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