1 files changed, 282 insertions, 99 deletions

diff --git a/crates/ra_hir/src/semantics.rs b/crates/ra_hir/src/semantics.rs
index 6a49c424a..6f3b3dc9a 100644
--- a/crates/ra_hir/src/semantics.rs
+++ b/crates/ra_hir/src/semantics.rs
@@ -6,7 +6,7 @@ use std::{cell::RefCell, fmt, iter::successors};
 
 use hir_def::{
     resolver::{self, HasResolver, Resolver},
-    AsMacroCall, TraitId, VariantId,
+    AsMacroCall, FunctionId, TraitId, VariantId,
 };
 use hir_expand::{diagnostics::AstDiagnostic, hygiene::Hygiene, ExpansionInfo};
 use hir_ty::associated_type_shorthand_candidates;
@@ -24,8 +24,8 @@ use crate::{
     diagnostics::Diagnostic,
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, resolve_hir_path_qualifier, SourceAnalyzer},
-    AssocItem, Field, Function, HirFileId, ImplDef, InFile, Local, MacroDef, Module, ModuleDef,
-    Name, Origin, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam,
+    AssocItem, Callable, Field, Function, HirFileId, ImplDef, InFile, Local, MacroDef, Module,
+    ModuleDef, Name, Origin, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam, VariantDef,
 };
 use resolver::TypeNs;
 
@@ -83,7 +83,13 @@ impl PathResolution {
 /// Primary API to get semantic information, like types, from syntax trees.
 pub struct Semantics<'db, DB> {
     pub db: &'db DB,
+    imp: SemanticsImpl<'db>,
+}
+
+pub struct SemanticsImpl<'db> {
+    pub db: &'db dyn HirDatabase,
     s2d_cache: RefCell<SourceToDefCache>,
+    expansion_info_cache: RefCell<FxHashMap<HirFileId, Option<ExpansionInfo>>>,
     cache: RefCell<FxHashMap<SyntaxNode, HirFileId>>,
 }
 
@@ -95,23 +101,199 @@ impl<DB> fmt::Debug for Semantics<'_, DB> {
 
 impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn new(db: &DB) -> Semantics<DB> {
-        Semantics { db, s2d_cache: Default::default(), cache: Default::default() }
+        let impl_ = SemanticsImpl::new(db);
+        Semantics { db, imp: impl_ }
     }
 
     pub fn parse(&self, file_id: FileId) -> ast::SourceFile {
-        let tree = self.db.parse(file_id).tree();
-        self.cache(tree.syntax().clone(), file_id.into());
-        tree
+        self.imp.parse(file_id)
     }
 
     pub fn ast<T: AstDiagnostic + Diagnostic>(&self, d: &T) -> <T as AstDiagnostic>::AST {
         let file_id = d.source().file_id;
         let root = self.db.parse_or_expand(file_id).unwrap();
-        self.cache(root, file_id);
-        d.ast(self.db)
+        self.imp.cache(root, file_id);
+        d.ast(self.db.upcast())
     }
 
