19 files changed, 265 insertions, 127 deletions

diff --git a/crates/ra_hir_def/src/adt.rs b/crates/ra_hir_def/src/adt.rs
index 3666529b0..9ab829aab 100644
--- a/crates/ra_hir_def/src/adt.rs
+++ b/crates/ra_hir_def/src/adt.rs
@@ -5,13 +5,13 @@ use std::sync::Arc;
 use hir_expand::{
     either::Either,
     name::{AsName, Name},
-    Source,
+    InFile,
 };
 use ra_arena::{map::ArenaMap, Arena};
 use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
 
 use crate::{
-    db::DefDatabase, trace::Trace, type_ref::TypeRef, AstItemDef, EnumId, HasChildSource,
+    db::DefDatabase, src::HasChildSource, trace::Trace, type_ref::TypeRef, AstItemDef, EnumId,
     LocalEnumVariantId, LocalStructFieldId, StructId, UnionId, VariantId,
 };
 
@@ -88,7 +88,7 @@ impl EnumData {
 impl HasChildSource for EnumId {
     type ChildId = LocalEnumVariantId;
     type Value = ast::EnumVariant;
-    fn child_source(&self, db: &impl DefDatabase) -> Source<ArenaMap<Self::ChildId, Self::Value>> {
+    fn child_source(&self, db: &impl DefDatabase) -> InFile<ArenaMap<Self::ChildId, Self::Value>> {
         let src = self.source(db);
         let mut trace = Trace::new_for_map();
         lower_enum(&mut trace, &src.value);
@@ -145,7 +145,7 @@ impl HasChildSource for VariantId {
     type ChildId = LocalStructFieldId;
     type Value = Either<ast::TupleFieldDef, ast::RecordFieldDef>;
 
-    fn child_source(&self, db: &impl DefDatabase) -> Source<ArenaMap<Self::ChildId, Self::Value>> {
+    fn child_source(&self, db: &impl DefDatabase) -> InFile<ArenaMap<Self::ChildId, Self::Value>> {
         let src = match self {
             VariantId::EnumVariantId(it) => {
                 // I don't really like the fact that we call into parent source
diff --git a/crates/ra_hir_def/src/attr.rs b/crates/ra_hir_def/src/attr.rs
index fffb22201..bc7ade921 100644
--- a/crates/ra_hir_def/src/attr.rs
+++ b/crates/ra_hir_def/src/attr.rs
@@ -2,7 +2,7 @@
 
 use std::{ops, sync::Arc};
 
-use hir_expand::{either::Either, hygiene::Hygiene, AstId, Source};
+use hir_expand::{either::Either, hygiene::Hygiene, AstId, InFile};
 use mbe::ast_to_token_tree;
 use ra_syntax::{
     ast::{self, AstNode, AttrsOwner},
@@ -11,7 +11,8 @@ use ra_syntax::{
 use tt::Subtree;
 
 use crate::{
-    db::DefDatabase, path::Path, AdtId, AstItemDef, AttrDefId, HasChildSource, HasSource, Lookup,
+    db::DefDatabase, path::Path, src::HasChildSource, src::HasSource, AdtId, AstItemDef, AttrDefId,
+    Lookup,
 };
 
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
@@ -68,7 +69,7 @@ impl Attrs {
         }
     }
 
-    fn from_attrs_owner(db: &impl DefDatabase, owner: Source<&dyn AttrsOwner>) -> Attrs {
+    fn from_attrs_owner(db: &impl DefDatabase, owner: InFile<&dyn AttrsOwner>) -> Attrs {
         let hygiene = Hygiene::new(db, owner.file_id);
         Attrs::new(owner.value, &hygiene)
     }
@@ -157,7 +158,7 @@ where
     N: ast::AttrsOwner,
     D: DefDatabase,
 {
-    let src = Source::new(src.file_id(), src.to_node(db));
+    let src = InFile::new(src.file_id, src.to_node(db));
     Attrs::from_attrs_owner(db, src.as_ref().map(|it| it as &dyn AttrsOwner))
 }
 
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index a57a0176d..239f35229 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -6,7 +6,7 @@ pub mod scope;
 use std::{ops::Index, sync::Arc};
 
 use hir_expand::{
-    either::Either, hygiene::Hygiene, AstId, HirFileId, MacroDefId, MacroFileKind, Source,
+    either::Either, hygiene::Hygiene, AstId, HirFileId, InFile, MacroDefId, MacroFileKind,
 };
 use ra_arena::{map::ArenaMap, Arena};
 use ra_syntax::{ast, AstNode, AstPtr};
@@ -15,9 +15,10 @@ use rustc_hash::FxHashMap;
 use crate::{
     db::DefDatabase,
     expr::{Expr, ExprId, Pat, PatId},
-    nameres::CrateDefMap,
+    nameres::{BuiltinShadowMode, CrateDefMap},
     path::Path,
-    DefWithBodyId, HasModule, HasSource, Lookup, ModuleId,
+    src::HasSource,
+    DefWithBodyId, HasModule, Lookup, ModuleId,
 };
 
 struct Expander {
@@ -73,8 +74,8 @@ impl Expander {
         std::mem::forget(mark);
     }
 
