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_err(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             self.cx.trace_macros_diag();
 395             panic!(FatalError);
 396         }
 397
 398         result
 399     }
 400
 401     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 402         let Invocation { expansion_kind: kind, .. } = invoc;
 403         let (attr, item) = match invoc.kind {
 404             InvocationKind::Attr { attr, item, .. } => (attr.unwrap(), item),
 405             _ => unreachable!(),
 406         };
 407
 408         attr::mark_used(&attr);
 409         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 410             call_site: attr.span,
 411             callee: NameAndSpan {
 412                 format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
 413                 span: None,
 414                 allow_internal_unstable: false,
 415                 allow_internal_unsafe: false,
 416             }
 417         });
 418
 419         match *ext {
 420             MultiModifier(ref mac) => {
 421                 let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
 422                 let item = mac.expand(self.cx, attr.span, &meta, item);
 423                 kind.expect_from_annotatables(item)
 424             }
 425             MultiDecorator(ref mac) => {
 426                 let mut items = Vec::new();
 427                 let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
 428                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 429                 items.push(item);
 430                 kind.expect_from_annotatables(items)
 431             }
 432             AttrProcMacro(ref mac) => {
 433                 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
 434                     Annotatable::Item(item) => token::NtItem(item),
 435                     Annotatable::TraitItem(item) => token::NtTraitItem(item.unwrap()),
 436                     Annotatable::ImplItem(item) => token::NtImplItem(item.unwrap()),
 437                 })).into();
 438                 let tok_result = mac.expand(self.cx, attr.span, attr.tokens, item_tok);
 439                 self.parse_expansion(tok_result, kind, &attr.path, attr.span)
 440             }
 441             ProcMacroDerive(..) | BuiltinDerive(..) => {
 442                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 443                 self.cx.trace_macros_diag();
 444                 kind.dummy(attr.span)
 445             }
 446             _ => {
 447                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 448                 self.cx.span_err(attr.span, msg);
 449                 self.cx.trace_macros_diag();
 450                 kind.dummy(attr.span)
 451             }
 452         }
 453     }
 454
 455     /// Expand a macro invocation. Returns the result of expansion.
 456     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 457         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 458         let (mac, ident, span) = match invoc.kind {
 459             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 460             _ => unreachable!(),
 461         };
 462         let path = &mac.node.path;
 463
 464         let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
 465         let validate_and_set_expn_info = |def_site_span,
 466                                           allow_internal_unstable,
 467                                           allow_internal_unsafe| {
 468             if ident.name != keywords::Invalid.name() {
 469                 return Err(format!("macro {}! expects no ident argument, given '{}'", path, ident));
 470             }
 471             mark.set_expn_info(ExpnInfo {
 472                 call_site: span,
 473                 callee: NameAndSpan {
 474                     format: MacroBang(Symbol::intern(&format!("{}", path))),
 475                     span: def_site_span,
 476                     allow_internal_unstable,
 477                     allow_internal_unsafe,
 478                 },
 479             });
 480             Ok(())
 481         };
 482
 483         let opt_expanded = match *ext {
 484             DeclMacro(ref expand, def_span) => {
 485                 if let Err(msg) = validate_and_set_expn_info(def_span.map(|(_, s)| s),
 486                                                              false, false) {
 487                     self.cx.span_err(path.span, &msg);
 488                     self.cx.trace_macros_diag();
 489                     return kind.dummy(span);
 490                 }
 491                 kind.make_from(expand.expand(self.cx, span, mac.node.stream()))
 492             }
 493
 494             NormalTT {
 495                 ref expander,
 496                 def_info,
 497                 allow_internal_unstable,
 498                 allow_internal_unsafe
 499             } => {
 500                 if let Err(msg) = validate_and_set_expn_info(def_info.map(|(_, s)| s),
 501                                                              allow_internal_unstable,
 502                                                              allow_internal_unsafe) {
 503                     self.cx.span_err(path.span, &msg);
 504                     self.cx.trace_macros_diag();
 505                     return kind.dummy(span);
 506                 }
 507                 kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
 508             }
 509
 510             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 511                 if ident.name == keywords::Invalid.name() {
 512                     self.cx.span_err(path.span,
 513                                     &format!("macro {}! expects an ident argument", path));
 514                     self.cx.trace_macros_diag();
 515                     return kind.dummy(span);
