compiler/rustc_resolve/src/def_collector.rs

   1 use crate::{ImplTraitContext, Resolver};
   2 use rustc_ast::visit::{self, FnKind};
   3 use rustc_ast::walk_list;
   4 use rustc_ast::*;
   5 use rustc_ast_lowering::ResolverAstLowering;
   6 use rustc_expand::expand::AstFragment;
   7 use rustc_hir::def_id::LocalDefId;
   8 use rustc_hir::definitions::*;
   9 use rustc_span::hygiene::LocalExpnId;
  10 use rustc_span::symbol::{kw, sym};
  11 use rustc_span::Span;
  12 use tracing::debug;
  13
  14 crate fn collect_definitions(
  15     resolver: &mut Resolver<'_>,
  16     fragment: &AstFragment,
  17     expansion: LocalExpnId,
  18 ) {
  19     let (parent_def, impl_trait_context) = resolver.invocation_parents[&expansion];
  20     fragment.visit_with(&mut DefCollector { resolver, parent_def, expansion, impl_trait_context });
  21 }
  22
  23 /// Creates `DefId`s for nodes in the AST.
  24 struct DefCollector<'a, 'b> {
  25     resolver: &'a mut Resolver<'b>,
  26     parent_def: LocalDefId,
  27     impl_trait_context: ImplTraitContext,
  28     expansion: LocalExpnId,
  29 }
  30
  31 impl<'a, 'b> DefCollector<'a, 'b> {
  32     fn create_def(&mut self, node_id: NodeId, data: DefPathData, span: Span) -> LocalDefId {
  33         let parent_def = self.parent_def;
  34         debug!("create_def(node_id={:?}, data={:?}, parent_def={:?})", node_id, data, parent_def);
  35         self.resolver.create_def(parent_def, node_id, data, self.expansion.to_expn_id(), span)
  36     }
  37
  38     fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: LocalDefId, f: F) {
  39         let orig_parent_def = std::mem::replace(&mut self.parent_def, parent_def);
  40         f(self);
  41         self.parent_def = orig_parent_def;
  42     }
  43
  44     fn with_impl_trait<F: FnOnce(&mut Self)>(
  45         &mut self,
  46         impl_trait_context: ImplTraitContext,
  47         f: F,
  48     ) {
  49         let orig_itc = std::mem::replace(&mut self.impl_trait_context, impl_trait_context);
  50         f(self);
  51         self.impl_trait_context = orig_itc;
  52     }
  53
  54     fn collect_field(&mut self, field: &'a FieldDef, index: Option<usize>) {
  55         let index = |this: &Self| {
  56             index.unwrap_or_else(|| {
  57                 let node_id = NodeId::placeholder_from_expn_id(this.expansion);
  58                 this.resolver.placeholder_field_indices[&node_id]
  59             })
  60         };
  61
  62         if field.is_placeholder {
  63             let old_index = self.resolver.placeholder_field_indices.insert(field.id, index(self));
  64             assert!(old_index.is_none(), "placeholder field index is reset for a node ID");
  65             self.visit_macro_invoc(field.id);
  66         } else {
  67             let name = field.ident.map_or_else(|| sym::integer(index(self)), |ident| ident.name);
  68             let def = self.create_def(field.id, DefPathData::ValueNs(name), field.span);
  69             self.with_parent(def, |this| visit::walk_field_def(this, field));
  70         }
  71     }
  72
  73     fn visit_macro_invoc(&mut self, id: NodeId) {
  74         let id = id.placeholder_to_expn_id();
  75         let old_parent =
  76             self.resolver.invocation_parents.insert(id, (self.parent_def, self.impl_trait_context));
  77         assert!(old_parent.is_none(), "parent `LocalDefId` is reset for an invocation");
  78     }
  79 }
  80
  81 impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
  82     fn visit_item(&mut self, i: &'a Item) {
  83         debug!("visit_item: {:?}", i);
  84
  85         // Pick the def data. This need not be unique, but the more
  86         // information we encapsulate into, the better
  87         let def_data = match &i.kind {
  88             ItemKind::Impl { .. } => DefPathData::Impl,
  89             ItemKind::Mod(..) if i.ident.name == kw::Empty => {
  90                 // Fake crate root item from expand.
  91                 return visit::walk_item(self, i);
  92             }
  93             ItemKind::Mod(..)
  94             | ItemKind::Trait(..)
  95             | ItemKind::TraitAlias(..)
  96             | ItemKind::Enum(..)
  97             | ItemKind::Struct(..)
  98             | ItemKind::Union(..)
  99             | ItemKind::ExternCrate(..)
 100             | ItemKind::ForeignMod(..)
