src/librustc_resolve/macros.rs

   1 // Copyright 2016 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 {Module, Resolver};
  12 use build_reduced_graph::BuildReducedGraphVisitor;
  13 use rustc::hir::def_id::{CRATE_DEF_INDEX, DefIndex};
  14 use rustc::hir::map::{self, DefCollector};
  15 use std::cell::Cell;
  16 use std::rc::Rc;
  17 use syntax::ast;
  18 use syntax::errors::DiagnosticBuilder;
  19 use syntax::ext::base::{self, Determinacy, MultiModifier, MultiDecorator};
  20 use syntax::ext::base::{NormalTT, SyntaxExtension};
  21 use syntax::ext::expand::Expansion;
  22 use syntax::ext::hygiene::Mark;
  23 use syntax::ext::tt::macro_rules;
  24 use syntax::parse::token::intern;
  25 use syntax::util::lev_distance::find_best_match_for_name;
  26 use syntax_pos::Span;
  27
  28 #[derive(Clone)]
  29 pub struct InvocationData<'a> {
  30     pub module: Cell<Module<'a>>,
  31     pub def_index: DefIndex,
  32     // True if this expansion is in a `const_integer` position, for example `[u32; m!()]`.
  33     // c.f. `DefCollector::visit_ast_const_integer`.
  34     pub const_integer: bool,
  35     // The scope in which the invocation path is resolved.
  36     pub legacy_scope: Cell<LegacyScope<'a>>,
  37     // The smallest scope that includes this invocation's expansion,
  38     // or `Empty` if this invocation has not been expanded yet.
  39     pub expansion: Cell<LegacyScope<'a>>,
  40 }
  41
  42 impl<'a> InvocationData<'a> {
  43     pub fn root(graph_root: Module<'a>) -> Self {
  44         InvocationData {
  45             module: Cell::new(graph_root),
  46             def_index: CRATE_DEF_INDEX,
  47             const_integer: false,
  48             legacy_scope: Cell::new(LegacyScope::Empty),
  49             expansion: Cell::new(LegacyScope::Empty),
  50         }
  51     }
  52 }
  53
  54 #[derive(Copy, Clone)]
  55 pub enum LegacyScope<'a> {
  56     Empty,
  57     Invocation(&'a InvocationData<'a>), // The scope of the invocation, not including its expansion
  58     Expansion(&'a InvocationData<'a>), // The scope of the invocation, including its expansion
  59     Binding(&'a LegacyBinding<'a>),
  60 }
  61
  62 impl<'a> LegacyScope<'a> {
  63     fn simplify_expansion(mut invoc: &'a InvocationData<'a>) -> Self {
  64         while let LegacyScope::Invocation(_) = invoc.expansion.get() {
  65             match invoc.legacy_scope.get() {
  66                 LegacyScope::Expansion(new_invoc) => invoc = new_invoc,
  67                 LegacyScope::Binding(_) => break,
  68                 scope @ _ => return scope,
  69             }
  70         }
  71         LegacyScope::Expansion(invoc)
  72     }
  73 }
  74
  75 pub struct LegacyBinding<'a> {
  76     pub parent: LegacyScope<'a>,
  77     pub name: ast::Name,
  78     ext: Rc<SyntaxExtension>,
  79     pub span: Span,
  80 }
  81
  82 impl<'a> base::Resolver for Resolver<'a> {
  83     fn next_node_id(&mut self) -> ast::NodeId {
  84         self.session.next_node_id()
  85     }
  86
  87     fn get_module_scope(&mut self, id: ast::NodeId) -> Mark {
  88         let mark = Mark::fresh();
  89         let module = self.module_map[&id];
  90         self.invocations.insert(mark, self.arenas.alloc_invocation_data(InvocationData {
  91             module: Cell::new(module),
  92             def_index: module.def_id().unwrap().index,
  93             const_integer: false,
  94             legacy_scope: Cell::new(LegacyScope::Empty),
  95             expansion: Cell::new(LegacyScope::Empty),
  96         }));
  97         mark
  98     }
  99
 100     fn visit_expansion(&mut self, mark: Mark, expansion: &Expansion) {
 101         let invocation = self.invocations[&mark];
 102         self.collect_def_ids(invocation, expansion);
 103
 104         self.current_module = invocation.module.get();
 105         let mut visitor = BuildReducedGraphVisitor {
 106             resolver: self,
 107             legacy_scope: LegacyScope::Invocation(invocation),
 108             expansion: mark,
 109         };
 110         expansion.visit_with(&mut visitor);
 111         invocation.expansion.set(visitor.legacy_scope);
 112     }
 113
 114     fn add_macro(&mut self, scope: Mark, mut def: ast::MacroDef, export: bool) {
 115         if &def.ident.name.as_str() == "macro_rules" {
 116             self.session.span_err(def.span, "user-defined macros may not be named `macro_rules`");
 117         }
 118
 119         let invocation = self.invocations[&scope];
 120         let binding = self.arenas.alloc_legacy_binding(LegacyBinding {
 121             parent: invocation.legacy_scope.get(),
 122             name: def.ident.name,
 123             ext: Rc::new(macro_rules::compile(&self.session.parse_sess, &def)),
 124             span: def.span,
 125         });
 126         invocation.legacy_scope.set(LegacyScope::Binding(binding));
 127         self.macro_names.insert(def.ident.name);
 128
 129         if export {
 130             def.id = self.next_node_id();
 131             self.exported_macros.push(def);
 132         }
 133     }
 134
 135     fn add_ext(&mut self, ident: ast::Ident, ext: Rc<SyntaxExtension>) {
 136         if let NormalTT(..) = *ext {
 137             self.macro_names.insert(ident.name);
 138         }
 139         self.builtin_macros.insert(ident.name, ext);
 140     }
 141
 142     fn add_expansions_at_stmt(&mut self, id: ast::NodeId, macros: Vec<Mark>) {
 143         self.macros_at_scope.insert(id, macros);
 144     }
 145
 146     fn find_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
 147         for i in 0..attrs.len() {
 148             let name = intern(&attrs[i].name());