-    fn to_source<T>(&self, value: T) -> Source<T> {
-        Source { file_id: self.current_file_id, value }
+    fn to_source<T>(&self, value: T) -> InFile<T> {
+        InFile { file_id: self.current_file_id, value }
     }
 
     fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
@@ -82,7 +83,10 @@ impl Expander {
     }
 
     fn resolve_path_as_macro(&self, db: &impl DefDatabase, path: &Path) -> Option<MacroDefId> {
-        self.crate_def_map.resolve_path(db, self.module.local_id, path).0.take_macros()
+        self.crate_def_map
+            .resolve_path(db, self.module.local_id, path, BuiltinShadowMode::Other)
+            .0
+            .take_macros()
     }
 }
 
@@ -115,10 +119,10 @@ pub struct Body {
 }
 
 pub type ExprPtr = Either<AstPtr<ast::Expr>, AstPtr<ast::RecordField>>;
-pub type ExprSource = Source<ExprPtr>;
+pub type ExprSource = InFile<ExprPtr>;
 
 pub type PatPtr = Either<AstPtr<ast::Pat>, AstPtr<ast::SelfParam>>;
-pub type PatSource = Source<PatPtr>;
+pub type PatSource = InFile<PatPtr>;
 
 /// An item body together with the mapping from syntax nodes to HIR expression
 /// IDs. This is needed to go from e.g. a position in a file to the HIR
@@ -205,7 +209,7 @@ impl BodySourceMap {
         self.expr_map_back.get(expr).copied()
     }
 
-    pub fn node_expr(&self, node: Source<&ast::Expr>) -> Option<ExprId> {
+    pub fn node_expr(&self, node: InFile<&ast::Expr>) -> Option<ExprId> {
         let src = node.map(|it| Either::A(AstPtr::new(it)));
         self.expr_map.get(&src).cloned()
     }
@@ -214,7 +218,7 @@ impl BodySourceMap {
         self.pat_map_back.get(pat).copied()
     }
 
-    pub fn node_pat(&self, node: Source<&ast::Pat>) -> Option<PatId> {
+    pub fn node_pat(&self, node: InFile<&ast::Pat>) -> Option<PatId> {
         let src = node.map(|it| Either::A(AstPtr::new(it)));
         self.pat_map.get(&src).cloned()
     }
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 331736cb2..be1eaa523 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -429,10 +429,19 @@ where
                 let index = self.collect_expr_opt(e.index());
                 self.alloc_expr(Expr::Index { base, index }, syntax_ptr)
             }
+            ast::Expr::RangeExpr(e) => {
+                let lhs = e.start().map(|lhs| self.collect_expr(lhs));
+                let rhs = e.end().map(|rhs| self.collect_expr(rhs));
+                match e.op_kind() {
+                    Some(range_type) => {
+                        self.alloc_expr(Expr::Range { lhs, rhs, range_type }, syntax_ptr)
+                    }
+                    None => self.alloc_expr(Expr::Missing, syntax_ptr),
+                }
+            }
 
             // FIXME implement HIR for these:
             ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
-            ast::Expr::RangeExpr(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),
             ast::Expr::MacroCall(e) => match self.expander.enter_expand(self.db, e) {
                 Some((mark, expansion)) => {
                     let id = self.collect_expr(expansion);
diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
index 625aa39dd..ab6599b23 100644
--- a/crates/ra_hir_def/src/body/scope.rs
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -171,7 +171,7 @@ fn compute_expr_scopes(expr: ExprId, body: &Body, scopes: &mut ExprScopes, scope
 
 #[cfg(test)]
 mod tests {
-    use hir_expand::{name::AsName, Source};
+    use hir_expand::{name::AsName, InFile};
     use ra_db::{fixture::WithFixture, FileId, SourceDatabase};
     use ra_syntax::{algo::find_node_at_offset, ast, AstNode};
     use test_utils::{assert_eq_text, covers, extract_offset};
@@ -211,7 +211,7 @@ mod tests {
         let (_body, source_map) = db.body_with_source_map(function.into());
 
         let expr_id = source_map
-            .node_expr(Source { file_id: file_id.into(), value: &marker.into() })
+            .node_expr(InFile { file_id: file_id.into(), value: &marker.into() })
             .unwrap();
         let scope = scopes.scope_for(expr_id);
 