     pub fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+        self.imp.expand(macro_call)
+    }
+
+    pub fn expand_hypothetical(
+        &self,
+        actual_macro_call: &ast::MacroCall,
+        hypothetical_args: &ast::TokenTree,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        self.imp.expand_hypothetical(actual_macro_call, hypothetical_args, token_to_map)
+    }
+
+    pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
+        self.imp.descend_into_macros(token)
+    }
+
+    pub fn descend_node_at_offset<N: ast::AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<N> {
+        self.imp.descend_node_at_offset(node, offset).find_map(N::cast)
+    }
+
+    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
+        self.imp.original_range(node)
+    }
+
+    pub fn diagnostics_range(&self, diagnostics: &dyn Diagnostic) -> FileRange {
+        self.imp.diagnostics_range(diagnostics)
+    }
+
+    pub fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
+        self.imp.ancestors_with_macros(node)
+    }
+
+    pub fn ancestors_at_offset_with_macros(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        self.imp.ancestors_at_offset_with_macros(node, offset)
+    }
+
+    /// Find a AstNode by offset inside SyntaxNode, if it is inside *Macrofile*,
+    /// search up until it is of the target AstNode type
+    pub fn find_node_at_offset_with_macros<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<N> {
+        self.imp.ancestors_at_offset_with_macros(node, offset).find_map(N::cast)
+    }
+
+    /// Find a AstNode by offset inside SyntaxNode, if it is inside *MacroCall*,
+    /// descend it and find again
+    pub fn find_node_at_offset_with_descend<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextSize,
+    ) -> Option<N> {
+        if let Some(it) = find_node_at_offset(&node, offset) {
+            return Some(it);
+        }
+
+        self.imp.descend_node_at_offset(node, offset).find_map(N::cast)
+    }
+
+    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
+        self.imp.type_of_expr(expr)
+    }
+
+    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<Type> {
+        self.imp.type_of_pat(pat)
+    }
+
+    pub fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
+        self.imp.type_of_self(param)
+    }
+
+    pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
+        self.imp.resolve_method_call(call).map(Function::from)
+    }
+
+    pub fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
+        self.imp.resolve_method_call_as_callable(call)
+    }
+
+    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
+        self.imp.resolve_field(field)
+    }
+
+    pub fn resolve_record_field(
+        &self,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>)> {
+        self.imp.resolve_record_field(field)
+    }
+
+    pub fn resolve_record_field_pat(&self, field: &ast::RecordFieldPat) -> Option<Field> {
+        self.imp.resolve_record_field_pat(field)
+    }
+
+    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<MacroDef> {
+        self.imp.resolve_macro_call(macro_call)
+    }
+
+    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+        self.imp.resolve_path(path)
+    }
+
+    pub fn resolve_variant(&self, record_lit: ast::RecordExpr) -> Option<VariantDef> {
+        self.imp.resolve_variant(record_lit).map(VariantDef::from)
+    }
+
+    pub fn lower_path(&self, path: &ast::Path) -> Option<Path> {
+        self.imp.lower_path(path)
+    }
+
+    pub fn resolve_bind_pat_to_const(&self, pat: &ast::BindPat) -> Option<ModuleDef> {
+        self.imp.resolve_bind_pat_to_const(pat)
+    }
+
+    // FIXME: use this instead?
+    // pub fn resolve_name_ref(&self, name_ref: &ast::NameRef) -> Option<???>;
+
+    pub fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
+        self.imp.record_literal_missing_fields(literal)
+    }
+
+    pub fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
+        self.imp.record_pattern_missing_fields(pattern)
+    }
+
+    pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
+        let src = self.imp.find_file(src.syntax().clone()).with_value(src).cloned();
+        T::to_def(&self.imp, src)
+    }
+
+    pub fn to_module_def(&self, file: FileId) -> Option<Module> {
+        self.imp.to_module_def(file)
+    }
+
+    pub fn scope(&self, node: &SyntaxNode) -> SemanticsScope<'db> {
+        self.imp.scope(node)
+    }
+
+    pub fn scope_at_offset(&self, node: &SyntaxNode, offset: TextSize) -> SemanticsScope<'db> {
+        self.imp.scope_at_offset(node, offset)
+    }
+
+    pub fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db> {
+        self.imp.scope_for_def(def)
+    }
+
+    pub fn assert_contains_node(&self, node: &SyntaxNode) {
+        self.imp.assert_contains_node(node)
+    }
+}
+
+impl<'db> SemanticsImpl<'db> {
+    fn new(db: &'db dyn HirDatabase) -> Self {
+        SemanticsImpl {
+            db,
+            s2d_cache: Default::default(),
+            cache: Default::default(),
+            expansion_info_cache: Default::default(),
+        }
+    }
+
+    fn parse(&self, file_id: FileId) -> ast::SourceFile {
+        let tree = self.db.parse(file_id).tree();
+        self.cache(tree.syntax().clone(), file_id.into());
+        tree
+    }
+
+    fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
         let macro_call = self.find_file(macro_call.syntax().clone()).with_value(macro_call);
         let sa = self.analyze2(macro_call.map(|it| it.syntax()), None);
         let file_id = sa.expand(self.db, macro_call)?;
@@ -120,7 +302,7 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         Some(node)
     }
 
