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 derive_allowed = match item {
 286                         Annotatable::Item(ref item) => match item.node {
 287                             ast::ItemKind::Struct(..) |
 288                             ast::ItemKind::Enum(..) |
 289                             ast::ItemKind::Union(..) => true,
 290                             _ => false,
 291                         },
 292                         _ => false,
 293                     };
 294                     if !derive_allowed {
 295                         let span = item.attrs().iter()
 296                             .find(|attr| attr.check_name("derive"))
 297                             .expect("`derive` attribute should exist").span;
 298                         self.cx.span_err(span,
 299                                          "`derive` may only be applied to structs, enums \
 300                                           and unions");
 301                     }
 302
 303                     let item = item
 304                         .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
 305                     let item_with_markers =
 306                         add_derived_markers(&mut self.cx, item.span(), &traits, item.clone());
 307                     let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
 308
 309                     for path in &traits {
 310                         let mark = Mark::fresh(self.cx.current_expansion.mark);
 311                         derives.push(mark);
 312                         let item = match self.cx.resolver.resolve_macro(
 313                                 Mark::root(), path, MacroKind::Derive, false) {
 314                             Ok(ext) => match *ext {
 315                                 BuiltinDerive(..) => item_with_markers.clone(),
 316                                 _ => item.clone(),
 317                             },
 318                             _ => item.clone(),
 319                         };
 320                         invocations.push(Invocation {
 321                             kind: InvocationKind::Derive { path: path.clone(), item: item },
 322                             expansion_kind: invoc.expansion_kind,
 323                             expansion_data: ExpansionData {
 324                                 mark,
 325                                 ..invoc.expansion_data.clone()
 326                             },
 327                         });
 328                     }
 329                     let expansion = invoc.expansion_kind
 330                         .expect_from_annotatables(::std::iter::once(item_with_markers));
 331                     self.collect_invocations(expansion, derives)
 332                 } else {
 333                     unreachable!()
 334                 }
 335             } else {
 336                 self.collect_invocations(invoc.expansion_kind.dummy(invoc.span()), &[])
 337             };
 338
 339             if expansions.len() < depth {
 340                 expansions.push(Vec::new());
 341             }
 342             expansions[depth - 1].push((mark, expansion));
 343             if !self.cx.ecfg.single_step {
 344                 invocations.extend(new_invocations.into_iter().rev());
 345             }
 346         }
 347
 348         self.cx.current_expansion = orig_expansion_data;
 349
 350         let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
 351         while let Some(expansions) = expansions.pop() {
 352             for (mark, expansion) in expansions.into_iter().rev() {
 353                 let derives = derives.remove(&mark).unwrap_or_else(Vec::new);
 354                 placeholder_expander.add(NodeId::placeholder_from_mark(mark), expansion, derives);
 355             }
 356         }
 357
 358         expansion.fold_with(&mut placeholder_expander)
 359     }
 360
 361     fn resolve_imports(&mut self) {
 362         if self.monotonic {
 363             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 364             self.cx.resolver.resolve_imports();
 365             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 366         }
 367     }
 368
 369     fn collect_invocations(&mut self, expansion: Expansion, derives: &[Mark])
 370                            -> (Expansion, Vec<Invocation>) {
 371         let result = {
 372             let mut collector = InvocationCollector {
 373                 cfg: StripUnconfigured {
 374                     should_test: self.cx.ecfg.should_test,
 375                     sess: self.cx.parse_sess,