@@ -318,7 +318,7 @@ mod tests {
         let expr_scope = {
             let expr_ast = name_ref.syntax().ancestors().find_map(ast::Expr::cast).unwrap();
             let expr_id =
-                source_map.node_expr(Source { file_id: file_id.into(), value: &expr_ast }).unwrap();
+                source_map.node_expr(InFile { file_id: file_id.into(), value: &expr_ast }).unwrap();
             scopes.scope_for(expr_id).unwrap()
         };
 
diff --git a/crates/ra_hir_def/src/data.rs b/crates/ra_hir_def/src/data.rs
index fee10b237..095d7064a 100644
--- a/crates/ra_hir_def/src/data.rs
+++ b/crates/ra_hir_def/src/data.rs
@@ -10,9 +10,10 @@ use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
 
 use crate::{
     db::DefDatabase,
+    src::HasSource,
     type_ref::{Mutability, TypeRef},
-    AssocItemId, AstItemDef, ConstId, ConstLoc, ContainerId, FunctionId, FunctionLoc, HasSource,
-    ImplId, Intern, Lookup, StaticId, TraitId, TypeAliasId, TypeAliasLoc,
+    AssocItemId, AstItemDef, ConstId, ConstLoc, ContainerId, FunctionId, FunctionLoc, ImplId,
+    Intern, Lookup, StaticId, TraitId, TypeAliasId, TypeAliasLoc,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
diff --git a/crates/ra_hir_def/src/diagnostics.rs b/crates/ra_hir_def/src/diagnostics.rs
index eda9b2269..095498429 100644
--- a/crates/ra_hir_def/src/diagnostics.rs
+++ b/crates/ra_hir_def/src/diagnostics.rs
@@ -6,7 +6,7 @@ use hir_expand::diagnostics::Diagnostic;
 use ra_db::RelativePathBuf;
 use ra_syntax::{ast, AstPtr, SyntaxNodePtr};
 
-use hir_expand::{HirFileId, Source};
+use hir_expand::{HirFileId, InFile};
 
 #[derive(Debug)]
 pub struct UnresolvedModule {
@@ -19,8 +19,8 @@ impl Diagnostic for UnresolvedModule {
     fn message(&self) -> String {
         "unresolved module".to_string()
     }
-    fn source(&self) -> Source<SyntaxNodePtr> {
-        Source { file_id: self.file, value: self.decl.into() }
+    fn source(&self) -> InFile<SyntaxNodePtr> {
+        InFile { file_id: self.file, value: self.decl.into() }
     }
     fn as_any(&self) -> &(dyn Any + Send + 'static) {
         self
diff --git a/crates/ra_hir_def/src/docs.rs b/crates/ra_hir_def/src/docs.rs
index 34ed9b7a5..ec944373d 100644
--- a/crates/ra_hir_def/src/docs.rs
+++ b/crates/ra_hir_def/src/docs.rs
@@ -8,7 +8,11 @@ use std::sync::Arc;
 use hir_expand::either::Either;
 use ra_syntax::ast;
 
-use crate::{db::DefDatabase, AdtId, AstItemDef, AttrDefId, HasChildSource, HasSource, Lookup};
+use crate::{
+    db::DefDatabase,
+    src::{HasChildSource, HasSource},
+    AdtId, AstItemDef, AttrDefId, Lookup,
+};
 
 /// Holds documentation
 #[derive(Debug, Clone, PartialEq, Eq)]
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index 04c1d8f69..6fad80a8d 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -14,6 +14,7 @@
 
 use hir_expand::name::Name;
 use ra_arena::{impl_arena_id, RawId};
+use ra_syntax::ast::RangeOp;
 
 use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt},
@@ -130,6 +131,11 @@ pub enum Expr {
         rhs: ExprId,
         op: Option<BinaryOp>,
     },
+    Range {
+        lhs: Option<ExprId>,
+        rhs: Option<ExprId>,
+        range_type: RangeOp,
+    },
     Index {
         base: ExprId,
         index: ExprId,
@@ -288,6 +294,14 @@ impl Expr {
                 f(*lhs);
                 f(*rhs);
             }
+            Expr::Range { lhs, rhs, .. } => {
+                if let Some(lhs) = rhs {
+                    f(*lhs);
+                }
+                if let Some(rhs) = lhs {
+                    f(*rhs);
+                }
+            }
             Expr::Index { base, index } => {
                 f(*base);
                 f(*index);
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index 3f94e40e4..5f648ffc3 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -9,8 +9,9 @@ use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 
 use crate::{
     db::DefDatabase,
+    src::HasSource,
     type_ref::{TypeBound, TypeRef},
-    AdtId, AstItemDef, ContainerId, GenericDefId, HasSource, Lookup,
+    AdtId, AstItemDef, ContainerId, GenericDefId, Lookup,
 };
 
 /// Data about a generic parameter (to a function, struct, impl, ...).
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index bc5530896..cfeacfded 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -29,6 +29,8 @@ pub mod resolver;
 mod trace;
 pub mod nameres;
 
+pub mod src;
+
 #[cfg(test)]
 mod test_db;
 #[cfg(test)]
@@ -36,8 +38,8 @@ mod marks;
 
 use std::hash::{Hash, Hasher};
 
-use hir_expand::{ast_id_map::FileAstId, db::AstDatabase, AstId, HirFileId, MacroDefId, Source};
-use ra_arena::{impl_arena_id, map::ArenaMap, RawId};
+use hir_expand::{ast_id_map::FileAstId, db::AstDatabase, AstId, HirFileId, InFile, MacroDefId};
+use ra_arena::{impl_arena_id, RawId};
 use ra_db::{impl_intern_key, salsa, CrateId};
 use ra_syntax::{ast, AstNode};
 