 516                 };
 517
 518                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 519                     call_site: span,
 520                     callee: NameAndSpan {
 521                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 522                         span: tt_span,
 523                         allow_internal_unstable,
 524                         allow_internal_unsafe: false,
 525                     }
 526                 });
 527
 528                 let input: Vec<_> = mac.node.stream().into_trees().collect();
 529                 kind.make_from(expander.expand(self.cx, span, ident, input))
 530             }
 531
 532             MultiDecorator(..) | MultiModifier(..) | AttrProcMacro(..) => {
 533                 self.cx.span_err(path.span,
 534                                  &format!("`{}` can only be used in attributes", path));
 535                 self.cx.trace_macros_diag();
 536                 return kind.dummy(span);
 537             }
 538
 539             ProcMacroDerive(..) | BuiltinDerive(..) => {
 540                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 541                 self.cx.trace_macros_diag();
 542                 return kind.dummy(span);
 543             }
 544
 545             ProcMacro(ref expandfun) => {
 546                 if ident.name != keywords::Invalid.name() {
 547                     let msg =
 548                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 549                     self.cx.span_err(path.span, &msg);
 550                     self.cx.trace_macros_diag();
 551                     return kind.dummy(span);
 552                 }
 553
 554                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 555                     call_site: span,
 556                     callee: NameAndSpan {
 557                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 558                         // FIXME procedural macros do not have proper span info
 559                         // yet, when they do, we should use it here.
 560                         span: None,
 561                         // FIXME probably want to follow macro_rules macros here.
 562                         allow_internal_unstable: false,
 563                         allow_internal_unsafe: false,
 564                     },
 565                 });
 566
 567                 let tok_result = expandfun.expand(self.cx, span, mac.node.stream());
 568                 Some(self.parse_expansion(tok_result, kind, path, span))
 569             }
 570         };
 571
 572         unwrap_or!(opt_expanded, {
 573             let msg = format!("non-{kind} macro in {kind} position: {name}",
 574                               name = path.segments[0].identifier.name, kind = kind.name());
 575             self.cx.span_err(path.span, &msg);
 576             self.cx.trace_macros_diag();
 577             kind.dummy(span)
 578         })
 579     }
 580
 581     /// Expand a derive invocation. Returns the result of expansion.
 582     fn expand_derive_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 583         let Invocation { expansion_kind: kind, .. } = invoc;
 584         let (path, item) = match invoc.kind {
 585             InvocationKind::Derive { path, item } => (path, item),
 586             _ => unreachable!(),
 587         };
 588
 589         let pretty_name = Symbol::intern(&format!("derive({})", path));
 590         let span = path.span;
 591         let attr = ast::Attribute {
 592             path, span,
 593             tokens: TokenStream::empty(),
 594             // irrelevant:
 595             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 596         };
 597
 598         let mut expn_info = ExpnInfo {
 599             call_site: span,
 600             callee: NameAndSpan {
 601                 format: MacroAttribute(pretty_name),
 602                 span: None,
 603                 allow_internal_unstable: false,
 604                 allow_internal_unsafe: false,
 605             }
 606         };
 607
 608         match *ext {
 609             ProcMacroDerive(ref ext, _) => {
 610                 invoc.expansion_data.mark.set_expn_info(expn_info);
 611                 let span = span.with_ctxt(self.cx.backtrace());
 612                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 613                     name: keywords::Invalid.name(),
 614                     span: DUMMY_SP,
 615                     node: ast::MetaItemKind::Word,
 616                 };
 617                 kind.expect_from_annotatables(ext.expand(self.cx, span, &dummy, item))
 618             }
 619             BuiltinDerive(func) => {
 620                 expn_info.callee.allow_internal_unstable = true;
 621                 invoc.expansion_data.mark.set_expn_info(expn_info);
 622                 let span = span.with_ctxt(self.cx.backtrace());
 623                 let mut items = Vec::new();
 624                 func(self.cx, span, &attr.meta().unwrap(), &item, &mut |a| items.push(a));
 625                 kind.expect_from_annotatables(items)
 626             }
 627             _ => {
 628                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 629                 self.cx.span_err(span, msg);
 630                 self.cx.trace_macros_diag();
 631                 kind.dummy(span)
 632             }
 633         }
 634     }
 635
 636     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, path: &Path, span: Span)
 637                        -> Expansion {
 638         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 639         let expansion = match parser.parse_expansion(kind, false) {
 640             Ok(expansion) => expansion,
 641             Err(mut err) => {
 642                 err.emit();
 643                 self.cx.trace_macros_diag();