 376                     features: self.cx.ecfg.features,
 377                 },
 378                 cx: self.cx,
 379                 invocations: Vec::new(),
 380                 monotonic: self.monotonic,
 381             };
 382             (expansion.fold_with(&mut collector), collector.invocations)
 383         };
 384
 385         if self.monotonic {
 386             let err_count = self.cx.parse_sess.span_diagnostic.err_count();
 387             let mark = self.cx.current_expansion.mark;
 388             self.cx.resolver.visit_expansion(mark, &result.0, derives);
 389             self.cx.resolve_err_count += self.cx.parse_sess.span_diagnostic.err_count() - err_count;
 390         }
 391
 392         result
 393     }
 394
 395     fn expand_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 396         let result = match invoc.kind {
 397             InvocationKind::Bang { .. } => self.expand_bang_invoc(invoc, ext),
 398             InvocationKind::Attr { .. } => self.expand_attr_invoc(invoc, ext),
 399             InvocationKind::Derive { .. } => self.expand_derive_invoc(invoc, ext),
 400         };
 401
 402         if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
 403             let info = self.cx.current_expansion.mark.expn_info().unwrap();
 404             let suggested_limit = self.cx.ecfg.recursion_limit * 2;
 405             let mut err = self.cx.struct_span_err(info.call_site,
 406                 &format!("recursion limit reached while expanding the macro `{}`",
 407                          info.callee.name()));
 408             err.help(&format!(
 409                 "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
 410                 suggested_limit));
 411             err.emit();
 412             self.cx.trace_macros_diag();
 413             panic!(FatalError);
 414         }
 415
 416         result
 417     }
 418
 419     fn expand_attr_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 420         let Invocation { expansion_kind: kind, .. } = invoc;
 421         let (attr, item) = match invoc.kind {
 422             InvocationKind::Attr { attr, item, .. } => (attr.unwrap(), item),
 423             _ => unreachable!(),
 424         };
 425
 426         attr::mark_used(&attr);
 427         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 428             call_site: attr.span,
 429             callee: NameAndSpan {
 430                 format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
 431                 span: None,
 432                 allow_internal_unstable: false,
 433                 allow_internal_unsafe: false,
 434             }
 435         });
 436
 437         match *ext {
 438             MultiModifier(ref mac) => {
 439                 let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
 440                 let item = mac.expand(self.cx, attr.span, &meta, item);
 441                 kind.expect_from_annotatables(item)
 442             }
 443             MultiDecorator(ref mac) => {
 444                 let mut items = Vec::new();
 445                 let meta = panictry!(attr.parse_meta(self.cx.parse_sess));
 446                 mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
 447                 items.push(item);
 448                 kind.expect_from_annotatables(items)
 449             }
 450             AttrProcMacro(ref mac) => {
 451                 let item_tok = TokenTree::Token(DUMMY_SP, Token::interpolated(match item {
 452                     Annotatable::Item(item) => token::NtItem(item),
 453                     Annotatable::TraitItem(item) => token::NtTraitItem(item.unwrap()),
 454                     Annotatable::ImplItem(item) => token::NtImplItem(item.unwrap()),
 455                 })).into();
 456                 let tok_result = mac.expand(self.cx, attr.span, attr.tokens, item_tok);
 457                 self.parse_expansion(tok_result, kind, &attr.path, attr.span)
 458             }
 459             ProcMacroDerive(..) | BuiltinDerive(..) => {
 460                 self.cx.span_err(attr.span, &format!("`{}` is a derive mode", attr.path));
 461                 self.cx.trace_macros_diag();
 462                 kind.dummy(attr.span)
 463             }
 464             _ => {
 465                 let msg = &format!("macro `{}` may not be used in attributes", attr.path);
 466                 self.cx.span_err(attr.span, msg);
 467                 self.cx.trace_macros_diag();
 468                 kind.dummy(attr.span)
 469             }
 470         }
 471     }
 472
 473     /// Expand a macro invocation. Returns the result of expansion.