@@ -105,10 +107,10 @@ pub trait AstItemDef<N: AstNode>: salsa::InternKey + Clone {
         let loc = ItemLoc { module: ctx.module, ast_id: AstId::new(ctx.file_id, ast_id) };
         Self::intern(ctx.db, loc)
     }
-    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> Source<N> {
+    fn source(self, db: &(impl AstDatabase + InternDatabase)) -> InFile<N> {
         let loc = self.lookup_intern(db);
         let value = loc.ast_id.to_node(db);
-        Source { file_id: loc.ast_id.file_id(), value }
+        InFile { file_id: loc.ast_id.file_id, value }
     }
     fn module(self, db: &impl InternDatabase) -> ModuleId {
         let loc = self.lookup_intern(db);
@@ -514,53 +516,3 @@ impl HasModule for StaticLoc {
         self.container
     }
 }
-
-pub trait HasSource {
-    type Value;
-    fn source(&self, db: &impl db::DefDatabase) -> Source<Self::Value>;
-}
-
-impl HasSource for FunctionLoc {
-    type Value = ast::FnDef;
-
-    fn source(&self, db: &impl db::DefDatabase) -> Source<ast::FnDef> {
-        let node = self.ast_id.to_node(db);
-        Source::new(self.ast_id.file_id(), node)
-    }
-}
-
-impl HasSource for TypeAliasLoc {
-    type Value = ast::TypeAliasDef;
-
-    fn source(&self, db: &impl db::DefDatabase) -> Source<ast::TypeAliasDef> {
-        let node = self.ast_id.to_node(db);
-        Source::new(self.ast_id.file_id(), node)
-    }
-}
-
-impl HasSource for ConstLoc {
-    type Value = ast::ConstDef;
-
-    fn source(&self, db: &impl db::DefDatabase) -> Source<ast::ConstDef> {
-        let node = self.ast_id.to_node(db);
-        Source::new(self.ast_id.file_id(), node)
-    }
-}
-
-impl HasSource for StaticLoc {
-    type Value = ast::StaticDef;
-
-    fn source(&self, db: &impl db::DefDatabase) -> Source<ast::StaticDef> {
-        let node = self.ast_id.to_node(db);
-        Source::new(self.ast_id.file_id(), node)
-    }
-}
-
-pub trait HasChildSource {
-    type ChildId;
-    type Value;
-    fn child_source(
-        &self,
-        db: &impl db::DefDatabase,
-    ) -> Source<ArenaMap<Self::ChildId, Self::Value>>;
-}
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 2359386c2..3e1521870 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -58,8 +58,8 @@ mod tests;
 use std::sync::Arc;
 
 use hir_expand::{
-    ast_id_map::FileAstId, diagnostics::DiagnosticSink, either::Either, name::Name, MacroDefId,
-    Source,
+    ast_id_map::FileAstId, diagnostics::DiagnosticSink, either::Either, name::Name, InFile,
+    MacroDefId,
 };
 use once_cell::sync::Lazy;
 use ra_arena::Arena;
@@ -149,6 +149,15 @@ static BUILTIN_SCOPE: Lazy<FxHashMap<Name, Resolution>> = Lazy::new(|| {
         .collect()
 });
 
+/// Shadow mode for builtin type which can be shadowed by module.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum BuiltinShadowMode {
+    // Prefer Module
+    Module,
+    // Prefer Other Types
+    Other,
+}
+
 /// Legacy macros can only be accessed through special methods like `get_legacy_macros`.
 /// Other methods will only resolve values, types and module scoped macros only.
 impl ModuleScope {
@@ -178,8 +187,20 @@ impl ModuleScope {
     }
 
     /// Get a name from current module scope, legacy macros are not included
-    pub fn get(&self, name: &Name) -> Option<&Resolution> {
-        self.items.get(name).or_else(|| BUILTIN_SCOPE.get(name))
+    pub fn get(&self, name: &Name, shadow: BuiltinShadowMode) -> Option<&Resolution> {
+        match shadow {
+            BuiltinShadowMode::Module => self.items.get(name).or_else(|| BUILTIN_SCOPE.get(name)),
+            BuiltinShadowMode::Other => {
+                let item = self.items.get(name);
+                if let Some(res) = item {
+                    if let Some(ModuleDefId::ModuleId(_)) = res.def.take_types() {
+                        return BUILTIN_SCOPE.get(name).or(item);
+                    }
+                }
+
+                item.or_else(|| BUILTIN_SCOPE.get(name))
+            }
+        }
     }
 
     pub fn traits<'a>(&'a self) -> impl Iterator<Item = TraitId> + 'a {
@@ -250,8 +271,10 @@ impl CrateDefMap {
         db: &impl DefDatabase,
         original_module: LocalModuleId,
         path: &Path,
+        shadow: BuiltinShadowMode,
     ) -> (PerNs, Option<usize>) {
-        let res = self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path);
+        let res =
+            self.resolve_path_fp_with_macro(db, ResolveMode::Other, original_module, path, shadow);
         (res.resolved_def, res.segment_index)
     }
 }
@@ -261,21 +284,21 @@ impl ModuleData {
     pub fn definition_source(
         &self,
         db: &impl DefDatabase,
-    ) -> Source<Either<ast::SourceFile, ast::Module>> {
+    ) -> InFile<Either<ast::SourceFile, ast::Module>> {
         if let Some(file_id) = self.definition {
             let sf = db.parse(file_id).tree();
-            return Source::new(file_id.into(), Either::A(sf));
+            return InFile::new(file_id.into(), Either::A(sf));
         }
         let decl = self.declaration.unwrap();
-        Source::new(decl.file_id(), Either::B(decl.to_node(db)))
+        InFile::new(decl.file_id, Either::B(decl.to_node(db)))
     }
 
