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,
 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, span,
 583             tokens: TokenStream::empty(),
 584             // irrelevant:
 585             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 586         };
 587
 588         let mut expn_info = ExpnInfo {
 589             call_site: span,
 590             callee: NameAndSpan {
 591                 format: MacroAttribute(pretty_name),
 592                 span: None,
 593                 allow_internal_unstable: false,
 594                 allow_internal_unsafe: false,
 595             }
 596         };
 597
 598         match *ext {
 599             ProcMacroDerive(ref ext, _) => {
 600                 invoc.expansion_data.mark.set_expn_info(expn_info);
 601                 let span = Span { ctxt: self.cx.backtrace(), ..span };
 602                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 603                     name: keywords::Invalid.name(),
 604                     span: DUMMY_SP,
 605                     node: ast::MetaItemKind::Word,
 606                 };
 607                 kind.expect_from_annotatables(ext.expand(self.cx, span, &dummy, item))
 608             }
 609             BuiltinDerive(func) => {
 610                 expn_info.callee.allow_internal_unstable = true;
 611                 invoc.expansion_data.mark.set_expn_info(expn_info);
 612                 let span = Span { ctxt: self.cx.backtrace(), ..span };
 613                 let mut items = Vec::new();
 614                 func(self.cx, span, &attr.meta().unwrap(), &item, &mut |a| items.push(a));
 615                 kind.expect_from_annotatables(items)
 616             }
 617             _ => {
 618                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 619                 self.cx.span_err(span, msg);
 620                 kind.dummy(span)
 621             }
 622         }
 623     }
 624
 625     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, path: &Path, span: Span)
 626                        -> Expansion {
 627         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 628         let expansion = match parser.parse_expansion(kind, false) {
 629             Ok(expansion) => expansion,
 630             Err(mut err) => {
 631                 err.emit();
 632                 return kind.dummy(span);
 633             }
 634         };
 635         parser.ensure_complete_parse(path, kind.name(), span);
 636         expansion
 637     }
 638 }
 639
 640 impl<'a> Parser<'a> {
 641     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 642                            -> PResult<'a, Expansion> {
 643         Ok(match kind {
 644             ExpansionKind::Items => {
 645                 let mut items = SmallVector::new();
 646                 while let Some(item) = self.parse_item()? {
 647                     items.push(item);
 648                 }
 649                 Expansion::Items(items)
 650             }
 651             ExpansionKind::TraitItems => {
 652                 let mut items = SmallVector::new();
 653                 while self.token != token::Eof {
 654                     items.push(self.parse_trait_item(&mut false)?);
 655                 }
 656                 Expansion::TraitItems(items)
 657             }
 658             ExpansionKind::ImplItems => {
 659                 let mut items = SmallVector::new();
 660                 while self.token != token::Eof {
 661                     items.push(self.parse_impl_item(&mut false)?);
 662                 }
 663                 Expansion::ImplItems(items)
 664             }
 665             ExpansionKind::Stmts => {
 666                 let mut stmts = SmallVector::new();
 667                 while self.token != token::Eof &&
 668                       // won't make progress on a `}`
 669                       self.token != token::CloseDelim(token::Brace) {
 670                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 671                         stmts.push(stmt);
 672                     }
 673                 }
 674                 Expansion::Stmts(stmts)
 675             }
 676             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 677             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 678             ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
 679             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 680         })
 681     }
 682
 683     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
 684         if self.token != token::Eof {
 685             let msg = format!("macro expansion ignores token `{}` and any following",
 686                               self.this_token_to_string());
 687             let mut def_site_span = self.span;
 688             def_site_span.ctxt = SyntaxContext::empty(); // Avoid emitting backtrace info twice.
 689             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
 690             let msg = format!("caused by the macro expansion here; the usage \
 691                                of `{}!` is likely invalid in {} context",
 692                                macro_path, kind_name);
 693             err.span_note(span, &msg).emit();
 694         }
 695     }
 696 }
 697
 698 struct InvocationCollector<'a, 'b: 'a> {
 699     cx: &'a mut ExtCtxt<'b>,
 700     cfg: StripUnconfigured<'a>,
 701     invocations: Vec<Invocation>,
 702     monotonic: bool,
 703 }
 704
 705 macro_rules! fully_configure {
 706     ($this:ident, $node:ident, $noop_fold:ident) => {
 707         match $noop_fold($node, &mut $this.cfg).pop() {
 708             Some(node) => node,
 709             None => return SmallVector::new(),
 710         }
 711     }
 712 }
 713
 714 impl<'a, 'b> InvocationCollector<'a, 'b> {
 715     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 716         let mark = Mark::fresh(self.cx.current_expansion.mark);
 717         self.invocations.push(Invocation {
 718             kind,
 719             expansion_kind,
 720             expansion_data: ExpansionData {
 721                 mark,
 722                 depth: self.cx.current_expansion.depth + 1,
 723                 ..self.cx.current_expansion.clone()
 724             },
 725         });
 726         placeholder(expansion_kind, NodeId::placeholder_from_mark(mark))
 727     }
 728
 729     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 730         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 731     }
 732
 733     fn collect_attr(&mut self,
 734                     attr: Option<ast::Attribute>,
 735                     traits: Vec<Path>,
 736                     item: Annotatable,
 737                     kind: ExpansionKind)
 738                     -> Expansion {
 739         if !traits.is_empty() &&
 740            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 741             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
 742             return kind.expect_from_annotatables(::std::iter::once(item));
 743         }
 744         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 745     }
 746
 747     // If `item` is an attr invocation, remove and return the macro attribute.