 149             match self.builtin_macros.get(&name) {
 150                 Some(ext) => match **ext {
 151                     MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
 152                         return Some(attrs.remove(i))
 153                     }
 154                     _ => {}
 155                 },
 156                 None => {}
 157             }
 158         }
 159         None
 160     }
 161
 162     fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, force: bool)
 163                      -> Result<Rc<SyntaxExtension>, Determinacy> {
 164         if path.segments.len() > 1 || path.global || !path.segments[0].parameters.is_empty() {
 165             self.session.span_err(path.span, "expected macro name without module separators");
 166             return Err(Determinacy::Determined);
 167         }
 168         let name = path.segments[0].identifier.name;
 169
 170         let invocation = self.invocations[&scope];
 171         if let LegacyScope::Expansion(parent) = invocation.legacy_scope.get() {
 172             invocation.legacy_scope.set(LegacyScope::simplify_expansion(parent));
 173         }
 174         self.resolve_macro_name(invocation.legacy_scope.get(), name).ok_or_else(|| {
 175             if force {
 176                 let msg = format!("macro undefined: '{}!'", name);
 177                 let mut err = self.session.struct_span_err(path.span, &msg);
 178                 self.suggest_macro_name(&name.as_str(), &mut err);
 179                 err.emit();
 180                 Determinacy::Determined
 181             } else {
 182                 Determinacy::Undetermined
 183             }
 184         })
 185     }
 186 }
 187
 188 impl<'a> Resolver<'a> {
 189     pub fn resolve_macro_name(&mut self, mut scope: LegacyScope<'a>, name: ast::Name)
 190                               -> Option<Rc<SyntaxExtension>> {
 191         let mut possible_time_travel = None;
 192         let mut relative_depth: u32 = 0;
 193         loop {
 194             scope = match scope {
 195                 LegacyScope::Empty => break,
 196                 LegacyScope::Expansion(invocation) => {
 197                     if let LegacyScope::Empty = invocation.expansion.get() {
 198                         if possible_time_travel.is_none() {
 199                             possible_time_travel = Some(scope);
 200                         }
 201                         invocation.legacy_scope.get()
 202                     } else {
 203                         relative_depth += 1;
 204                         invocation.expansion.get()
 205                     }
 206                 }
 207                 LegacyScope::Invocation(invocation) => {
 208                     relative_depth = relative_depth.saturating_sub(1);
 209                     invocation.legacy_scope.get()
 210                 }
 211                 LegacyScope::Binding(binding) => {
 212                     if binding.name == name {
 213                         if let Some(scope) = possible_time_travel {
 214                             // Check for disallowed shadowing later
 215                             self.lexical_macro_resolutions.push((name, scope));
 216                         } else if relative_depth > 0 {
 217                             self.disallowed_shadowing.push(binding);
 218                         }
 219                         return Some(binding.ext.clone());
 220                     }
 221                     binding.parent
 222                 }
 223             };
 224         }
 225
 226         if let Some(scope) = possible_time_travel {
 227             self.lexical_macro_resolutions.push((name, scope));
 228         }
 229         self.builtin_macros.get(&name).cloned()
 230     }
 231
 232     fn suggest_macro_name(&mut self, name: &str, err: &mut DiagnosticBuilder<'a>) {
 233         if let Some(suggestion) = find_best_match_for_name(self.macro_names.iter(), name, None) {
 234             if suggestion != name {
 235                 err.help(&format!("did you mean `{}!`?", suggestion));
 236             } else {
 237                 err.help(&format!("have you added the `#[macro_use]` on the module/import?"));
 238             }
 239         }
 240     }
 241
 242     fn collect_def_ids(&mut self, invocation: &'a InvocationData<'a>, expansion: &Expansion) {
 243         let Resolver { ref mut invocations, arenas, graph_root, .. } = *self;
 244         let InvocationData { def_index, const_integer, .. } = *invocation;
 245
 246         let visit_macro_invoc = &mut |invoc: map::MacroInvocationData| {
 247             invocations.entry(invoc.mark).or_insert_with(|| {
 248                 arenas.alloc_invocation_data(InvocationData {
 249                     def_index: invoc.def_index,
 250                     const_integer: invoc.const_integer,
 251                     module: Cell::new(graph_root),
 252                     expansion: Cell::new(LegacyScope::Empty),
 253                     legacy_scope: Cell::new(LegacyScope::Empty),
 254                 })
 255             });
 256         };
 257
 258         let mut def_collector = DefCollector::new(&mut self.definitions);
 259         def_collector.visit_macro_invoc = Some(visit_macro_invoc);
 260         def_collector.with_parent(def_index, |def_collector| {
 261             if const_integer {
 262                 if let Expansion::Expr(ref expr) = *expansion {
 263                     def_collector.visit_ast_const_integer(expr);
 264                 }
 265             }
 266             expansion.visit_with(def_collector)
 267         });
 268     }
 269 }