     /// Returns a node which declares this module, either a `mod foo;` or a `mod foo {}`.
     /// `None` for the crate root.
-    pub fn declaration_source(&self, db: &impl DefDatabase) -> Option<Source<ast::Module>> {
+    pub fn declaration_source(&self, db: &impl DefDatabase) -> Option<InFile<ast::Module>> {
         let decl = self.declaration?;
         let value = decl.to_node(db);
-        Some(Source { file_id: decl.file_id(), value })
+        Some(InFile { file_id: decl.file_id, value })
     }
 }
 
@@ -309,7 +332,7 @@ mod diagnostics {
                     }
                     let decl = declaration.to_node(db);
                     sink.push(UnresolvedModule {
-                        file: declaration.file_id(),
+                        file: declaration.file_id,
                         decl: AstPtr::new(&decl),
                         candidate: candidate.clone(),
                     })
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index fd8245113..d4bfcae1d 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -19,7 +19,7 @@ use crate::{
     db::DefDatabase,
     nameres::{
         diagnostics::DefDiagnostic, mod_resolution::ModDir, path_resolution::ReachedFixedPoint,
-        raw, CrateDefMap, ModuleData, Resolution, ResolveMode,
+        raw, BuiltinShadowMode, CrateDefMap, ModuleData, Resolution, ResolveMode,
     },
     path::{Path, PathKind},
     per_ns::PerNs,
@@ -299,6 +299,7 @@ where
                 ResolveMode::Import,
                 module_id,
                 &import.path,
+                BuiltinShadowMode::Module,
             );
 
             (res.resolved_def, res.reached_fixedpoint)
@@ -477,6 +478,7 @@ where
                 ResolveMode::Other,
                 *module_id,
                 path,
+                BuiltinShadowMode::Module,
             );
 
             if let Some(def) = resolved_res.resolved_def.take_macros() {
diff --git a/crates/ra_hir_def/src/nameres/path_resolution.rs b/crates/ra_hir_def/src/nameres/path_resolution.rs
index b72c55bd1..42a75226b 100644
--- a/crates/ra_hir_def/src/nameres/path_resolution.rs
+++ b/crates/ra_hir_def/src/nameres/path_resolution.rs
@@ -16,7 +16,7 @@ use test_utils::tested_by;
 
 use crate::{
     db::DefDatabase,
-    nameres::CrateDefMap,
+    nameres::{BuiltinShadowMode, CrateDefMap},
     path::{Path, PathKind},
     per_ns::PerNs,
     AdtId, EnumVariantId, LocalModuleId, ModuleDefId, ModuleId,
@@ -68,7 +68,17 @@ impl CrateDefMap {
         mode: ResolveMode,
         original_module: LocalModuleId,
         path: &Path,
+        shadow: BuiltinShadowMode,
     ) -> ResolvePathResult {
+        // if it is not the last segment, we prefer the module to the builtin
+        let prefer_module = |index| {
+            if index == path.segments.len() - 1 {
+                shadow
+            } else {
+                BuiltinShadowMode::Module
+            }
+        };
+
         let mut segments = path.segments.iter().enumerate();
         let mut curr_per_ns: PerNs = match path.kind {
             PathKind::DollarCrate(krate) => {
@@ -96,20 +106,20 @@ impl CrateDefMap {
                 if self.edition == Edition::Edition2015
                     && (path.kind == PathKind::Abs || mode == ResolveMode::Import) =>
             {
-                let segment = match segments.next() {
-                    Some((_, segment)) => segment,
+                let (idx, segment) = match segments.next() {
+                    Some((idx, segment)) => (idx, segment),
                     None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
                 };
                 log::debug!("resolving {:?} in crate root (+ extern prelude)", segment);
-                self.resolve_name_in_crate_root_or_extern_prelude(&segment.name)
+                self.resolve_name_in_crate_root_or_extern_prelude(&segment.name, prefer_module(idx))
             }
             PathKind::Plain => {
-                let segment = match segments.next() {
-                    Some((_, segment)) => segment,
+                let (idx, segment) = match segments.next() {
+                    Some((idx, segment)) => (idx, segment),
                     None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
                 };
                 log::debug!("resolving {:?} in module", segment);
-                self.resolve_name_in_module(db, original_module, &segment.name)
+                self.resolve_name_in_module(db, original_module, &segment.name, prefer_module(idx))
             }
             PathKind::Super => {
                 if let Some(p) = self.modules[original_module].parent {
@@ -160,7 +170,7 @@ impl CrateDefMap {
                             Path { segments: path.segments[i..].to_vec(), kind: PathKind::Self_ };
                         log::debug!("resolving {:?} in other crate", path);
                         let defp_map = db.crate_def_map(module.krate);
-                        let (def, s) = defp_map.resolve_path(db, module.local_id, &path);
+                        let (def, s) = defp_map.resolve_path(db, module.local_id, &path, shadow);
                         return ResolvePathResult::with(
                             def,
                             ReachedFixedPoint::Yes,
@@ -169,7 +179,7 @@ impl CrateDefMap {
                     }
 
