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