14 files changed, 172 insertions, 80 deletions

diff --git a/crates/ra_assists/src/assist_ctx.rs b/crates/ra_assists/src/assist_ctx.rs
index 2fe7c3de3..3155a469b 100644
--- a/crates/ra_assists/src/assist_ctx.rs
+++ b/crates/ra_assists/src/assist_ctx.rs
@@ -1,12 +1,12 @@
 //! This module defines `AssistCtx` -- the API surface that is exposed to assists.
 use hir::Semantics;
-use ra_db::FileRange;
+use ra_db::{FileRange, Upcast};
 use ra_fmt::{leading_indent, reindent};
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
     algo::{self, find_covering_element, find_node_at_offset},
-    AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange, TextSize,
-    TokenAtOffset,
+    ast, AstNode, SourceFile, SyntaxElement, SyntaxKind, SyntaxNode, SyntaxToken, TextRange,
+    TextSize, TokenAtOffset,
 };
 use ra_text_edit::TextEditBuilder;
 
@@ -136,6 +136,9 @@ impl<'a> AssistCtx<'a> {
     pub(crate) fn covering_node_for_range(&self, range: TextRange) -> SyntaxElement {
         find_covering_element(self.source_file.syntax(), range)
     }
+    pub(crate) fn lower_path(&self, path: ast::Path) -> Option<hir::Path> {
+        hir::Path::from_src(path, &hir::Hygiene::new(self.db.upcast(), self.frange.file_id.into()))
+    }
 }
 
 pub(crate) struct AssistGroup<'a> {
diff --git a/crates/ra_assists/src/ast_transform.rs b/crates/ra_assists/src/ast_transform.rs
index 52b4c82db..9ac65ab39 100644
--- a/crates/ra_assists/src/ast_transform.rs
+++ b/crates/ra_assists/src/ast_transform.rs
@@ -85,6 +85,7 @@ impl<'a> SubstituteTypeParams<'a> {
             ast::TypeRef::PathType(path_type) => path_type.path()?,
             _ => return None,
         };
+        // FIXME: use `hir::Path::from_src` instead.
         let path = hir::Path::from_ast(path)?;
         let resolution = self.source_scope.resolve_hir_path(&path)?;
         match resolution {
@@ -128,6 +129,7 @@ impl<'a> QualifyPaths<'a> {
             // don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway
             return None;
         }
+        // FIXME: use `hir::Path::from_src` instead.
         let hir_path = hir::Path::from_ast(p.clone());
         let resolution = self.source_scope.resolve_hir_path(&hir_path?)?;
         match resolution {
diff --git a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
index 2f02df303..ad59db392 100644
--- a/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
+++ b/crates/ra_assists/src/handlers/replace_qualified_name_with_use.rs
@@ -27,7 +27,7 @@ pub(crate) fn replace_qualified_name_with_use(ctx: AssistCtx) -> Option<Assist>
         return None;
     }
 
-    let hir_path = hir::Path::from_ast(path.clone())?;
+    let hir_path = ctx.lower_path(path.clone())?;
     let segments = collect_hir_path_segments(&hir_path)?;
     if segments.len() < 2 {
         return None;
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 312ef3814..c5df4ac24 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -70,6 +70,7 @@ pub use hir_def::{
     type_ref::Mutability,
 };
 pub use hir_expand::{
-    name::Name, HirFileId, InFile, MacroCallId, MacroCallLoc, MacroDefId, MacroFile, Origin,
+    hygiene::Hygiene, name::Name, HirFileId, InFile, MacroCallId, MacroCallLoc, MacroDefId,
+    MacroFile, Origin,
 };
 pub use hir_ty::{display::HirDisplay, CallableDef};
diff --git a/crates/ra_hir/src/source_analyzer.rs b/crates/ra_hir/src/source_analyzer.rs
index 74d64c97d..c63d1b847 100644
--- a/crates/ra_hir/src/source_analyzer.rs
+++ b/crates/ra_hir/src/source_analyzer.rs
@@ -224,7 +224,8 @@ impl SourceAnalyzer {
             }
         }
         // This must be a normal source file rather than macro file.
-        let hir_path = crate::Path::from_ast(path.clone())?;
+        let hir_path =
+            crate::Path::from_src(path.clone(), &Hygiene::new(db.upcast(), self.file_id))?;
         resolve_hir_path(db, &self.resolver, &hir_path)
     }
 