-    pub fn expand_hypothetical(
+    fn expand_hypothetical(
         &self,
         actual_macro_call: &ast::MacroCall,
         hypothetical_args: &ast::TokenTree,
@@ -130,24 +312,38 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
             self.find_file(actual_macro_call.syntax().clone()).with_value(actual_macro_call);
         let sa = self.analyze2(macro_call.map(|it| it.syntax()), None);
         let krate = sa.resolver.krate()?;
-        let macro_call_id = macro_call
-            .as_call_id(self.db, krate, |path| sa.resolver.resolve_path_as_macro(self.db, &path))?;
-        hir_expand::db::expand_hypothetical(self.db, macro_call_id, hypothetical_args, token_to_map)
-    }
-
-    pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
+        let macro_call_id = macro_call.as_call_id(self.db.upcast(), krate, |path| {
+            sa.resolver.resolve_path_as_macro(self.db.upcast(), &path)
+        })?;
+        hir_expand::db::expand_hypothetical(
+            self.db.upcast(),
+            macro_call_id,
+            hypothetical_args,
+            token_to_map,
+        )
+    }
+
+    fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
+        let _p = profile("descend_into_macros");
         let parent = token.parent();
         let parent = self.find_file(parent);
         let sa = self.analyze2(parent.as_ref(), None);
 
         let token = successors(Some(parent.with_value(token)), |token| {
+            self.db.check_canceled();
             let macro_call = token.value.ancestors().find_map(ast::MacroCall::cast)?;
             let tt = macro_call.token_tree()?;
             if !tt.syntax().text_range().contains_range(token.value.text_range()) {
                 return None;
             }
             let file_id = sa.expand(self.db, token.with_value(&macro_call))?;
-            let token = file_id.expansion_info(self.db)?.map_token_down(token.as_ref())?;
+            let token = self
+                .expansion_info_cache
+                .borrow_mut()
+                .entry(file_id)
+                .or_insert_with(|| file_id.expansion_info(self.db.upcast()))
+                .as_ref()?
+                .map_token_down(token.as_ref())?;
 
             self.cache(find_root(&token.value.parent()), token.file_id);
 
@@ -159,35 +355,36 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         token.value
     }
 
-    pub fn descend_node_at_offset<N: ast::AstNode>(
+    fn descend_node_at_offset(
         &self,
         node: &SyntaxNode,
         offset: TextSize,
-    ) -> Option<N> {
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
         // Handle macro token cases
         node.token_at_offset(offset)
             .map(|token| self.descend_into_macros(token))
-            .find_map(|it| self.ancestors_with_macros(it.parent()).find_map(N::cast))
+            .map(|it| self.ancestors_with_macros(it.parent()))
+            .flatten()
     }
 
-    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
+    fn original_range(&self, node: &SyntaxNode) -> FileRange {
         let node = self.find_file(node.clone());
         original_range(self.db, node.as_ref())
     }
 
-    pub fn diagnostics_range(&self, diagnostics: &dyn Diagnostic) -> FileRange {
+    fn diagnostics_range(&self, diagnostics: &dyn Diagnostic) -> FileRange {
         let src = diagnostics.source();
         let root = self.db.parse_or_expand(src.file_id).unwrap();
         let node = src.value.to_node(&root);
         original_range(self.db, src.with_value(&node))
     }
 
-    pub fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
+    fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
         let node = self.find_file(node);
-        node.ancestors_with_macros(self.db).map(|it| it.value)
+        node.ancestors_with_macros(self.db.upcast()).map(|it| it.value)
     }
 
-    pub fn ancestors_at_offset_with_macros(
+    fn ancestors_at_offset_with_macros(
         &self,
         node: &SyntaxNode,
         offset: TextSize,
@@ -197,120 +394,104 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
             .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
     }
 
