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
 988             _ => unreachable!(),
 989         }
 990     }
 991
 992     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
 993         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
 994     }
 995
 996     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
 997         match item {
 998             ast::ItemKind::MacroDef(..) => item,
 999             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1000         }
1001     }
1002
1003     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1004         if self.monotonic {
1005             assert_eq!(id, ast::DUMMY_NODE_ID);
1006             self.cx.resolver.next_node_id()
1007         } else {
1008             id
1009         }
1010     }
1011 }
1012
1013 pub struct ExpansionConfig<'feat> {
1014     pub crate_name: String,
1015     pub features: Option<&'feat Features>,
1016     pub recursion_limit: usize,
1017     pub trace_mac: bool,
1018     pub should_test: bool, // If false, strip `#[test]` nodes
1019     pub single_step: bool,
1020     pub keep_macs: bool,
1021 }
1022
1023 macro_rules! feature_tests {
1024     ($( fn $getter:ident = $field:ident, )*) => {
1025         $(
1026             pub fn $getter(&self) -> bool {
1027                 match self.features {
1028                     Some(&Features { $field: true, .. }) => true,
1029                     _ => false,
1030                 }
1031             }
1032         )*
1033     }
1034 }
1035
1036 impl<'feat> ExpansionConfig<'feat> {
1037     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1038         ExpansionConfig {
1039             crate_name: crate_name,
1040             features: None,
1041             recursion_limit: 1024,
1042             trace_mac: false,
1043             should_test: false,
1044             single_step: false,
1045             keep_macs: false,
1046         }
1047     }
1048
1049     feature_tests! {
1050         fn enable_quotes = quote,
1051         fn enable_asm = asm,
1052         fn enable_global_asm = global_asm,
1053         fn enable_log_syntax = log_syntax,
1054         fn enable_concat_idents = concat_idents,
1055         fn enable_trace_macros = trace_macros,
1056         fn enable_allow_internal_unstable = allow_internal_unstable,
1057         fn enable_custom_derive = custom_derive,
1058         fn proc_macro_enabled = proc_macro,
1059     }
1060 }
1061
1062 // A Marker adds the given mark to the syntax context.
1063 struct Marker(Mark);
1064
1065 impl Folder for Marker {
1066     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1067         ident.ctxt = ident.ctxt.apply_mark(self.0);
1068         ident
1069     }
1070
1071     fn new_span(&mut self, mut span: Span) -> Span {
1072         span.ctxt = span.ctxt.apply_mark(self.0);
1073         span
1074     }
1075
1076     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1077         noop_fold_mac(mac, self)
1078     }
1079 }