diff --git a/crates/ra_hir_def/src/adt.rs b/crates/ra_hir_def/src/adt.rs
index 753becc3d..8eef51828 100644
--- a/crates/ra_hir_def/src/adt.rs
+++ b/crates/ra_hir_def/src/adt.rs
@@ -12,9 +12,15 @@ use ra_prof::profile;
 use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner, VisibilityOwner};
 
 use crate::{
-    body::CfgExpander, db::DefDatabase, src::HasChildSource, src::HasSource, trace::Trace,
-    type_ref::TypeRef, visibility::RawVisibility, EnumId, HasModule, LocalEnumVariantId,
-    LocalFieldId, Lookup, ModuleId, StructId, UnionId, VariantId,
+    body::{CfgExpander, LowerCtx},
+    db::DefDatabase,
+    src::HasChildSource,
+    src::HasSource,
+    trace::Trace,
+    type_ref::TypeRef,
+    visibility::RawVisibility,
+    EnumId, HasModule, LocalEnumVariantId, LocalFieldId, Lookup, ModuleId, StructId, UnionId,
+    VariantId,
 };
 
 /// Note that we use `StructData` for unions as well!
@@ -198,6 +204,8 @@ fn lower_struct(
     trace: &mut Trace<FieldData, Either<ast::TupleFieldDef, ast::RecordFieldDef>>,
     ast: &InFile<ast::StructKind>,
 ) -> StructKind {
+    let ctx = LowerCtx::new(db, ast.file_id);
+
     match &ast.value {
         ast::StructKind::Tuple(fl) => {
             for (i, fd) in fl.fields().enumerate() {
@@ -210,7 +218,7 @@ fn lower_struct(
                     || Either::Left(fd.clone()),
                     || FieldData {
                         name: Name::new_tuple_field(i),
-                        type_ref: TypeRef::from_ast_opt(fd.type_ref()),
+                        type_ref: TypeRef::from_ast_opt(&ctx, fd.type_ref()),
                         visibility: RawVisibility::from_ast(db, ast.with_value(fd.visibility())),
                     },
                 );
@@ -228,7 +236,7 @@ fn lower_struct(
                     || Either::Right(fd.clone()),
                     || FieldData {
                         name: fd.name().map(|n| n.as_name()).unwrap_or_else(Name::missing),
-                        type_ref: TypeRef::from_ast_opt(fd.ascribed_type()),
+                        type_ref: TypeRef::from_ast_opt(&ctx, fd.ascribed_type()),
                         visibility: RawVisibility::from_ast(db, ast.with_value(fd.visibility())),
                     },
                 );
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index 890cefcaf..4edaad960 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -15,6 +15,8 @@ use ra_prof::profile;
 use ra_syntax::{ast, AstNode, AstPtr};
 use rustc_hash::FxHashMap;
 
+pub(crate) use lower::LowerCtx;
+
 use crate::{
     attr::Attrs,
     db::DefDatabase,
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index f467ed3fe..e9dd65b0a 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -3,8 +3,9 @@
 
 use either::Either;
 use hir_expand::{
+    hygiene::Hygiene,
     name::{name, AsName, Name},
-    MacroDefId, MacroDefKind,
+    HirFileId, MacroDefId, MacroDefKind,
 };
 use ra_arena::Arena;
 use ra_syntax::{
@@ -26,7 +27,7 @@ use crate::{
         LogicOp, MatchArm, Ordering, Pat, PatId, RecordFieldPat, RecordLitField, Statement,
     },
     item_scope::BuiltinShadowMode,
-    path::GenericArgs,
+    path::{GenericArgs, Path},
     type_ref::{Mutability, TypeRef},
     AdtId, ConstLoc, ContainerId, DefWithBodyId, EnumLoc, FunctionLoc, Intern, ModuleDefId,
     StaticLoc, StructLoc, TraitLoc, TypeAliasLoc, UnionLoc,
@@ -35,6 +36,23 @@ use crate::{
 use super::{ExprSource, PatSource};
 use ast::AstChildren;
 