-    /// Find a AstNode by offset inside SyntaxNode, if it is inside *Macrofile*,
-    /// search up until it is of the target AstNode type
-    pub fn find_node_at_offset_with_macros<N: AstNode>(
-        &self,
-        node: &SyntaxNode,
-        offset: TextSize,
-    ) -> Option<N> {
-        self.ancestors_at_offset_with_macros(node, offset).find_map(N::cast)
+    fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
+        self.analyze(expr.syntax()).type_of_expr(self.db, &expr)
     }
 
-    /// Find a AstNode by offset inside SyntaxNode, if it is inside *MacroCall*,
-    /// descend it and find again
-    pub fn find_node_at_offset_with_descend<N: AstNode>(
-        &self,
-        node: &SyntaxNode,
-        offset: TextSize,
-    ) -> Option<N> {
-        if let Some(it) = find_node_at_offset(&node, offset) {
-            return Some(it);
-        }
-        self.descend_node_at_offset(&node, offset)
+    fn type_of_pat(&self, pat: &ast::Pat) -> Option<Type> {
+        self.analyze(pat.syntax()).type_of_pat(self.db, &pat)
     }
 
-    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
-        self.analyze(expr.syntax()).type_of(self.db, &expr)
+    fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
+        self.analyze(param.syntax()).type_of_self(self.db, &param)
     }
 
-    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<Type> {
-        self.analyze(pat.syntax()).type_of_pat(self.db, &pat)
+    fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
+        self.analyze(call.syntax()).resolve_method_call(self.db, call)
     }
 
-    pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
-        self.analyze(call.syntax()).resolve_method_call(self.db, call)
+    fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
+        // FIXME: this erases Substs
+        let func = self.resolve_method_call(call)?;
+        let ty = self.db.value_ty(func.into());
+        let resolver = self.analyze(call.syntax()).resolver;
+        let ty = Type::new_with_resolver(self.db, &resolver, ty.value)?;
+        let mut res = ty.as_callable(self.db)?;
+        res.is_bound_method = true;
+        Some(res)
     }
 
-    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
+    fn resolve_field(&self, field: &ast::FieldExpr) -> Option<Field> {
         self.analyze(field.syntax()).resolve_field(self.db, field)
     }
 
-    pub fn resolve_record_field(&self, field: &ast::RecordField) -> Option<(Field, Option<Local>)> {
+    fn resolve_record_field(&self, field: &ast::RecordExprField) -> Option<(Field, Option<Local>)> {
         self.analyze(field.syntax()).resolve_record_field(self.db, field)
     }
 
-    pub fn resolve_record_field_pat(&self, field: &ast::RecordFieldPat) -> Option<Field> {
+    fn resolve_record_field_pat(&self, field: &ast::RecordFieldPat) -> Option<Field> {
         self.analyze(field.syntax()).resolve_record_field_pat(self.db, field)
     }
 
-    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<MacroDef> {
+    fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<MacroDef> {
         let sa = self.analyze(macro_call.syntax());
         let macro_call = self.find_file(macro_call.syntax().clone()).with_value(macro_call);
         sa.resolve_macro_call(self.db, macro_call)
     }
 
-    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+    fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
         self.analyze(path.syntax()).resolve_path(self.db, path)
     }
 
-    pub fn resolve_variant(&self, record_lit: ast::RecordLit) -> Option<VariantId> {
+    fn resolve_variant(&self, record_lit: ast::RecordExpr) -> Option<VariantId> {
         self.analyze(record_lit.syntax()).resolve_variant(self.db, record_lit)
     }
 
-    pub fn lower_path(&self, path: &ast::Path) -> Option<Path> {
+    fn lower_path(&self, path: &ast::Path) -> Option<Path> {
         let src = self.find_file(path.syntax().clone());
         Path::from_src(path.clone(), &Hygiene::new(self.db.upcast(), src.file_id.into()))
     }
 
-    pub fn resolve_bind_pat_to_const(&self, pat: &ast::BindPat) -> Option<ModuleDef> {
+    fn resolve_bind_pat_to_const(&self, pat: &ast::BindPat) -> Option<ModuleDef> {
         self.analyze(pat.syntax()).resolve_bind_pat_to_const(self.db, pat)
     }
 