 474     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 475         let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
 476         let (mac, ident, span) = match invoc.kind {
 477             InvocationKind::Bang { mac, ident, span } => (mac, ident, span),
 478             _ => unreachable!(),
 479         };
 480         let path = &mac.node.path;
 481
 482         let ident = ident.unwrap_or_else(|| keywords::Invalid.ident());
 483         let validate_and_set_expn_info = |def_site_span,
 484                                           allow_internal_unstable,
 485                                           allow_internal_unsafe| {
 486             if ident.name != keywords::Invalid.name() {
 487                 return Err(format!("macro {}! expects no ident argument, given '{}'", path, ident));
 488             }
 489             mark.set_expn_info(ExpnInfo {
 490                 call_site: span,
 491                 callee: NameAndSpan {
 492                     format: MacroBang(Symbol::intern(&format!("{}", path))),
 493                     span: def_site_span,
 494                     allow_internal_unstable,
 495                     allow_internal_unsafe,
 496                 },
 497             });
 498             Ok(())
 499         };
 500
 501         let opt_expanded = match *ext {
 502             DeclMacro(ref expand, def_span) => {
 503                 if let Err(msg) = validate_and_set_expn_info(def_span.map(|(_, s)| s),
 504                                                              false, false) {
 505                     self.cx.span_err(path.span, &msg);
 506                     self.cx.trace_macros_diag();
 507                     return kind.dummy(span);
 508                 }
 509                 kind.make_from(expand.expand(self.cx, span, mac.node.stream()))
 510             }
 511
 512             NormalTT {
 513                 ref expander,
 514                 def_info,
 515                 allow_internal_unstable,
 516                 allow_internal_unsafe
 517             } => {
 518                 if let Err(msg) = validate_and_set_expn_info(def_info.map(|(_, s)| s),
 519                                                              allow_internal_unstable,
 520                                                              allow_internal_unsafe) {
 521                     self.cx.span_err(path.span, &msg);
 522                     self.cx.trace_macros_diag();
 523                     return kind.dummy(span);
 524                 }
 525                 kind.make_from(expander.expand(self.cx, span, mac.node.stream()))
 526             }
 527
 528             IdentTT(ref expander, tt_span, allow_internal_unstable) => {
 529                 if ident.name == keywords::Invalid.name() {
 530                     self.cx.span_err(path.span,
 531                                     &format!("macro {}! expects an ident argument", path));
 532                     self.cx.trace_macros_diag();
 533                     return kind.dummy(span);
 534                 };
 535
 536                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 537                     call_site: span,
 538                     callee: NameAndSpan {
 539                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 540                         span: tt_span,
 541                         allow_internal_unstable,
 542                         allow_internal_unsafe: false,
 543                     }
 544                 });
 545
 546                 let input: Vec<_> = mac.node.stream().into_trees().collect();
 547                 kind.make_from(expander.expand(self.cx, span, ident, input))
 548             }
 549
 550             MultiDecorator(..) | MultiModifier(..) | AttrProcMacro(..) => {
 551                 self.cx.span_err(path.span,
 552                                  &format!("`{}` can only be used in attributes", path));
 553                 self.cx.trace_macros_diag();
 554                 return kind.dummy(span);
 555             }
 556
 557             ProcMacroDerive(..) | BuiltinDerive(..) => {
 558                 self.cx.span_err(path.span, &format!("`{}` is a derive mode", path));
 559                 self.cx.trace_macros_diag();
 560                 return kind.dummy(span);
 561             }
 562
 563             ProcMacro(ref expandfun) => {
 564                 if ident.name != keywords::Invalid.name() {
 565                     let msg =
 566                         format!("macro {}! expects no ident argument, given '{}'", path, ident);
 567                     self.cx.span_err(path.span, &msg);
 568                     self.cx.trace_macros_diag();
 569                     return kind.dummy(span);
 570                 }
 571
 572                 invoc.expansion_data.mark.set_expn_info(ExpnInfo {
 573                     call_site: span,
 574                     callee: NameAndSpan {
 575                         format: MacroBang(Symbol::intern(&format!("{}", path))),
 576                         // FIXME procedural macros do not have proper span info
 577                         // yet, when they do, we should use it here.
 578                         span: None,
 579                         // FIXME probably want to follow macro_rules macros here.
 580                         allow_internal_unstable: false,
 581                         allow_internal_unsafe: false,
 582                     },
 583                 });
 584
 585                 let tok_result = expandfun.expand(self.cx, span, mac.node.stream());
 586                 Some(self.parse_expansion(tok_result, kind, path, span))
 587             }
 588         };
 589
 590         unwrap_or!(opt_expanded, {
 591             let msg = format!("non-{kind} macro in {kind} position: {name}",
 592                               name = path.segments[0].identifier.name, kind = kind.name());
 593             self.cx.span_err(path.span, &msg);
 594             self.cx.trace_macros_diag();
 595             kind.dummy(span)
 596         })
 597     }
 598
 599     /// Expand a derive invocation. Returns the result of expansion.