+pub(crate) struct LowerCtx {
+    hygiene: Hygiene,
+}
+
+impl LowerCtx {
+    pub fn new(db: &dyn DefDatabase, file_id: HirFileId) -> Self {
+        LowerCtx { hygiene: Hygiene::new(db.upcast(), file_id) }
+    }
+    pub fn with_hygiene(hygiene: &Hygiene) -> Self {
+        LowerCtx { hygiene: hygiene.clone() }
+    }
+
+    pub fn lower_path(&self, ast: ast::Path) -> Option<Path> {
+        Path::from_src(ast, &self.hygiene)
+    }
+}
+
 pub(super) fn lower(
     db: &dyn DefDatabase,
     def: DefWithBodyId,
@@ -42,10 +60,13 @@ pub(super) fn lower(
     params: Option<ast::ParamList>,
     body: Option<ast::Expr>,
 ) -> (Body, BodySourceMap) {
+    let ctx = LowerCtx::new(db, expander.current_file_id.clone());
+
     ExprCollector {
         db,
         def,
         expander,
+        ctx,
         source_map: BodySourceMap::default(),
         body: Body {
             exprs: Arena::default(),
@@ -62,7 +83,7 @@ struct ExprCollector<'a> {
     db: &'a dyn DefDatabase,
     def: DefWithBodyId,
     expander: Expander,
-
+    ctx: LowerCtx,
     body: Body,
     source_map: BodySourceMap,
 }
@@ -237,7 +258,8 @@ impl ExprCollector<'_> {
                     Vec::new()
                 };
                 let method_name = e.name_ref().map(|nr| nr.as_name()).unwrap_or_else(Name::missing);
-                let generic_args = e.type_arg_list().and_then(GenericArgs::from_ast);
+                let generic_args =
+                    e.type_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx, it));
                 self.alloc_expr(
                     Expr::MethodCall { receiver, method_name, args, generic_args },
                     syntax_ptr,
@@ -343,7 +365,7 @@ impl ExprCollector<'_> {
             }
             ast::Expr::CastExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let type_ref = TypeRef::from_ast_opt(e.type_ref());
+                let type_ref = TypeRef::from_ast_opt(&self.ctx, e.type_ref());
                 self.alloc_expr(Expr::Cast { expr, type_ref }, syntax_ptr)
             }
             ast::Expr::RefExpr(e) => {
@@ -365,12 +387,16 @@ impl ExprCollector<'_> {
                 if let Some(pl) = e.param_list() {
                     for param in pl.params() {
                         let pat = self.collect_pat_opt(param.pat());
-                        let type_ref = param.ascribed_type().map(TypeRef::from_ast);
+                        let type_ref =
+                            param.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
                         args.push(pat);
                         arg_types.push(type_ref);
                     }
                 }
-                let ret_type = e.ret_type().and_then(|r| r.type_ref()).map(TypeRef::from_ast);
+                let ret_type = e
+                    .ret_type()
+                    .and_then(|r| r.type_ref())
+                    .map(|it| TypeRef::from_ast(&self.ctx, it));
                 let body = self.collect_expr_opt(e.body());
                 self.alloc_expr(Expr::Lambda { args, arg_types, ret_type, body }, syntax_ptr)
             }
@@ -476,7 +502,7 @@ impl ExprCollector<'_> {
             .map(|s| match s {
                 ast::Stmt::LetStmt(stmt) => {
                     let pat = self.collect_pat_opt(stmt.pat());
-                    let type_ref = stmt.ascribed_type().map(TypeRef::from_ast);
+                    let type_ref = stmt.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
                     let initializer = stmt.initializer().map(|e| self.collect_expr(e));
                     Statement::Let { pat, type_ref, initializer }
                 }
diff --git a/crates/ra_hir_def/src/data.rs b/crates/ra_hir_def/src/data.rs
index ccb682f9a..7a2067e49 100644
--- a/crates/ra_hir_def/src/data.rs
+++ b/crates/ra_hir_def/src/data.rs
@@ -15,6 +15,7 @@ use ra_syntax::ast::{
 