-    // FIXME: use this instead?
-    // pub fn resolve_name_ref(&self, name_ref: &ast::NameRef) -> Option<???>;
-
-    pub fn record_literal_missing_fields(&self, literal: &ast::RecordLit) -> Vec<(Field, Type)> {
+    fn record_literal_missing_fields(&self, literal: &ast::RecordExpr) -> Vec<(Field, Type)> {
         self.analyze(literal.syntax())
             .record_literal_missing_fields(self.db, literal)
             .unwrap_or_default()
     }
 
-    pub fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
+    fn record_pattern_missing_fields(&self, pattern: &ast::RecordPat) -> Vec<(Field, Type)> {
         self.analyze(pattern.syntax())
             .record_pattern_missing_fields(self.db, pattern)
             .unwrap_or_default()
     }
 
-    pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
-        let src = self.find_file(src.syntax().clone()).with_value(src).cloned();
-        T::to_def(self, src)
-    }
-
     fn with_ctx<F: FnOnce(&mut SourceToDefCtx) -> T, T>(&self, f: F) -> T {
         let mut cache = self.s2d_cache.borrow_mut();
         let mut ctx = SourceToDefCtx { db: self.db, cache: &mut *cache };
         f(&mut ctx)
     }
 
-    pub fn to_module_def(&self, file: FileId) -> Option<Module> {
+    fn to_module_def(&self, file: FileId) -> Option<Module> {
         self.with_ctx(|ctx| ctx.file_to_def(file)).map(Module::from)
     }
 
-    pub fn scope(&self, node: &SyntaxNode) -> SemanticsScope<'db, DB> {
+    fn scope(&self, node: &SyntaxNode) -> SemanticsScope<'db> {
         let node = self.find_file(node.clone());
         let resolver = self.analyze2(node.as_ref(), None).resolver;
         SemanticsScope { db: self.db, resolver }
     }
 
-    pub fn scope_at_offset(&self, node: &SyntaxNode, offset: TextSize) -> SemanticsScope<'db, DB> {
+    fn scope_at_offset(&self, node: &SyntaxNode, offset: TextSize) -> SemanticsScope<'db> {
         let node = self.find_file(node.clone());
         let resolver = self.analyze2(node.as_ref(), Some(offset)).resolver;
         SemanticsScope { db: self.db, resolver }
     }
 
-    pub fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db, DB> {
-        let resolver = def.id.resolver(self.db);
+    fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db> {
+        let resolver = def.id.resolver(self.db.upcast());
         SemanticsScope { db: self.db, resolver }
     }
 
@@ -331,12 +512,13 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
             ChildContainer::DefWithBodyId(def) => {
                 return SourceAnalyzer::new_for_body(self.db, def, src, offset)
             }
-            ChildContainer::TraitId(it) => it.resolver(self.db),
-            ChildContainer::ImplId(it) => it.resolver(self.db),
-            ChildContainer::ModuleId(it) => it.resolver(self.db),
-            ChildContainer::EnumId(it) => it.resolver(self.db),
-            ChildContainer::VariantId(it) => it.resolver(self.db),
-            ChildContainer::GenericDefId(it) => it.resolver(self.db),
+            ChildContainer::TraitId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::ImplId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::ModuleId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::EnumId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::VariantId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::TypeAliasId(it) => it.resolver(self.db.upcast()),
+            ChildContainer::GenericDefId(it) => it.resolver(self.db.upcast()),
         };
         SourceAnalyzer::new_for_resolver(resolver, src)
     }
@@ -348,7 +530,7 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         assert!(prev == None || prev == Some(file_id))
     }
 
-    pub fn assert_contains_node(&self, node: &SyntaxNode) {
+    fn assert_contains_node(&self, node: &SyntaxNode) {
         self.find_file(node.clone());
     }
 
@@ -382,14 +564,14 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
 pub trait ToDef: AstNode + Clone {
     type Def;
 