 748     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
 749         where T: HasAttrs,
 750     {
 751         let (mut attr, mut traits) = (None, Vec::new());
 752
 753         item = item.map_attrs(|mut attrs| {
 754             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 755                 attr = Some(legacy_attr_invoc);
 756                 return attrs;
 757             }
 758
 759             if self.cx.ecfg.proc_macro_enabled() {
 760                 attr = find_attr_invoc(&mut attrs);
 761             }
 762             traits = collect_derives(&mut self.cx, &mut attrs);
 763             attrs
 764         });
 765
 766         (attr, traits, item)
 767     }
 768
 769     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 770         self.cfg.configure(node)
 771     }
 772
 773     // Detect use of feature-gated or invalid attributes on macro invocations
 774     // since they will not be detected after macro expansion.
 775     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 776         let features = self.cx.ecfg.features.unwrap();
 777         for attr in attrs.iter() {
 778             feature_gate::check_attribute(attr, self.cx.parse_sess, features);
 779         }
 780     }
 781 }
 782
 783 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 784     attrs.iter()
 785          .position(|a| !attr::is_known(a) && !is_builtin_attr(a))
 786          .map(|i| attrs.remove(i))
 787 }
 788
 789 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 790     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 791         let mut expr = self.cfg.configure_expr(expr).unwrap();
 792         expr.node = self.cfg.configure_expr_kind(expr.node);
 793
 794         if let ast::ExprKind::Mac(mac) = expr.node {
 795             self.check_attributes(&expr.attrs);
 796             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 797         } else {
 798             P(noop_fold_expr(expr, self))
 799         }
 800     }
 801
 802     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 803         let mut expr = configure!(self, expr).unwrap();
 804         expr.node = self.cfg.configure_expr_kind(expr.node);
 805
 806         if let ast::ExprKind::Mac(mac) = expr.node {
 807             self.check_attributes(&expr.attrs);
 808             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 809         } else {
 810             Some(P(noop_fold_expr(expr, self)))
 811         }
 812     }
 813
 814     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 815         let pat = self.cfg.configure_pat(pat);
 816         match pat.node {
 817             PatKind::Mac(_) => {}
 818             _ => return noop_fold_pat(pat, self),
 819         }
 820
 821         pat.and_then(|pat| match pat.node {
 822             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 823             _ => unreachable!(),
 824         })
 825     }
 826
 827     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 828         let stmt = match self.cfg.configure_stmt(stmt) {
 829             Some(stmt) => stmt,
 830             None => return SmallVector::new(),
 831         };
 832
 833         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 834             mac.unwrap()
 835         } else {
 836             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 837             let ast::Stmt { id, node, span } = stmt;
 838             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 839                 ast::Stmt { id: id, node: node, span: span }
 840             }).collect()
 841         };
 842
 843         self.check_attributes(&attrs);
 844         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 845
 846         // If this is a macro invocation with a semicolon, then apply that
 847         // semicolon to the final statement produced by expansion.
 848         if style == MacStmtStyle::Semicolon {
 849             if let Some(stmt) = placeholder.pop() {
 850                 placeholder.push(stmt.add_trailing_semicolon());
 851             }
 852         }
 853
 854         placeholder
 855     }
 856
 857     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 858         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 859         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 860         let result = noop_fold_block(block, self);
 861         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 862         result
 863     }
 864
 865     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 866         let item = configure!(self, item);
 867
 868         let (attr, traits, mut item) = self.classify_item(item);
 869         if attr.is_some() || !traits.is_empty() {
 870             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 871             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 872         }
 873
 874         match item.node {
 875             ast::ItemKind::Mac(..) => {
 876                 self.check_attributes(&item.attrs);
 877                 item.and_then(|item| match item.node {
 878                     ItemKind::Mac(mac) => {
 879                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 880                             mac,
 881                             ident: Some(item.ident),
 882                             span: item.span,
 883                         }).make_items()
 884                     }
 885                     _ => unreachable!(),
 886                 })
 887             }
 888             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 889                 if item.ident == keywords::Invalid.ident() {
 890                     return noop_fold_item(item, self);
 891                 }
 892
 893                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 894                 let mut module = (*self.cx.current_expansion.module).clone();
 895                 module.mod_path.push(item.ident);
 896
 897                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 898                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 899                 // Thus, if `inner` is the dummy span, we know the module is inline.