 use crate::{
     attr::Attrs,
+    body::LowerCtx,
     db::DefDatabase,
     path::{path, AssociatedTypeBinding, GenericArgs, Path},
     src::HasSource,
@@ -40,13 +41,14 @@ impl FunctionData {
     pub(crate) fn fn_data_query(db: &impl DefDatabase, func: FunctionId) -> Arc<FunctionData> {
         let loc = func.lookup(db);
         let src = loc.source(db);
+        let ctx = LowerCtx::new(db, src.file_id);
         let name = src.value.name().map(|n| n.as_name()).unwrap_or_else(Name::missing);
         let mut params = Vec::new();
         let mut has_self_param = false;
         if let Some(param_list) = src.value.param_list() {
             if let Some(self_param) = param_list.self_param() {
                 let self_type = if let Some(type_ref) = self_param.ascribed_type() {
-                    TypeRef::from_ast(type_ref)
+                    TypeRef::from_ast(&ctx, type_ref)
                 } else {
                     let self_type = TypeRef::Path(name![Self].into());
                     match self_param.kind() {
@@ -63,14 +65,14 @@ impl FunctionData {
                 has_self_param = true;
             }
             for param in param_list.params() {
-                let type_ref = TypeRef::from_ast_opt(param.ascribed_type());
+                let type_ref = TypeRef::from_ast_opt(&ctx, param.ascribed_type());
                 params.push(type_ref);
             }
         }
         let attrs = Attrs::new(&src.value, &Hygiene::new(db.upcast(), src.file_id));
 
         let ret_type = if let Some(type_ref) = src.value.ret_type().and_then(|rt| rt.type_ref()) {
-            TypeRef::from_ast(type_ref)
+            TypeRef::from_ast(&ctx, type_ref)
         } else {
             TypeRef::unit()
         };
@@ -122,7 +124,8 @@ impl TypeAliasData {
         let loc = typ.lookup(db);
         let node = loc.source(db);
         let name = node.value.name().map_or_else(Name::missing, |n| n.as_name());
-        let type_ref = node.value.type_ref().map(TypeRef::from_ast);
+        let lower_ctx = LowerCtx::new(db, node.file_id);
+        let type_ref = node.value.type_ref().map(|it| TypeRef::from_ast(&lower_ctx, it));
         let vis_default = RawVisibility::default_for_container(loc.container);
         let visibility = RawVisibility::from_ast_with_default(
             db,
@@ -130,7 +133,7 @@ impl TypeAliasData {
             node.as_ref().map(|n| n.visibility()),
         );
         let bounds = if let Some(bound_list) = node.value.type_bound_list() {
-            bound_list.bounds().map(TypeBound::from_ast).collect()
+            bound_list.bounds().map(|it| TypeBound::from_ast(&lower_ctx, it)).collect()
         } else {
             Vec::new()
         };
@@ -223,9 +226,10 @@ impl ImplData {
         let _p = profile("impl_data_query");
         let impl_loc = id.lookup(db);
         let src = impl_loc.source(db);
+        let lower_ctx = LowerCtx::new(db, src.file_id);
 
-        let target_trait = src.value.target_trait().map(TypeRef::from_ast);
-        let target_type = TypeRef::from_ast_opt(src.value.target_type());
+        let target_trait = src.value.target_trait().map(|it| TypeRef::from_ast(&lower_ctx, it));
+        let target_type = TypeRef::from_ast_opt(&lower_ctx, src.value.target_type());
         let is_negative = src.value.excl_token().is_some();
         let module_id = impl_loc.container.module(db);
 
@@ -279,8 +283,9 @@ impl ConstData {
         vis_default: RawVisibility,
         node: InFile<N>,
     ) -> ConstData {
+        let ctx = LowerCtx::new(db, node.file_id);
         let name = node.value.name().map(|n| n.as_name());
-        let type_ref = TypeRef::from_ast_opt(node.value.ascribed_type());
+        let type_ref = TypeRef::from_ast_opt(&ctx, node.value.ascribed_type());
         let visibility =
             RawVisibility::from_ast_with_default(db, vis_default, node.map(|n| n.visibility()));
         ConstData { name, type_ref, visibility }
diff --git a/crates/ra_hir_def/src/generics.rs b/crates/ra_hir_def/src/generics.rs
index d850244c4..09a5241f7 100644
--- a/crates/ra_hir_def/src/generics.rs
+++ b/crates/ra_hir_def/src/generics.rs
@@ -15,6 +15,7 @@ use ra_prof::profile;
 use ra_syntax::ast::{self, NameOwner, TypeBoundsOwner, TypeParamsOwner};
 