-    fn to_def<DB: HirDatabase>(sema: &Semantics<DB>, src: InFile<Self>) -> Option<Self::Def>;
+    fn to_def(sema: &SemanticsImpl, src: InFile<Self>) -> Option<Self::Def>;
 }
 
 macro_rules! to_def_impls {
     ($(($def:path, $ast:path, $meth:ident)),* ,) => {$(
         impl ToDef for $ast {
             type Def = $def;
-            fn to_def<DB: HirDatabase>(sema: &Semantics<DB>, src: InFile<Self>) -> Option<Self::Def> {
+            fn to_def(sema: &SemanticsImpl, src: InFile<Self>) -> Option<Self::Def> {
                 sema.with_ctx(|ctx| ctx.$meth(src)).map(<$def>::from)
             }
         }
@@ -398,18 +580,18 @@ macro_rules! to_def_impls {
 
 to_def_impls![
     (crate::Module, ast::Module, module_to_def),
-    (crate::Struct, ast::StructDef, struct_to_def),
-    (crate::Enum, ast::EnumDef, enum_to_def),
-    (crate::Union, ast::UnionDef, union_to_def),
-    (crate::Trait, ast::TraitDef, trait_to_def),
-    (crate::ImplDef, ast::ImplDef, impl_to_def),
-    (crate::TypeAlias, ast::TypeAliasDef, type_alias_to_def),
-    (crate::Const, ast::ConstDef, const_to_def),
-    (crate::Static, ast::StaticDef, static_to_def),
-    (crate::Function, ast::FnDef, fn_to_def),
-    (crate::Field, ast::RecordFieldDef, record_field_to_def),
-    (crate::Field, ast::TupleFieldDef, tuple_field_to_def),
-    (crate::EnumVariant, ast::EnumVariant, enum_variant_to_def),
+    (crate::Struct, ast::Struct, struct_to_def),
+    (crate::Enum, ast::Enum, enum_to_def),
+    (crate::Union, ast::Union, union_to_def),
+    (crate::Trait, ast::Trait, trait_to_def),
+    (crate::ImplDef, ast::Impl, impl_to_def),
+    (crate::TypeAlias, ast::TypeAlias, type_alias_to_def),
+    (crate::Const, ast::Const, const_to_def),
+    (crate::Static, ast::Static, static_to_def),
+    (crate::Function, ast::Fn, fn_to_def),
+    (crate::Field, ast::RecordField, record_field_to_def),
+    (crate::Field, ast::TupleField, tuple_field_to_def),
+    (crate::EnumVariant, ast::Variant, enum_variant_to_def),
     (crate::TypeParam, ast::TypeParam, type_param_to_def),
     (crate::MacroDef, ast::MacroCall, macro_call_to_def), // this one is dubious, not all calls are macros
     (crate::Local, ast::BindPat, bind_pat_to_def),
@@ -419,12 +601,13 @@ fn find_root(node: &SyntaxNode) -> SyntaxNode {
     node.ancestors().last().unwrap()
 }
 
-pub struct SemanticsScope<'a, DB> {
-    pub db: &'a DB,
+#[derive(Debug)]
+pub struct SemanticsScope<'a> {
+    pub db: &'a dyn HirDatabase,
     resolver: Resolver,
 }
 
-impl<'a, DB: HirDatabase> SemanticsScope<'a, DB> {
+impl<'a> SemanticsScope<'a> {
     pub fn module(&self) -> Option<Module> {
         Some(Module { id: self.resolver.module()? })
     }
@@ -433,13 +616,13 @@ impl<'a, DB: HirDatabase> SemanticsScope<'a, DB> {
     // FIXME: rename to visible_traits to not repeat scope?
     pub fn traits_in_scope(&self) -> FxHashSet<TraitId> {
         let resolver = &self.resolver;
-        resolver.traits_in_scope(self.db)
+        resolver.traits_in_scope(self.db.upcast())
     }
 
     pub fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
         let resolver = &self.resolver;
 
-        resolver.process_all_names(self.db, &mut |name, def| {
+        resolver.process_all_names(self.db.upcast(), &mut |name, def| {
             let def = match def {
                 resolver::ScopeDef::PerNs(it) => {
                     let items = ScopeDef::all_items(it);