                     // Since it is a qualified path here, it should not contains legacy macros
-                    match self[module.local_id].scope.get(&segment.name) {
+                    match self[module.local_id].scope.get(&segment.name, prefer_module(i)) {
                         Some(res) => res.def,
                         _ => {
                             log::debug!("path segment {:?} not found", segment.name);
@@ -212,6 +222,7 @@ impl CrateDefMap {
                 }
             };
         }
+
         ResolvePathResult::with(curr_per_ns, ReachedFixedPoint::Yes, None)
     }
 
@@ -220,6 +231,7 @@ impl CrateDefMap {
         db: &impl DefDatabase,
         module: LocalModuleId,
         name: &Name,
+        shadow: BuiltinShadowMode,
     ) -> PerNs {
         // Resolve in:
         //  - legacy scope of macro
@@ -228,23 +240,33 @@ impl CrateDefMap {
         //  - std prelude
         let from_legacy_macro =
             self[module].scope.get_legacy_macro(name).map_or_else(PerNs::none, PerNs::macros);
-        let from_scope = self[module].scope.get(name).map_or_else(PerNs::none, |res| res.def);
+        let from_scope =
+            self[module].scope.get(name, shadow).map_or_else(PerNs::none, |res| res.def);
         let from_extern_prelude =
             self.extern_prelude.get(name).map_or(PerNs::none(), |&it| PerNs::types(it));
-        let from_prelude = self.resolve_in_prelude(db, name);
+        let from_prelude = self.resolve_in_prelude(db, name, shadow);
 
         from_legacy_macro.or(from_scope).or(from_extern_prelude).or(from_prelude)
     }
 
-    fn resolve_name_in_crate_root_or_extern_prelude(&self, name: &Name) -> PerNs {
+    fn resolve_name_in_crate_root_or_extern_prelude(
+        &self,
+        name: &Name,
+        shadow: BuiltinShadowMode,
+    ) -> PerNs {
         let from_crate_root =
-            self[self.root].scope.get(name).map_or_else(PerNs::none, |res| res.def);
+            self[self.root].scope.get(name, shadow).map_or_else(PerNs::none, |res| res.def);
         let from_extern_prelude = self.resolve_name_in_extern_prelude(name);
 
         from_crate_root.or(from_extern_prelude)
     }
 
-    fn resolve_in_prelude(&self, db: &impl DefDatabase, name: &Name) -> PerNs {
+    fn resolve_in_prelude(
+        &self,
+        db: &impl DefDatabase,
+        name: &Name,
+        shadow: BuiltinShadowMode,
+    ) -> PerNs {
         if let Some(prelude) = self.prelude {
             let keep;
             let def_map = if prelude.krate == self.krate {
@@ -254,7 +276,10 @@ impl CrateDefMap {
                 keep = db.crate_def_map(prelude.krate);
                 &keep
             };
-            def_map[prelude.local_id].scope.get(name).map_or_else(PerNs::none, |res| res.def)
+            def_map[prelude.local_id]
+                .scope
+                .get(name, shadow)
+                .map_or_else(PerNs::none, |res| res.def)
         } else {
             PerNs::none()
         }
diff --git a/crates/ra_hir_def/src/nameres/raw.rs b/crates/ra_hir_def/src/nameres/raw.rs
index 6eb106094..5196b67ca 100644
--- a/crates/ra_hir_def/src/nameres/raw.rs
+++ b/crates/ra_hir_def/src/nameres/raw.rs
@@ -22,8 +22,8 @@ use ra_syntax::{
 use test_utils::tested_by;
 
 use crate::{
-    attr::Attrs, db::DefDatabase, path::Path, trace::Trace, FileAstId, HirFileId, LocalImportId,
-    Source,
+    attr::Attrs, db::DefDatabase, path::Path, trace::Trace, FileAstId, HirFileId, InFile,
+    LocalImportId,
 };
 