 600     fn expand_derive_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
 601         let Invocation { expansion_kind: kind, .. } = invoc;
 602         let (path, item) = match invoc.kind {
 603             InvocationKind::Derive { path, item } => (path, item),
 604             _ => unreachable!(),
 605         };
 606
 607         let pretty_name = Symbol::intern(&format!("derive({})", path));
 608         let span = path.span;
 609         let attr = ast::Attribute {
 610             path, span,
 611             tokens: TokenStream::empty(),
 612             // irrelevant:
 613             id: ast::AttrId(0), style: ast::AttrStyle::Outer, is_sugared_doc: false,
 614         };
 615
 616         let mut expn_info = ExpnInfo {
 617             call_site: span,
 618             callee: NameAndSpan {
 619                 format: MacroAttribute(pretty_name),
 620                 span: None,
 621                 allow_internal_unstable: false,
 622                 allow_internal_unsafe: false,
 623             }
 624         };
 625
 626         match *ext {
 627             ProcMacroDerive(ref ext, _) => {
 628                 invoc.expansion_data.mark.set_expn_info(expn_info);
 629                 let span = span.with_ctxt(self.cx.backtrace());
 630                 let dummy = ast::MetaItem { // FIXME(jseyfried) avoid this
 631                     name: keywords::Invalid.name(),
 632                     span: DUMMY_SP,
 633                     node: ast::MetaItemKind::Word,
 634                 };
 635                 kind.expect_from_annotatables(ext.expand(self.cx, span, &dummy, item))
 636             }
 637             BuiltinDerive(func) => {
 638                 expn_info.callee.allow_internal_unstable = true;
 639                 invoc.expansion_data.mark.set_expn_info(expn_info);
 640                 let span = span.with_ctxt(self.cx.backtrace());
 641                 let mut items = Vec::new();
 642                 func(self.cx, span, &attr.meta().unwrap(), &item, &mut |a| items.push(a));
 643                 kind.expect_from_annotatables(items)
 644             }
 645             _ => {
 646                 let msg = &format!("macro `{}` may not be used for derive attributes", attr.path);
 647                 self.cx.span_err(span, msg);
 648                 self.cx.trace_macros_diag();
 649                 kind.dummy(span)
 650             }
 651         }
 652     }
 653
 654     fn parse_expansion(&mut self, toks: TokenStream, kind: ExpansionKind, path: &Path, span: Span)
 655                        -> Expansion {
 656         let mut parser = self.cx.new_parser_from_tts(&toks.into_trees().collect::<Vec<_>>());
 657         let expansion = match parser.parse_expansion(kind, false) {
 658             Ok(expansion) => expansion,
 659             Err(mut err) => {
 660                 err.emit();
 661                 self.cx.trace_macros_diag();
 662                 return kind.dummy(span);
 663             }
 664         };
 665         parser.ensure_complete_parse(path, kind.name(), span);
 666         expansion
 667     }
 668 }
 669
 670 impl<'a> Parser<'a> {
 671     pub fn parse_expansion(&mut self, kind: ExpansionKind, macro_legacy_warnings: bool)
 672                            -> PResult<'a, Expansion> {
 673         Ok(match kind {
 674             ExpansionKind::Items => {
 675                 let mut items = SmallVector::new();
 676                 while let Some(item) = self.parse_item()? {
 677                     items.push(item);
 678                 }
 679                 Expansion::Items(items)
 680             }
 681             ExpansionKind::TraitItems => {
 682                 let mut items = SmallVector::new();
 683                 while self.token != token::Eof {
 684                     items.push(self.parse_trait_item(&mut false)?);
 685                 }
 686                 Expansion::TraitItems(items)
 687             }
 688             ExpansionKind::ImplItems => {
 689                 let mut items = SmallVector::new();
 690                 while self.token != token::Eof {
 691                     items.push(self.parse_impl_item(&mut false)?);
 692                 }
 693                 Expansion::ImplItems(items)
 694             }
 695             ExpansionKind::Stmts => {
 696                 let mut stmts = SmallVector::new();
 697                 while self.token != token::Eof &&
 698                       // won't make progress on a `}`
 699                       self.token != token::CloseDelim(token::Brace) {
 700                     if let Some(stmt) = self.parse_full_stmt(macro_legacy_warnings)? {
 701                         stmts.push(stmt);
 702                     }
 703                 }
 704                 Expansion::Stmts(stmts)
 705             }
 706             ExpansionKind::Expr => Expansion::Expr(self.parse_expr()?),
 707             ExpansionKind::OptExpr => Expansion::OptExpr(Some(self.parse_expr()?)),
 708             ExpansionKind::Ty => Expansion::Ty(self.parse_ty()?),
 709             ExpansionKind::Pat => Expansion::Pat(self.parse_pat()?),
 710         })
 711     }
 712
 713     pub fn ensure_complete_parse(&mut self, macro_path: &Path, kind_name: &str, span: Span) {
 714         if self.token != token::Eof {
 715             let msg = format!("macro expansion ignores token `{}` and any following",
 716                               self.this_token_to_string());
 717             // Avoid emitting backtrace info twice.