 900                 let inline_module = item.span.contains(inner) || inner == DUMMY_SP;
 901
 902                 if inline_module {
 903                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 904                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 905                         module.directory.push(&*path.as_str());
 906                     } else {
 907                         module.directory.push(&*item.ident.name.as_str());
 908                     }
 909                 } else {
 910                     let mut path =
 911                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 912                     let directory_ownership = match path.file_name().unwrap().to_str() {
 913                         Some("mod.rs") => DirectoryOwnership::Owned,
 914                         _ => DirectoryOwnership::UnownedViaMod(false),
 915                     };
 916                     path.pop();
 917                     module.directory = path;
 918                     self.cx.current_expansion.directory_ownership = directory_ownership;
 919                 }
 920
 921                 let orig_module =
 922                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 923                 let result = noop_fold_item(item, self);
 924                 self.cx.current_expansion.module = orig_module;
 925                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 926                 result
 927             }
 928             // Ensure that test functions are accessible from the test harness.
 929             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 930                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 931                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 932                 }
 933                 noop_fold_item(item, self)
 934             }
 935             _ => noop_fold_item(item, self),
 936         }
 937     }
 938
 939     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 940         let item = configure!(self, item);
 941
 942         let (attr, traits, item) = self.classify_item(item);
 943         if attr.is_some() || !traits.is_empty() {
 944             let item =
 945                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 946             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 947                 .make_trait_items()
 948         }
 949
 950         match item.node {
 951             ast::TraitItemKind::Macro(mac) => {
 952                 let ast::TraitItem { attrs, span, .. } = item;
 953                 self.check_attributes(&attrs);
 954                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 955             }
 956             _ => fold::noop_fold_trait_item(item, self),
 957         }
 958     }
 959
 960     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 961         let item = configure!(self, item);
 962
 963         let (attr, traits, item) = self.classify_item(item);
 964         if attr.is_some() || !traits.is_empty() {
 965             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 966             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 967                 .make_impl_items();
 968         }
 969
 970         match item.node {
 971             ast::ImplItemKind::Macro(mac) => {
 972                 let ast::ImplItem { attrs, span, .. } = item;
 973                 self.check_attributes(&attrs);
 974                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
 975             }
 976             _ => fold::noop_fold_impl_item(item, self),
 977         }
 978     }
 979
 980     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
 981         let ty = match ty.node {
 982             ast::TyKind::Mac(_) => ty.unwrap(),
 983             _ => return fold::noop_fold_ty(ty, self),
 984         };
 985
 986         match ty.node {
 987             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
 988             _ => unreachable!(),
 989         }
 990     }
 991
 992     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
 993         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
 994     }
 995
 996     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
 997         match item {
 998             ast::ItemKind::MacroDef(..) => item,
 999             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1000         }
1001     }
1002
1003     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1004         if self.monotonic {
1005             assert_eq!(id, ast::DUMMY_NODE_ID);
1006             self.cx.resolver.next_node_id()
1007         } else {
1008             id
1009         }
1010     }
1011 }
1012
1013 pub struct ExpansionConfig<'feat> {
1014     pub crate_name: String,
1015     pub features: Option<&'feat Features>,
1016     pub recursion_limit: usize,
1017     pub trace_mac: bool,
1018     pub should_test: bool, // If false, strip `#[test]` nodes
1019     pub single_step: bool,
1020     pub keep_macs: bool,
1021 }
1022
1023 macro_rules! feature_tests {
1024     ($( fn $getter:ident = $field:ident, )*) => {
1025         $(
1026             pub fn $getter(&self) -> bool {
1027                 match self.features {
1028                     Some(&Features { $field: true, .. }) => true,
1029                     _ => false,
1030                 }
1031             }
1032         )*
1033     }
1034 }
1035
1036 impl<'feat> ExpansionConfig<'feat> {
1037     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1038         ExpansionConfig {
1039             crate_name,
1040             features: None,
1041             recursion_limit: 1024,
1042             trace_mac: false,
1043             should_test: false,
1044             single_step: false,
1045             keep_macs: false,
1046         }
1047     }
1048
1049     feature_tests! {
1050         fn enable_quotes = quote,
1051         fn enable_asm = asm,
1052         fn enable_global_asm = global_asm,
1053         fn enable_log_syntax = log_syntax,
1054         fn enable_concat_idents = concat_idents,
1055         fn enable_trace_macros = trace_macros,
1056         fn enable_allow_internal_unstable = allow_internal_unstable,
1057         fn enable_custom_derive = custom_derive,
1058         fn proc_macro_enabled = proc_macro,
1059     }
1060 }
1061
1062 // A Marker adds the given mark to the syntax context.
1063 #[derive(Debug)]
1064 pub struct Marker(pub Mark);
1065
1066 impl Folder for Marker {
1067     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1068         ident.ctxt = ident.ctxt.apply_mark(self.0);
1069         ident
1070     }
1071
1072     fn new_span(&mut self, mut span: Span) -> Span {
1073         span.ctxt = span.ctxt.apply_mark(self.0);
1074         span
1075     }
1076
1077     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1078         noop_fold_mac(mac, self)
1079     }
1080 }