 101             | ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
 102             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) => {
 103                 DefPathData::ValueNs(i.ident.name)
 104             }
 105             ItemKind::MacroDef(..) => DefPathData::MacroNs(i.ident.name),
 106             ItemKind::MacCall(..) => {
 107                 visit::walk_item(self, i);
 108                 return self.visit_macro_invoc(i.id);
 109             }
 110             ItemKind::GlobalAsm(..) => DefPathData::Misc,
 111             ItemKind::Use(..) => {
 112                 return visit::walk_item(self, i);
 113             }
 114         };
 115         let def = self.create_def(i.id, def_data, i.span);
 116
 117         self.with_parent(def, |this| {
 118             this.with_impl_trait(ImplTraitContext::Existential, |this| {
 119                 match i.kind {
 120                     ItemKind::Struct(ref struct_def, _) | ItemKind::Union(ref struct_def, _) => {
 121                         // If this is a unit or tuple-like struct, register the constructor.
 122                         if let Some(ctor_hir_id) = struct_def.ctor_id() {
 123                             this.create_def(ctor_hir_id, DefPathData::Ctor, i.span);
 124                         }
 125                     }
 126                     _ => {}
 127                 }
 128                 visit::walk_item(this, i);
 129             })
 130         });
 131     }
 132
 133     fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
 134         if let FnKind::Fn(_, _, sig, _, body) = fn_kind {
 135             if let Async::Yes { closure_id, return_impl_trait_id, .. } = sig.header.asyncness {
 136                 let return_impl_trait_id =
 137                     self.create_def(return_impl_trait_id, DefPathData::ImplTrait, span);
 138
 139                 // For async functions, we need to create their inner defs inside of a
 140                 // closure to match their desugared representation. Besides that,
 141                 // we must mirror everything that `visit::walk_fn` below does.
 142                 self.visit_fn_header(&sig.header);
 143                 for param in &sig.decl.inputs {
 144                     self.visit_param(param);
 145                 }
 146                 self.with_parent(return_impl_trait_id, |this| {
 147                     this.visit_fn_ret_ty(&sig.decl.output)
 148                 });
 149                 let closure_def = self.create_def(closure_id, DefPathData::ClosureExpr, span);
 150                 self.with_parent(closure_def, |this| walk_list!(this, visit_block, body));
 151                 return;
 152             }
 153         }
 154
 155         visit::walk_fn(self, fn_kind, span);
 156     }
 157
 158     fn visit_use_tree(&mut self, use_tree: &'a UseTree, id: NodeId, _nested: bool) {
 159         self.create_def(id, DefPathData::Misc, use_tree.span);
 160         match use_tree.kind {
 161             UseTreeKind::Simple(_, id1, id2) => {
 162                 self.create_def(id1, DefPathData::Misc, use_tree.prefix.span);
 163                 self.create_def(id2, DefPathData::Misc, use_tree.prefix.span);
 164             }
 165             UseTreeKind::Glob => (),
 166             UseTreeKind::Nested(..) => {}
 167         }
 168         visit::walk_use_tree(self, use_tree, id);
 169     }
 170
 171     fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
 172         if let ForeignItemKind::MacCall(_) = foreign_item.kind {
 173             return self.visit_macro_invoc(foreign_item.id);
 174         }
 175
 176         let def = self.create_def(
 177             foreign_item.id,
 178             DefPathData::ValueNs(foreign_item.ident.name),
 179             foreign_item.span,
 180         );
 181
 182         self.with_parent(def, |this| {
 183             visit::walk_foreign_item(this, foreign_item);
 184         });
 185     }
 186
 187     fn visit_variant(&mut self, v: &'a Variant) {
 188         if v.is_placeholder {
 189             return self.visit_macro_invoc(v.id);
 190         }
 191         let def = self.create_def(v.id, DefPathData::TypeNs(v.ident.name), v.span);
 192         self.with_parent(def, |this| {
 193             if let Some(ctor_hir_id) = v.data.ctor_id() {
 194                 this.create_def(ctor_hir_id, DefPathData::Ctor, v.span);
 195             }
 196             visit::walk_variant(this, v)
 197         });
 198     }
 199
 200     fn visit_variant_data(&mut self, data: &'a VariantData) {
 201         // The assumption here is that non-`cfg` macro expansion cannot change field indices.
 202         // It currently holds because only inert attributes are accepted on fields,
 203         // and every such attribute expands into a single field after it's resolved.
 204         for (index, field) in data.fields().iter().enumerate() {
 205             self.collect_field(field, Some(index));
 206         }
 207     }
 208
 209     fn visit_generic_param(&mut self, param: &'a GenericParam) {
 210         if param.is_placeholder {
 211             self.visit_macro_invoc(param.id);
 212             return;
 213         }
 214         let name = param.ident.name;
 215         let def_path_data = match param.kind {
 216             GenericParamKind::Lifetime { .. } => DefPathData::LifetimeNs(name),
 217             GenericParamKind::Type { .. } => DefPathData::TypeNs(name),
 218             GenericParamKind::Const { .. } => DefPathData::ValueNs(name),
 219         };
 220         self.create_def(param.id, def_path_data, param.ident.span);
 221
 222         // impl-Trait can happen inside generic parameters, like
 223         // ```
 224         // fn foo<U: Iterator<Item = impl Clone>>() {}
 225         // ```
 226         //
 227         // In that case, the impl-trait is lowered as an additional generic parameter.