 718             let def_site_span = self.span.with_ctxt(SyntaxContext::empty());
 719             let mut err = self.diagnostic().struct_span_err(def_site_span, &msg);
 720             let msg = format!("caused by the macro expansion here; the usage \
 721                                of `{}!` is likely invalid in {} context",
 722                                macro_path, kind_name);
 723             err.span_note(span, &msg).emit();
 724         }
 725     }
 726 }
 727
 728 struct InvocationCollector<'a, 'b: 'a> {
 729     cx: &'a mut ExtCtxt<'b>,
 730     cfg: StripUnconfigured<'a>,
 731     invocations: Vec<Invocation>,
 732     monotonic: bool,
 733 }
 734
 735 macro_rules! fully_configure {
 736     ($this:ident, $node:ident, $noop_fold:ident) => {
 737         match $noop_fold($node, &mut $this.cfg).pop() {
 738             Some(node) => node,
 739             None => return SmallVector::new(),
 740         }
 741     }
 742 }
 743
 744 impl<'a, 'b> InvocationCollector<'a, 'b> {
 745     fn collect(&mut self, expansion_kind: ExpansionKind, kind: InvocationKind) -> Expansion {
 746         let mark = Mark::fresh(self.cx.current_expansion.mark);
 747         self.invocations.push(Invocation {
 748             kind,
 749             expansion_kind,
 750             expansion_data: ExpansionData {
 751                 mark,
 752                 depth: self.cx.current_expansion.depth + 1,
 753                 ..self.cx.current_expansion.clone()
 754             },
 755         });
 756         placeholder(expansion_kind, NodeId::placeholder_from_mark(mark))
 757     }
 758
 759     fn collect_bang(&mut self, mac: ast::Mac, span: Span, kind: ExpansionKind) -> Expansion {
 760         self.collect(kind, InvocationKind::Bang { mac: mac, ident: None, span: span })
 761     }
 762
 763     fn collect_attr(&mut self,
 764                     attr: Option<ast::Attribute>,
 765                     traits: Vec<Path>,
 766                     item: Annotatable,
 767                     kind: ExpansionKind)
 768                     -> Expansion {
 769         if !traits.is_empty() &&
 770            (kind == ExpansionKind::TraitItems || kind == ExpansionKind::ImplItems) {
 771             self.cx.span_err(traits[0].span, "`derive` can be only be applied to items");
 772             self.cx.trace_macros_diag();
 773             return kind.expect_from_annotatables(::std::iter::once(item));
 774         }
 775         self.collect(kind, InvocationKind::Attr { attr: attr, traits: traits, item: item })
 776     }
 777
 778     // If `item` is an attr invocation, remove and return the macro attribute.
 779     fn classify_item<T>(&mut self, mut item: T) -> (Option<ast::Attribute>, Vec<Path>, T)
 780         where T: HasAttrs,
 781     {
 782         let (mut attr, mut traits) = (None, Vec::new());
 783
 784         item = item.map_attrs(|mut attrs| {
 785             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs) {
 786                 attr = Some(legacy_attr_invoc);
 787                 return attrs;
 788             }
 789
 790             if self.cx.ecfg.proc_macro_enabled() {
 791                 attr = find_attr_invoc(&mut attrs);
 792             }
 793             traits = collect_derives(&mut self.cx, &mut attrs);
 794             attrs
 795         });
 796
 797         (attr, traits, item)
 798     }
 799
 800     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
 801         self.cfg.configure(node)
 802     }
 803
 804     // Detect use of feature-gated or invalid attributes on macro invocations
 805     // since they will not be detected after macro expansion.