 644                 return kind.dummy(span);
 645             }
 646         };
 647         parser.ensure_complete_parse(path, kind.name(), span);
 648         expansion
 649     }
 650 }
 651
 652 impl<'a> Parser<'a> {
 653     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 654                            -> PResult<'a, Expansion> {
 655         Ok(match kind {
 656             ExpansionKind::Items => {
 657                 let mut items = SmallVector::new();
 658                 while let Some(item) = self.parse_item()? {
 659                     items.push(item);
 660                 }
 661                 Expansion::Items(items)
 662             }
 663             ExpansionKind::TraitItems => {
 664                 let mut items = SmallVector::new();
 665                 while self.token != token::Eof {
 666                     items.push(self.parse_trait_item(&mut false)?);
 667                 }
 668                 Expansion::TraitItems(items)
 669             }
 670             ExpansionKind::ImplItems => {
 671                 let mut items = SmallVector::new();
 672                 while self.token != token::Eof {
 673                     items.push(self.parse_impl_item(&mut false)?);
 674                 }
 675                 Expansion::ImplItems(items)
 676             }
 677             ExpansionKind::Stmts => {
 678                 let mut stmts = SmallVector::new();
 679                 while self.token != token::Eof &&
 680                       // won't make progress on a `}`
 681                       self.token != token::CloseDelim(token::Brace) {
 682                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 683                         stmts.push(stmt);
 684                     }
 685                 }
 686                 Expansion::Stmts(stmts)
 687             }
 688             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 689             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 690             ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
 691             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 692         })
 693     }
 694
 695     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
 696         if self.token != token::Eof {
 697             let msg = format!("macro expansion ignores token `{}` and any following",
 698                               self.this_token_to_string());
 699             // Avoid emitting backtrace info twice.
 700             let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
 701             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
 702             let msg = format!("caused by the macro expansion here; the usage \
 703                                of `{}!` is likely invalid in {} context",
 704                                macro_path, kind_name);
 705             err.span_note(span, &msg).emit();
 706         }
 707     }
 708 }
 709
 710 struct InvocationCollector<'a, 'b: 'a> {
 711     cx: &'a mut ExtCtxt<'b>,
 712     cfg: StripUnconfigured<'a>,
 713     invocations: Vec<Invocation>,
 714     monotonic: bool,
 715 }
 716
 717 macro_rules! fully_configure {
 718     ($this:ident, $node:ident, $noop_fold:ident) => {
 719         match $noop_fold($node, &mut $this.cfg).pop() {
 720             Some(node) => node,
 721             None => return SmallVector::new(),
 722         }
 723     }
 724 }
 725
 726 impl<'a, 'b> InvocationCollector<'a, 'b> {
 727     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 728         let mark = Mark::fresh(self.cx.current_expansion.mark);
 729         self.invocations.push(Invocation {
 730             kind,
 731             expansion_kind,
 732             expansion_data: ExpansionData {
 733                 mark,
 734                 depth: self.cx.current_expansion.depth + 1,
 735                 ..self.cx.current_expansion.clone()
 736             },
 737         });
 738         placeholder(expansion_kind, NodeId::placeholder_from_mark(mark))
 739     }
 740
 741     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 742         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 743     }
 744
 745     fn collect_attr(&mut self,
 746                     attr: Option<ast::Attribute>,
 747                     traits: Vec<Path>,
 748                     item: Annotatable,
 749                     kind: ExpansionKind)
 750                     -> Expansion {
 751         if !traits.is_empty() &&
 752            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 753             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
 754             self.cx.trace_macros_diag();
 755             return kind.expect_from_annotatables(::std::iter::once(item));
 756         }
 757         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 758     }
 759
 760     // If `item` is an attr invocation, remove and return the macro attribute.
 761     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
 762         where T: HasAttrs,
 763     {
 764         let (mut attr, mut traits) = (None, Vec::new());
 765
 766         item = item.map_attrs(|mut attrs| {
 767             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 768                 attr = Some(legacy_attr_invoc);
 769                 return attrs;
 770             }
 771
 772             if self.cx.ecfg.proc_macro_enabled() {
 773                 attr = find_attr_invoc(&mut attrs);
 774             }
 775             traits = collect_derives(&mut self.cx, &mut attrs);
 776             attrs
 777         });
 778
 779         (attr, traits, item)
 780     }
 781
 782     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 783         self.cfg.configure(node)
 784     }
 785
 786     // Detect use of feature-gated or invalid attributes on macro invocations
 787     // since they will not be detected after macro expansion.