 228         self.with_impl_trait(ImplTraitContext::Universal(self.parent_def), |this| {
 229             visit::walk_generic_param(this, param)
 230         });
 231     }
 232
 233     fn visit_assoc_item(&mut self, i: &'a AssocItem, ctxt: visit::AssocCtxt) {
 234         let def_data = match &i.kind {
 235             AssocItemKind::Fn(..) | AssocItemKind::Const(..) => DefPathData::ValueNs(i.ident.name),
 236             AssocItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
 237             AssocItemKind::MacCall(..) => return self.visit_macro_invoc(i.id),
 238         };
 239
 240         let def = self.create_def(i.id, def_data, i.span);
 241         self.with_parent(def, |this| visit::walk_assoc_item(this, i, ctxt));
 242     }
 243
 244     fn visit_pat(&mut self, pat: &'a Pat) {
 245         match pat.kind {
 246             PatKind::MacCall(..) => self.visit_macro_invoc(pat.id),
 247             _ => visit::walk_pat(self, pat),
 248         }
 249     }
 250
 251     fn visit_anon_const(&mut self, constant: &'a AnonConst) {
 252         let def = self.create_def(constant.id, DefPathData::AnonConst, constant.value.span);
 253         self.with_parent(def, |this| visit::walk_anon_const(this, constant));
 254     }
 255
 256     fn visit_expr(&mut self, expr: &'a Expr) {
 257         let parent_def = match expr.kind {
 258             ExprKind::MacCall(..) => return self.visit_macro_invoc(expr.id),
 259             ExprKind::Closure(_, asyncness, ..) => {
 260                 // Async closures desugar to closures inside of closures, so
 261                 // we must create two defs.
 262                 let closure_def = self.create_def(expr.id, DefPathData::ClosureExpr, expr.span);
 263                 match asyncness {
 264                     Async::Yes { closure_id, .. } => {
 265                         self.create_def(closure_id, DefPathData::ClosureExpr, expr.span)
 266                     }
 267                     Async::No => closure_def,
 268                 }
 269             }
 270             ExprKind::Async(_, async_id, _) => {
 271                 self.create_def(async_id, DefPathData::ClosureExpr, expr.span)
 272             }
 273             _ => self.parent_def,
 274         };
 275
 276         self.with_parent(parent_def, |this| visit::walk_expr(this, expr));
 277     }
 278
 279     fn visit_ty(&mut self, ty: &'a Ty) {
 280         match ty.kind {
 281             TyKind::MacCall(..) => self.visit_macro_invoc(ty.id),
 282             TyKind::ImplTrait(node_id, _) => {
 283                 let parent_def = match self.impl_trait_context {
 284                     ImplTraitContext::Universal(item_def) => self.resolver.create_def(
 285                         item_def,
 286                         node_id,
 287                         DefPathData::ImplTrait,
 288                         self.expansion.to_expn_id(),
 289                         ty.span,
 290                     ),
 291                     ImplTraitContext::Existential => {
 292                         self.create_def(node_id, DefPathData::ImplTrait, ty.span)
 293                     }
 294                 };
 295                 self.with_parent(parent_def, |this| visit::walk_ty(this, ty))
 296             }
 297             _ => visit::walk_ty(self, ty),
 298         }
 299     }
 300
 301     fn visit_stmt(&mut self, stmt: &'a Stmt) {
 302         match stmt.kind {
 303             StmtKind::MacCall(..) => self.visit_macro_invoc(stmt.id),
 304             _ => visit::walk_stmt(self, stmt),
 305         }
 306     }
 307
 308     fn visit_arm(&mut self, arm: &'a Arm) {
 309         if arm.is_placeholder { self.visit_macro_invoc(arm.id) } else { visit::walk_arm(self, arm) }
 310     }
 311
 312     fn visit_expr_field(&mut self, f: &'a ExprField) {
 313         if f.is_placeholder {
 314             self.visit_macro_invoc(f.id)
 315         } else {
 316             visit::walk_expr_field(self, f)
 317         }
 318     }
 319
 320     fn visit_pat_field(&mut self, fp: &'a PatField) {
 321         if fp.is_placeholder {
 322             self.visit_macro_invoc(fp.id)
 323         } else {
 324             visit::walk_pat_field(self, fp)
 325         }
 326     }
 327
 328     fn visit_param(&mut self, p: &'a Param) {
 329         if p.is_placeholder {
 330             self.visit_macro_invoc(p.id)
 331         } else {
 332             self.with_impl_trait(ImplTraitContext::Universal(self.parent_def), |this| {
 333                 visit::walk_param(this, p)
 334             })
 335         }
 336     }
 337
 338     // This method is called only when we are visiting an individual field
 339     // after expanding an attribute on it.
 340     fn visit_field_def(&mut self, field: &'a FieldDef) {
 341         self.collect_field(field, None);
 342     }
 343 }