 806     fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
 807         let features = self.cx.ecfg.features.unwrap();
 808         for attr in attrs.iter() {
 809             feature_gate::check_attribute(attr, self.cx.parse_sess, features);
 810         }
 811     }
 812 }
 813
 814 pub fn find_attr_invoc(attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 815     attrs.iter()
 816          .position(|a| !attr::is_known(a) && !is_builtin_attr(a))
 817          .map(|i| attrs.remove(i))
 818 }
 819
 820 impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
 821     fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 822         let mut expr = self.cfg.configure_expr(expr).unwrap();
 823         expr.node = self.cfg.configure_expr_kind(expr.node);
 824
 825         if let ast::ExprKind::Mac(mac) = expr.node {
 826             self.check_attributes(&expr.attrs);
 827             self.collect_bang(mac, expr.span, ExpansionKind::Expr).make_expr()
 828         } else {
 829             P(noop_fold_expr(expr, self))
 830         }
 831     }
 832
 833     fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
 834         let mut expr = configure!(self, expr).unwrap();
 835         expr.node = self.cfg.configure_expr_kind(expr.node);
 836
 837         if let ast::ExprKind::Mac(mac) = expr.node {
 838             self.check_attributes(&expr.attrs);
 839             self.collect_bang(mac, expr.span, ExpansionKind::OptExpr).make_opt_expr()
 840         } else {
 841             Some(P(noop_fold_expr(expr, self)))
 842         }
 843     }
 844
 845     fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 846         let pat = self.cfg.configure_pat(pat);
 847         match pat.node {
 848             PatKind::Mac(_) => {}
 849             _ => return noop_fold_pat(pat, self),
 850         }
 851
 852         pat.and_then(|pat| match pat.node {
 853             PatKind::Mac(mac) => self.collect_bang(mac, pat.span, ExpansionKind::Pat).make_pat(),
 854             _ => unreachable!(),
 855         })
 856     }
 857
 858     fn fold_stmt(&mut self, stmt: ast::Stmt) -> SmallVector<ast::Stmt> {
 859         let stmt = match self.cfg.configure_stmt(stmt) {
 860             Some(stmt) => stmt,
 861             None => return SmallVector::new(),
 862         };
 863
 864         let (mac, style, attrs) = if let StmtKind::Mac(mac) = stmt.node {
 865             mac.unwrap()
 866         } else {
 867             // The placeholder expander gives ids to statements, so we avoid folding the id here.
 868             let ast::Stmt { id, node, span } = stmt;
 869             return noop_fold_stmt_kind(node, self).into_iter().map(|node| {
 870                 ast::Stmt { id: id, node: node, span: span }
 871             }).collect()
 872         };
 873
 874         self.check_attributes(&attrs);
 875         let mut placeholder = self.collect_bang(mac, stmt.span, ExpansionKind::Stmts).make_stmts();
 876
 877         // If this is a macro invocation with a semicolon, then apply that
 878         // semicolon to the final statement produced by expansion.
 879         if style == MacStmtStyle::Semicolon {
 880             if let Some(stmt) = placeholder.pop() {
 881                 placeholder.push(stmt.add_trailing_semicolon());
 882             }
 883         }
 884
 885         placeholder
 886     }
 887
 888     fn fold_block(&mut self, block: P<Block>) -> P<Block> {
 889         let old_directory_ownership = self.cx.current_expansion.directory_ownership;
 890         self.cx.current_expansion.directory_ownership = DirectoryOwnership::UnownedViaBlock;
 891         let result = noop_fold_block(block, self);
 892         self.cx.current_expansion.directory_ownership = old_directory_ownership;
 893         result
 894     }
 895
 896     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVector<P<ast::Item>> {
 897         let item = configure!(self, item);
 898
 899         let (attr, traits, mut item) = self.classify_item(item);
 900         if attr.is_some() || !traits.is_empty() {
 901             let item = Annotatable::Item(fully_configure!(self, item, noop_fold_item));
 902             return self.collect_attr(attr, traits, item, ExpansionKind::Items).make_items();
 903         }
 904
 905         match item.node {
 906             ast::ItemKind::Mac(..) => {
 907                 self.check_attributes(&item.attrs);
 908                 item.and_then(|item| match item.node {
 909                     ItemKind::Mac(mac) => {
 910                         self.collect(ExpansionKind::Items, InvocationKind::Bang {
 911                             mac,
 912                             ident: Some(item.ident),
 913                             span: item.span,
 914                         }).make_items()
 915                     }
 916                     _ => unreachable!(),
 917                 })
 918             }
 919             ast::ItemKind::Mod(ast::Mod { inner, .. }) => {
 920                 if item.ident == keywords::Invalid.ident() {
 921                     return noop_fold_item(item, self);
 922                 }
 923
 924                 let orig_directory_ownership = self.cx.current_expansion.directory_ownership;
 925                 let mut module = (*self.cx.current_expansion.module).clone();
 926                 module.mod_path.push(item.ident);
 927
 928                 // Detect if this is an inline module (`mod m { ... }` as opposed to `mod m;`).
