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 Resolver;
  12 use rustc::middle::cstore::LoadedMacro;
  13 use rustc::util::nodemap::FnvHashMap;
  14 use std::cell::RefCell;
  15 use std::mem;
  16 use std::rc::Rc;
  17 use syntax::ast::{self, Name};
  18 use syntax::errors::DiagnosticBuilder;
  19 use syntax::ext::base::{self, MultiModifier, MultiDecorator, MultiItemModifier};
  20 use syntax::ext::base::{NormalTT, Resolver as SyntaxResolver, SyntaxExtension};
  21 use syntax::ext::expand::{Expansion, Invocation, InvocationKind};
  22 use syntax::ext::hygiene::Mark;
  23 use syntax::ext::tt::macro_rules;
  24 use syntax::feature_gate::{self, emit_feature_err};
  25 use syntax::parse::token::{self, intern};
  26 use syntax::util::lev_distance::find_best_match_for_name;
  27 use syntax::visit::{self, Visitor};
  28 use syntax_pos::Span;
  29
  30 #[derive(Clone, Default)]
  31 pub struct ExpansionData {
  32     module: Rc<ModuleData>,
  33 }
  34
  35 // FIXME(jseyfried): merge with `::ModuleS`.
  36 #[derive(Default)]
  37 struct ModuleData {
  38     parent: Option<Rc<ModuleData>>,
  39     macros: RefCell<FnvHashMap<Name, Rc<SyntaxExtension>>>,
  40     macros_escape: bool,
  41 }
  42
  43 impl<'a> base::Resolver for Resolver<'a> {
  44     fn next_node_id(&mut self) -> ast::NodeId {
  45         self.session.next_node_id()
  46     }
  47
  48     fn visit_expansion(&mut self, mark: Mark, expansion: &Expansion) {
  49         expansion.visit_with(&mut ExpansionVisitor {
  50             current_module: self.expansion_data[&mark.as_u32()].module.clone(),
  51             resolver: self,
  52         });
  53     }
  54
  55     fn add_macro(&mut self, scope: Mark, mut def: ast::MacroDef) {
  56         if &def.ident.name.as_str() == "macro_rules" {
  57             self.session.span_err(def.span, "user-defined macros may not be named `macro_rules`");
  58         }
  59         if def.use_locally {
  60             let ext = macro_rules::compile(&self.session.parse_sess, &def);
  61             self.add_ext(scope, def.ident, Rc::new(ext));
  62         }
  63         if def.export {
  64             def.id = self.next_node_id();
  65             self.exported_macros.push(def);
  66         }
  67     }
  68
  69     fn add_ext(&mut self, scope: Mark, ident: ast::Ident, ext: Rc<SyntaxExtension>) {
  70         if let NormalTT(..) = *ext {
  71             self.macro_names.insert(ident.name);
  72         }
  73
  74         let mut module = self.expansion_data[&scope.as_u32()].module.clone();
  75         while module.macros_escape {
  76             module = module.parent.clone().unwrap();
  77         }
  78         module.macros.borrow_mut().insert(ident.name, ext);
  79     }
  80
  81     fn add_expansions_at_stmt(&mut self, id: ast::NodeId, macros: Vec<Mark>) {
  82         self.macros_at_scope.insert(id, macros);
  83     }
  84
  85     fn find_attr_invoc(&mut self, attrs: &mut Vec<ast::Attribute>) -> Option<ast::Attribute> {
  86         for i in 0..attrs.len() {
  87             let name = intern(&attrs[i].name());
  88             match self.expansion_data[&0].module.macros.borrow().get(&name) {
  89                 Some(ext) => match **ext {
  90                     MultiModifier(..) | MultiDecorator(..) | SyntaxExtension::AttrProcMacro(..) => {
  91                         return Some(attrs.remove(i))
  92                     }
  93                     _ => {}
  94                 },
  95                 None => {}
  96             }
  97         }
  98         None
  99     }
 100
 101     fn resolve_invoc(&mut self, scope: Mark, invoc: &Invocation) -> Option<Rc<SyntaxExtension>> {
 102         let (name, span) = match invoc.kind {
 103             InvocationKind::Bang { ref mac, .. } => {
 104                 let path = &mac.node.path;
 105                 if path.segments.len() > 1 || path.global ||
 106                    !path.segments[0].parameters.is_empty() {
 107                     self.session.span_err(path.span,
 108                                           "expected macro name without module separators");
 109                     return None;
 110                 }
 111                 (path.segments[0].identifier.name, path.span)
 112             }
 113             InvocationKind::Attr { ref attr, .. } => (intern(&*attr.name()), attr.span),
 114         };
 115
 116         let mut module = self.expansion_data[&scope.as_u32()].module.clone();
 117         loop {
 118             if let Some(ext) = module.macros.borrow().get(&name) {
 119                 return Some(ext.clone());
 120             }
 121             match module.parent.clone() {
 122                 Some(parent) => module = parent,
 123                 None => break,
 124             }
 125         }
 126
 127         let mut err =
 128             self.session.struct_span_err(span, &format!("macro undefined: '{}!'", name));
 129         self.suggest_macro_name(&name.as_str(), &mut err);
 130         err.emit();
 131         None
 132     }
 133
 134     fn resolve_derive_mode(&mut self, ident: ast::Ident) -> Option<Rc<MultiItemModifier>> {
 135         self.derive_modes.get(&ident.name).cloned()
 136     }
 137 }
 138
 139 impl<'a> Resolver<'a> {
 140     fn suggest_macro_name(&mut self, name: &str, err: &mut DiagnosticBuilder<'a>) {
 141         if let Some(suggestion) = find_best_match_for_name(self.macro_names.iter(), name, None) {
 142             if suggestion != name {
 143                 err.help(&format!("did you mean `{}!`?", suggestion));
 144             } else {
 145                 err.help(&format!("have you added the `#[macro_use]` on the module/import?"));
 146             }
 147         }
 148     }
 149
 150     fn insert_custom_derive(&mut self, name: &str, ext: Rc<MultiItemModifier>, sp: Span) {
 151         if !self.session.features.borrow().rustc_macro {
 152             let sess = &self.session.parse_sess;
 153             let msg = "loading custom derive macro crates is experimentally supported";
 154             emit_feature_err(sess, "rustc_macro", sp, feature_gate::GateIssue::Language, msg);
 155         }
 156         if self.derive_modes.insert(token::intern(name), ext).is_some() {
 157             self.session.span_err(sp, &format!("cannot shadow existing derive mode `{}`", name));
 158         }
 159     }
 160 }
 161
 162 struct ExpansionVisitor<'b, 'a: 'b> {
 163     resolver: &'b mut Resolver<'a>,
 164     current_module: Rc<ModuleData>,
 165 }
 166
 167 impl<'a, 'b> ExpansionVisitor<'a, 'b> {
 168     fn visit_invoc(&mut self, id: ast::NodeId) {
 169         self.resolver.expansion_data.insert(id.as_u32(), ExpansionData {
 170             module: self.current_module.clone(),
 171         });
 172     }
 173
 174     // does this attribute list contain "macro_use"?
