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