 /// `RawItems` is a set of top-level items in a file (except for impls).
@@ -313,7 +313,7 @@ impl RawItemsCollector {
 
         let mut buf = Vec::new();
         Path::expand_use_item(
-            Source { value: use_item, file_id: self.file_id },
+            InFile { value: use_item, file_id: self.file_id },
             &self.hygiene,
             |path, use_tree, is_glob, alias| {
                 let import_data = ImportData {
diff --git a/crates/ra_hir_def/src/nameres/tests/mod_resolution.rs b/crates/ra_hir_def/src/nameres/tests/mod_resolution.rs
index e11530062..e800cc68e 100644
--- a/crates/ra_hir_def/src/nameres/tests/mod_resolution.rs
+++ b/crates/ra_hir_def/src/nameres/tests/mod_resolution.rs
@@ -668,7 +668,7 @@ fn unresolved_module_diagnostics() {
             module: LocalModuleId(
                 0,
             ),
-            declaration: AstId {
+            declaration: InFile {
                 file_id: HirFileId(
                     FileId(
                         FileId(
@@ -676,7 +676,7 @@ fn unresolved_module_diagnostics() {
                         ),
                     ),
                 ),
-                file_ast_id: FileAstId {
+                value: FileAstId {
                     raw: ErasedFileAstId(
                         1,
                     ),
diff --git a/crates/ra_hir_def/src/path.rs b/crates/ra_hir_def/src/path.rs
index 6810a26db..ff252fe44 100644
--- a/crates/ra_hir_def/src/path.rs
+++ b/crates/ra_hir_def/src/path.rs
@@ -13,7 +13,7 @@ use ra_syntax::{
     AstNode,
 };
 
-use crate::{type_ref::TypeRef, Source};
+use crate::{type_ref::TypeRef, InFile};
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Path {
@@ -67,7 +67,7 @@ pub enum PathKind {
 impl Path {
     /// Calls `cb` with all paths, represented by this use item.
     pub(crate) fn expand_use_item(
-        item_src: Source<ast::UseItem>,
+        item_src: InFile<ast::UseItem>,
         hygiene: &Hygiene,
         mut cb: impl FnMut(Path, &ast::UseTree, bool, Option<Name>),
     ) {
@@ -409,6 +409,36 @@ pub mod known {
         Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::TRY_TYPE])
     }
 
+    pub fn std_ops_range() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_TYPE])
+    }
+
+    pub fn std_ops_range_from() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_FROM_TYPE])
+    }
+
+    pub fn std_ops_range_full() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_FULL_TYPE])
+    }
+
+    pub fn std_ops_range_inclusive() -> Path {
+        Path::from_simple_segments(
+            PathKind::Abs,
+            vec![name::STD, name::OPS, name::RANGE_INCLUSIVE_TYPE],
+        )
+    }
+
+    pub fn std_ops_range_to() -> Path {
+        Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::OPS, name::RANGE_TO_TYPE])
+    }
+
+    pub fn std_ops_range_to_inclusive() -> Path {
+        Path::from_simple_segments(
+            PathKind::Abs,
+            vec![name::STD, name::OPS, name::RANGE_TO_INCLUSIVE_TYPE],
+        )
+    }
+
     pub fn std_result_result() -> Path {
         Path::from_simple_segments(PathKind::Abs, vec![name::STD, name::RESULT, name::RESULT_TYPE])
     }
diff --git a/crates/ra_hir_def/src/resolver.rs b/crates/ra_hir_def/src/resolver.rs
index 0847f6dcf..7d4df222e 100644
--- a/crates/ra_hir_def/src/resolver.rs
+++ b/crates/ra_hir_def/src/resolver.rs
@@ -14,7 +14,7 @@ use crate::{
     db::DefDatabase,
     expr::{ExprId, PatId},
     generics::GenericParams,
-    nameres::CrateDefMap,
+    nameres::{BuiltinShadowMode, CrateDefMap},
     path::{Path, PathKind},
     per_ns::PerNs,
     AdtId, AstItemDef, ConstId, ContainerId, DefWithBodyId, EnumId, EnumVariantId, FunctionId,
@@ -91,7 +91,7 @@ pub enum ValueNs {
 impl Resolver {
     /// Resolve known trait from std, like `std::futures::Future`
     pub fn resolve_known_trait(&self, db: &impl DefDatabase, path: &Path) -> Option<TraitId> {
-        let res = self.resolve_module_path(db, path).take_types()?;
+        let res = self.resolve_module_path(db, path, BuiltinShadowMode::Other).take_types()?;
         match res {
             ModuleDefId::TraitId(it) => Some(it),
             _ => None,
@@ -100,7 +100,7 @@ impl Resolver {
 
     /// Resolve known struct from std, like `std::boxed::Box`
     pub fn resolve_known_struct(&self, db: &impl DefDatabase, path: &Path) -> Option<StructId> {
-        let res = self.resolve_module_path(db, path).take_types()?;
+        let res = self.resolve_module_path(db, path, BuiltinShadowMode::Other).take_types()?;
         match res {
             ModuleDefId::AdtId(AdtId::StructId(it)) => Some(it),
             _ => None,
@@ -109,26 +109,34 @@ impl Resolver {
 
     /// Resolve known enum from std, like `std::result::Result`
     pub fn resolve_known_enum(&self, db: &impl DefDatabase, path: &Path) -> Option<EnumId> {
-        let res = self.resolve_module_path(db, path).take_types()?;
+        let res = self.resolve_module_path(db, path, BuiltinShadowMode::Other).take_types()?;
         match res {
             ModuleDefId::AdtId(AdtId::EnumId(it)) => Some(it),
             _ => None,
         }
     }
 