 175     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
 176         for attr in attrs {
 177             if attr.check_name("macro_escape") {
 178                 let msg = "macro_escape is a deprecated synonym for macro_use";
 179                 let mut err = self.resolver.session.struct_span_warn(attr.span, msg);
 180                 if let ast::AttrStyle::Inner = attr.node.style {
 181                     err.help("consider an outer attribute, #[macro_use] mod ...").emit();
 182                 } else {
 183                     err.emit();
 184                 }
 185             } else if !attr.check_name("macro_use") {
 186                 continue;
 187             }
 188
 189             if !attr.is_word() {
 190                 self.resolver.session.span_err(attr.span,
 191                                                "arguments to macro_use are not allowed here");
 192             }
 193             return true;
 194         }
 195
 196         false
 197     }
 198 }
 199
 200 macro_rules! method {
 201     ($visit:ident: $ty:ty, $invoc:path, $walk:ident) => {
 202         fn $visit(&mut self, node: &$ty) {
 203             match node.node {
 204                 $invoc(..) => self.visit_invoc(node.id),
 205                 _ => visit::$walk(self, node),
 206             }
 207         }
 208     }
 209 }
 210
 211 impl<'a, 'b> Visitor for ExpansionVisitor<'a, 'b>  {
 212     method!(visit_trait_item: ast::TraitItem, ast::TraitItemKind::Macro, walk_trait_item);
 213     method!(visit_impl_item:  ast::ImplItem,  ast::ImplItemKind::Macro,  walk_impl_item);
 214     method!(visit_stmt:       ast::Stmt,      ast::StmtKind::Mac,        walk_stmt);
 215     method!(visit_expr:       ast::Expr,      ast::ExprKind::Mac,        walk_expr);
 216     method!(visit_pat:        ast::Pat,       ast::PatKind::Mac,         walk_pat);
 217     method!(visit_ty:         ast::Ty,        ast::TyKind::Mac,          walk_ty);
 218
 219     fn visit_item(&mut self, item: &ast::Item) {
 220         match item.node {
 221             ast::ItemKind::Mac(..) if item.id == ast::DUMMY_NODE_ID => {} // Scope placeholder
 222             ast::ItemKind::Mac(..) => self.visit_invoc(item.id),
 223             ast::ItemKind::Mod(..) => {
 224                 let module_data = ModuleData {
 225                     parent: Some(self.current_module.clone()),
 226                     macros: RefCell::new(FnvHashMap()),
 227                     macros_escape: self.contains_macro_use(&item.attrs),
 228                 };
 229                 let orig_module = mem::replace(&mut self.current_module, Rc::new(module_data));
 230                 visit::walk_item(self, item);
 231                 self.current_module = orig_module;
 232             }
 233             ast::ItemKind::ExternCrate(..) => {
 234                 // We need to error on `#[macro_use] extern crate` when it isn't at the
 235                 // crate root, because `$crate` won't work properly.
 236                 // FIXME(jseyfried): This will be nicer once `ModuleData` is merged with `ModuleS`.
 237                 let is_crate_root = self.current_module.parent.as_ref().unwrap().parent.is_none();
 238                 for def in self.resolver.crate_loader.load_macros(item, is_crate_root) {
 239                     match def {
 240                         LoadedMacro::Def(def) => self.resolver.add_macro(Mark::root(), def),
 241                         LoadedMacro::CustomDerive(name, ext) => {
 242                             self.resolver.insert_custom_derive(&name, ext, item.span);
 243                         }
 244                     }
 245                 }
 246                 visit::walk_item(self, item);
 247             }
 248             _ => visit::walk_item(self, item),
 249         }
 250     }
 251
 252     fn visit_block(&mut self, block: &ast::Block) {
 253         let module_data = ModuleData {
 254             parent: Some(self.current_module.clone()),
 255             macros: RefCell::new(FnvHashMap()),
 256             macros_escape: false,
 257         };
 258         let orig_module = mem::replace(&mut self.current_module, Rc::new(module_data));
 259         visit::walk_block(self, block);
 260         self.current_module = orig_module;
 261     }
 262 }