 929                 // In the non-inline case, `inner` is never the dummy span (c.f. `parse_item_mod`).
 930                 // Thus, if `inner` is the dummy span, we know the module is inline.
 931                 let inline_module = item.span.contains(inner) || inner == DUMMY_SP;
 932
 933                 if inline_module {
 934                     if let Some(path) = attr::first_attr_value_str_by_name(&item.attrs, "path") {
 935                         self.cx.current_expansion.directory_ownership = DirectoryOwnership::Owned;
 936                         module.directory.push(&*path.as_str());
 937                     } else {
 938                         module.directory.push(&*item.ident.name.as_str());
 939                     }
 940                 } else {
 941                     let mut path =
 942                         PathBuf::from(self.cx.parse_sess.codemap().span_to_filename(inner));
 943                     let directory_ownership = match path.file_name().unwrap().to_str() {
 944                         Some("mod.rs") => DirectoryOwnership::Owned,
 945                         _ => DirectoryOwnership::UnownedViaMod(false),
 946                     };
 947                     path.pop();
 948                     module.directory = path;
 949                     self.cx.current_expansion.directory_ownership = directory_ownership;
 950                 }
 951
 952                 let orig_module =
 953                     mem::replace(&mut self.cx.current_expansion.module, Rc::new(module));
 954                 let result = noop_fold_item(item, self);
 955                 self.cx.current_expansion.module = orig_module;
 956                 self.cx.current_expansion.directory_ownership = orig_directory_ownership;
 957                 result
 958             }
 959             // Ensure that test functions are accessible from the test harness.
 960             ast::ItemKind::Fn(..) if self.cx.ecfg.should_test => {
 961                 if item.attrs.iter().any(|attr| is_test_or_bench(attr)) {
 962                     item = item.map(|mut item| { item.vis = ast::Visibility::Public; item });
 963                 }
 964                 noop_fold_item(item, self)
 965             }
 966             _ => noop_fold_item(item, self),
 967         }
 968     }
 969
 970     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVector<ast::TraitItem> {
 971         let item = configure!(self, item);
 972
 973         let (attr, traits, item) = self.classify_item(item);
 974         if attr.is_some() || !traits.is_empty() {
 975             let item =
 976                 Annotatable::TraitItem(P(fully_configure!(self, item, noop_fold_trait_item)));
 977             return self.collect_attr(attr, traits, item, ExpansionKind::TraitItems)
 978                 .make_trait_items()
 979         }
 980
 981         match item.node {
 982             ast::TraitItemKind::Macro(mac) => {
 983                 let ast::TraitItem { attrs, span, .. } = item;
 984                 self.check_attributes(&attrs);
 985                 self.collect_bang(mac, span, ExpansionKind::TraitItems).make_trait_items()
 986             }
 987             _ => fold::noop_fold_trait_item(item, self),
 988         }
 989     }
 990
 991     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVector<ast::ImplItem> {
 992         let item = configure!(self, item);
 993
 994         let (attr, traits, item) = self.classify_item(item);
 995         if attr.is_some() || !traits.is_empty() {
 996             let item = Annotatable::ImplItem(P(fully_configure!(self, item, noop_fold_impl_item)));
 997             return self.collect_attr(attr, traits, item, ExpansionKind::ImplItems)
 998                 .make_impl_items();
 999         }