 788     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 789         let features = self.cx.ecfg.features.unwrap();
 790         for attr in attrs.iter() {
 791             feature_gate::check_attribute(attr, self.cx.parse_sess, features);
 792         }
 793     }
 794 }
 795
 796 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 797     attrs.iter()
 798          .position(|a| !attr::is_known(a) && !is_builtin_attr(a))
 799          .map(|i| attrs.remove(i))
 800 }
 801
 802 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 803     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 804         let mut expr = self.cfg.configure_expr(expr).unwrap();
 805         expr.node = self.cfg.configure_expr_kind(expr.node);
 806
 807         if let ast::ExprKind::Mac(mac) = expr.node {
 808             self.check_attributes(&expr.attrs);
 809             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 810         } else {
 811             P(noop_fold_expr(expr, self))
 812         }
 813     }
 814
 815     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 816         let mut expr = configure!(self, expr).unwrap();
 817         expr.node = self.cfg.configure_expr_kind(expr.node);
 818
 819         if let ast::ExprKind::Mac(mac) = expr.node {
 820             self.check_attributes(&expr.attrs);
 821             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 822         } else {
 823             Some(P(noop_fold_expr(expr, self)))
 824         }
 825     }
 826
 827     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 828         let pat = self.cfg.configure_pat(pat);
 829         match pat.node {
 830             PatKind::Mac(_) => {}
 831             _ => return noop_fold_pat(pat, self),
 832         }
 833
 834         pat.and_then(|pat| match pat.node {
 835             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 836             _ => unreachable!(),
 837         })
 838     }
 839
 840     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 841         let stmt = match self.cfg.configure_stmt(stmt) {
 842             Some(stmt) => stmt,
 843             None => return SmallVector::new(),
 844         };
 845
 846         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 847             mac.unwrap()
 848         } else {
 849             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 850             let ast::Stmt { id, node, span } = stmt;
 851             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 852                 ast::Stmt { id: id, node: node, span: span }
 853             }).collect()
 854         };
 855
 856         self.check_attributes(&attrs);
 857         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 858
 859         // If this is a macro invocation with a semicolon, then apply that
 860         // semicolon to the final statement produced by expansion.
 861         if style == MacStmtStyle::Semicolon {
 862             if let Some(stmt) = placeholder.pop() {
 863                 placeholder.push(stmt.add_trailing_semicolon());
 864             }
 865         }
 866
 867         placeholder
 868     }
 869
 870     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 871         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 872         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 873         let result = noop_fold_block(block, self);
 874         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 875         result
 876     }
 877
 878     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 879         let item = configure!(self, item);
 880
 881         let (attr, traits, mut item) = self.classify_item(item);
 882         if attr.is_some() || !traits.is_empty() {
 883             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 884             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 885         }
 886
 887         match item.node {
 888             ast::ItemKind::Mac(..) => {
 889                 self.check_attributes(&item.attrs);
 890                 item.and_then(|item| match item.node {
 891                     ItemKind::Mac(mac) => {
 892                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 893                             mac,
 894                             ident: Some(item.ident),
 895                             span: item.span,
 896                         }).make_items()
 897                     }
 898                     _ => unreachable!(),
 899                 })
 900             }
 901             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 902                 if item.ident == keywords::Invalid.ident() {
 903                     return noop_fold_item(item, self);
 904                 }
 905
 906                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 907                 let mut module = (*self.cx.current_expansion.module).clone();
 908                 module.mod_path.push(item.ident);
 909
 910                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 911                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 912                 // Thus, if `inner` is the dummy span, we know the module is inline.
 913                 let inline_module = item.span.contains(inner) || inner == DUMMY_SP;
 914
 915                 if inline_module {
 916                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 917                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 918                         module.directory.push(&*path.as_str());
 919                     } else {
 920                         module.directory.push(&*item.ident.name.as_str());
 921                     }
 922                 } else {
 923                     let mut path =
 924                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 925                     let directory_ownership = match path.file_name().unwrap().to_str() {
 926                         Some("mod.rs") => DirectoryOwnership::Owned,
 927                         _ => DirectoryOwnership::UnownedViaMod(false),
 928                     };
 929                     path.pop();
 930                     module.directory = path;
 931                     self.cx.current_expansion.directory_ownership = directory_ownership;
 932                 }
 933
 934                 let orig_module =
 935                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 936                 let result = noop_fold_item(item, self);
 937                 self.cx.current_expansion.module = orig_module;
 938                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 939                 result
 940             }
 941             // Ensure that test functions are accessible from the test harness.