-    /// pub only for source-binder
-    pub fn resolve_module_path(&self, db: &impl DefDatabase, path: &Path) -> PerNs {
+    fn resolve_module_path(
+        &self,
+        db: &impl DefDatabase,
+        path: &Path,
+        shadow: BuiltinShadowMode,
+    ) -> PerNs {
         let (item_map, module) = match self.module() {
             Some(it) => it,
             None => return PerNs::none(),
         };
-        let (module_res, segment_index) = item_map.resolve_path(db, module, path);
+        let (module_res, segment_index) = item_map.resolve_path(db, module, path, shadow);
         if segment_index.is_some() {
             return PerNs::none();
         }
         module_res
     }
 
+    pub fn resolve_module_path_in_items(&self, db: &impl DefDatabase, path: &Path) -> PerNs {
+        self.resolve_module_path(db, path, BuiltinShadowMode::Module)
+    }
+
     pub fn resolve_path_in_type_ns(
         &self,
         db: &impl DefDatabase,
@@ -163,7 +171,12 @@ impl Resolver {
                     }
                 }
                 Scope::ModuleScope(m) => {
-                    let (module_def, idx) = m.crate_def_map.resolve_path(db, m.module_id, path);
+                    let (module_def, idx) = m.crate_def_map.resolve_path(
+                        db,
+                        m.module_id,
+                        path,
+                        BuiltinShadowMode::Other,
+                    );
                     let res = match module_def.take_types()? {
                         ModuleDefId::AdtId(it) => TypeNs::AdtId(it),
                         ModuleDefId::EnumVariantId(it) => TypeNs::EnumVariantId(it),
@@ -256,7 +269,12 @@ impl Resolver {
                 Scope::ImplBlockScope(_) | Scope::AdtScope(_) => continue,
 
                 Scope::ModuleScope(m) => {
-                    let (module_def, idx) = m.crate_def_map.resolve_path(db, m.module_id, path);
+                    let (module_def, idx) = m.crate_def_map.resolve_path(
+                        db,
+                        m.module_id,
+                        path,
+                        BuiltinShadowMode::Other,
+                    );
                     return match idx {
                         None => {
                             let value = match module_def.take_values()? {
@@ -310,7 +328,7 @@ impl Resolver {
 
     pub fn resolve_path_as_macro(&self, db: &impl DefDatabase, path: &Path) -> Option<MacroDefId> {
         let (item_map, module) = self.module()?;
-        item_map.resolve_path(db, module, path).0.take_macros()
+        item_map.resolve_path(db, module, path, BuiltinShadowMode::Other).0.take_macros()
     }
 
     pub fn process_all_names(&self, db: &impl DefDatabase, f: &mut dyn FnMut(Name, ScopeDef)) {
diff --git a/crates/ra_hir_def/src/src.rs b/crates/ra_hir_def/src/src.rs
new file mode 100644
index 000000000..27caa02cc
--- /dev/null
+++ b/crates/ra_hir_def/src/src.rs
@@ -0,0 +1,54 @@
+//! Utilities for mapping between hir IDs and the surface syntax.
+
+use hir_expand::InFile;
+use ra_arena::map::ArenaMap;
+use ra_syntax::ast;
+
+use crate::{db::DefDatabase, ConstLoc, FunctionLoc, StaticLoc, TypeAliasLoc};
+
+pub trait HasSource {
+    type Value;
+    fn source(&self, db: &impl DefDatabase) -> InFile<Self::Value>;
+}
+
+impl HasSource for FunctionLoc {
+    type Value = ast::FnDef;
+
+    fn source(&self, db: &impl DefDatabase) -> InFile<ast::FnDef> {
+        let node = self.ast_id.to_node(db);
+        InFile::new(self.ast_id.file_id, node)
+    }
+}
+
+impl HasSource for TypeAliasLoc {
+    type Value = ast::TypeAliasDef;
+
+    fn source(&self, db: &impl DefDatabase) -> InFile<ast::TypeAliasDef> {
+        let node = self.ast_id.to_node(db);
+        InFile::new(self.ast_id.file_id, node)
+    }
+}
+
+impl HasSource for ConstLoc {
+    type Value = ast::ConstDef;
+
+    fn source(&self, db: &impl DefDatabase) -> InFile<ast::ConstDef> {
+        let node = self.ast_id.to_node(db);
+        InFile::new(self.ast_id.file_id, node)
+    }
+}
+
+impl HasSource for StaticLoc {
+    type Value = ast::StaticDef;
+
+    fn source(&self, db: &impl DefDatabase) -> InFile<ast::StaticDef> {
+        let node = self.ast_id.to_node(db);
+        InFile::new(self.ast_id.file_id, node)
+    }
+}
+
+pub trait HasChildSource {
+    type ChildId;
+    type Value;
+    fn child_source(&self, db: &impl DefDatabase) -> InFile<ArenaMap<Self::ChildId, Self::Value>>;
+}