1000
1001         match item.node {
1002             ast::ImplItemKind::Macro(mac) => {
1003                 let ast::ImplItem { attrs, span, .. } = item;
1004                 self.check_attributes(&attrs);
1005                 self.collect_bang(mac, span, ExpansionKind::ImplItems).make_impl_items()
1006             }
1007             _ => fold::noop_fold_impl_item(item, self),
1008         }
1009     }
1010
1011     fn fold_ty(&mut self, ty: P<ast::Ty>) -> P<ast::Ty> {
1012         let ty = match ty.node {
1013             ast::TyKind::Mac(_) => ty.unwrap(),
1014             _ => return fold::noop_fold_ty(ty, self),
1015         };
1016
1017         match ty.node {
1018             ast::TyKind::Mac(mac) => self.collect_bang(mac, ty.span, ExpansionKind::Ty).make_ty(),
1019             _ => unreachable!(),
1020         }
1021     }
1022
1023     fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod {
1024         noop_fold_foreign_mod(self.cfg.configure_foreign_mod(foreign_mod), self)
1025     }
1026
1027     fn fold_item_kind(&mut self, item: ast::ItemKind) -> ast::ItemKind {
1028         match item {
1029             ast::ItemKind::MacroDef(..) => item,
1030             _ => noop_fold_item_kind(self.cfg.configure_item_kind(item), self),
1031         }
1032     }
1033
1034     fn new_id(&mut self, id: ast::NodeId) -> ast::NodeId {
1035         if self.monotonic {
1036             assert_eq!(id, ast::DUMMY_NODE_ID);
1037             self.cx.resolver.next_node_id()
1038         } else {
1039             id
1040         }
1041     }
1042 }
1043
1044 pub struct ExpansionConfig<'feat> {
1045     pub crate_name: String,
1046     pub features: Option<&'feat Features>,
1047     pub recursion_limit: usize,
1048     pub trace_mac: bool,
1049     pub should_test: bool, // If false, strip `#[test]` nodes
1050     pub single_step: bool,
1051     pub keep_macs: bool,
1052 }
1053
1054 macro_rules! feature_tests {
1055     ($( fn $getter:ident = $field:ident, )*) => {
1056         $(
1057             pub fn $getter(&self) -> bool {
1058                 match self.features {
1059                     Some(&Features { $field: true, .. }) => true,
1060                     _ => false,
1061                 }
1062             }
1063         )*
1064     }
1065 }
1066
1067 impl<'feat> ExpansionConfig<'feat> {
1068     pub fn default(crate_name: String) -> ExpansionConfig<'static> {
1069         ExpansionConfig {
1070             crate_name,
1071             features: None,
1072             recursion_limit: 1024,
1073             trace_mac: false,
1074             should_test: false,
1075             single_step: false,
1076             keep_macs: false,
1077         }
1078     }
1079
1080     feature_tests! {
1081         fn enable_quotes = quote,
1082         fn enable_asm = asm,
1083         fn enable_global_asm = global_asm,
1084         fn enable_log_syntax = log_syntax,
1085         fn enable_concat_idents = concat_idents,
1086         fn enable_trace_macros = trace_macros,
1087         fn enable_allow_internal_unstable = allow_internal_unstable,
1088         fn enable_custom_derive = custom_derive,
1089         fn proc_macro_enabled = proc_macro,
1090     }
1091 }
1092
1093 // A Marker adds the given mark to the syntax context.
1094 #[derive(Debug)]
1095 pub struct Marker(pub Mark);
1096
1097 impl Folder for Marker {
1098     fn fold_ident(&mut self, mut ident: Ident) -> Ident {
1099         ident.ctxt = ident.ctxt.apply_mark(self.0);
1100         ident
1101     }
1102
1103     fn new_span(&mut self, span: Span) -> Span {
1104         span.with_ctxt(span.ctxt().apply_mark(self.0))
1105     }
1106
1107     fn fold_mac(&mut self, mac: ast::Mac) -> ast::Mac {
1108         noop_fold_mac(mac, self)
1109     }
1110 }