 942             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 943                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 944                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 945                 }
 946                 noop_fold_item(item, self)
 947             }
 948             _ => noop_fold_item(item, self),
 949         }
 950     }
 951
 952     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 953         let item = configure!(self, item);
 954
 955         let (attr, traits, item) = self.classify_item(item);
 956         if attr.is_some() || !traits.is_empty() {
 957             let item =
 958                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 959             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 960                 .make_trait_items()
 961         }
 962
 963         match item.node {
 964             ast::TraitItemKind::Macro(mac) => {
 965                 let ast::TraitItem { attrs, span, .. } = item;
 966                 self.check_attributes(&attrs);
 967                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 968             }
 969             _ => fold::noop_fold_trait_item(item, self),
 970         }
 971     }
 972
 973     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 974         let item = configure!(self, item);
 975
 976         let (attr, traits, item) = self.classify_item(item);
 977         if attr.is_some() || !traits.is_empty() {
 978             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 979             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 980                 .make_impl_items();
 981         }
 982
 983         match item.node {
 984             ast::ImplItemKind::Macro(mac) => {
 985                 let ast::ImplItem { attrs, span, .. } = item;
 986                 self.check_attributes(&attrs);
 987                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
 988             }
 989             _ => fold::noop_fold_impl_item(item, self),
 990         }
 991     }
 992
 993     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
 994         let ty = match ty.node {
 995             ast::TyKind::Mac(_) => ty.unwrap(),
 996             _ => return fold::noop_fold_ty(ty, self),
 997         };
 998
 999         match ty.node {
1000             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
1001             _ => unreachable!(),
1002         }
1003     }
1004
1005     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1006         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1007     }
1008
1009     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1010         match item {
1011             ast::ItemKind::MacroDef(..) => item,
1012             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1013         }
1014     }
1015
1016     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1017         if self.monotonic {
1018             assert_eq!(id, ast::DUMMY_NODE_ID);
1019             self.cx.resolver.next_node_id()
1020         } else {
1021             id
1022         }
1023     }
1024 }
1025
1026 pub struct ExpansionConfig<'feat> {
1027     pub crate_name: String,
1028     pub features: Option<&'feat Features>,
1029     pub recursion_limit: usize,
1030     pub trace_mac: bool,
1031     pub should_test: bool, // If false, strip `#[test]` nodes
1032     pub single_step: bool,
1033     pub keep_macs: bool,
1034 }
1035
1036 macro_rules! feature_tests {
1037     ($( fn $getter:ident = $field:ident, )*) => {
1038         $(
1039             pub fn $getter(&self) -> bool {
1040                 match self.features {
1041                     Some(&Features { $field: true, .. }) => true,
1042                     _ => false,
1043                 }
1044             }
1045         )*
1046     }
1047 }
1048
1049 impl<'feat> ExpansionConfig<'feat> {
1050     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1051         ExpansionConfig {
1052             crate_name,
1053             features: None,
1054             recursion_limit: 1024,
1055             trace_mac: false,
1056             should_test: false,
1057             single_step: false,
1058             keep_macs: false,
1059         }
1060     }
1061
1062     feature_tests! {
1063         fn enable_quotes = quote,
1064         fn enable_asm = asm,
1065         fn enable_global_asm = global_asm,
1066         fn enable_log_syntax = log_syntax,
1067         fn enable_concat_idents = concat_idents,
1068         fn enable_trace_macros = trace_macros,
1069         fn enable_allow_internal_unstable = allow_internal_unstable,
1070         fn enable_custom_derive = custom_derive,
1071         fn proc_macro_enabled = proc_macro,
1072     }
1073 }
1074
1075 // A Marker adds the given mark to the syntax context.
1076 #[derive(Debug)]
1077 pub struct Marker(pub Mark);
1078
1079 impl Folder for Marker {
1080     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1081         ident.ctxt = ident.ctxt.apply_mark(self.0);
1082         ident
1083     }
1084
1085     fn new_span(&mut self, span: Span) -> Span {
1086         span.with_ctxt(span.ctxt().apply_mark(self.0))
1087     }
1088
1089     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1090         noop_fold_mac(mac, self)
1091     }
1092 }