 use crate::{
+    body::LowerCtx,
     child_by_source::ChildBySource,
     db::DefDatabase,
     dyn_map::DynMap,
@@ -80,11 +81,13 @@ impl GenericParams {
     fn new(db: &dyn DefDatabase, def: GenericDefId) -> (GenericParams, InFile<SourceMap>) {
         let mut generics = GenericParams { types: Arena::default(), where_predicates: Vec::new() };
         let mut sm = ArenaMap::default();
+
         // FIXME: add `: Sized` bound for everything except for `Self` in traits
         let file_id = match def {
             GenericDefId::FunctionId(it) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 // lower `impl Trait` in arguments
                 let data = db.function_data(it);
                 for param in &data.params {
@@ -94,21 +97,25 @@ impl GenericParams {
             }
             GenericDefId::AdtId(AdtId::StructId(it)) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             GenericDefId::AdtId(AdtId::UnionId(it)) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             GenericDefId::AdtId(AdtId::EnumId(it)) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             GenericDefId::TraitId(it) => {
                 let src = it.lookup(db).source(db);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
 
                 // traits get the Self type as an implicit first type parameter
                 let self_param_id = generics.types.alloc(TypeParamData {
@@ -120,14 +127,16 @@ impl GenericParams {
                 // add super traits as bounds on Self
                 // i.e., trait Foo: Bar is equivalent to trait Foo where Self: Bar
                 let self_param = TypeRef::Path(name![Self].into());
-                generics.fill_bounds(&src.value, self_param);
+                generics.fill_bounds(&lower_ctx, &src.value, self_param);
 
-                generics.fill(&mut sm, &src.value);
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             GenericDefId::TypeAliasId(it) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             // Note that we don't add `Self` here: in `impl`s, `Self` is not a
@@ -135,7 +144,9 @@ impl GenericParams {
             // type, so this is handled by the resolver.
             GenericDefId::ImplId(it) => {
                 let src = it.lookup(db).source(db);
-                generics.fill(&mut sm, &src.value);
+                let lower_ctx = LowerCtx::new(db, src.file_id);
+
+                generics.fill(&lower_ctx, &mut sm, &src.value);
                 src.file_id
             }
             // We won't be using this ID anyway
@@ -145,28 +156,38 @@ impl GenericParams {
         (generics, InFile::new(file_id, sm))
     }
 
-    fn fill(&mut self, sm: &mut SourceMap, node: &dyn TypeParamsOwner) {
+    fn fill(&mut self, lower_ctx: &LowerCtx, sm: &mut SourceMap, node: &dyn TypeParamsOwner) {
         if let Some(params) = node.type_param_list() {
-            self.fill_params(sm, params)
+            self.fill_params(lower_ctx, sm, params)
         }
         if let Some(where_clause) = node.where_clause() {
-            self.fill_where_predicates(where_clause);
+            self.fill_where_predicates(lower_ctx, where_clause);
         }
     }
 
-    fn fill_bounds(&mut self, node: &dyn ast::TypeBoundsOwner, type_ref: TypeRef) {
+    fn fill_bounds(
+        &mut self,
+        lower_ctx: &LowerCtx,
+        node: &dyn ast::TypeBoundsOwner,
+        type_ref: TypeRef,
+    ) {
         for bound in
             node.type_bound_list().iter().flat_map(|type_bound_list| type_bound_list.bounds())
         {
-            self.add_where_predicate_from_bound(bound, type_ref.clone());
+            self.add_where_predicate_from_bound(lower_ctx, bound, type_ref.clone());
         }
     }
 
-    fn fill_params(&mut self, sm: &mut SourceMap, params: ast::TypeParamList) {
+    fn fill_params(
+        &mut self,
+        lower_ctx: &LowerCtx,
+        sm: &mut SourceMap,
+        params: ast::TypeParamList,
+    ) {
         for type_param in params.type_params() {
             let name = type_param.name().map_or_else(Name::missing, |it| it.as_name());
             // FIXME: Use `Path::from_src`
-            let default = type_param.default_type().map(TypeRef::from_ast);
+            let default = type_param.default_type().map(|it| TypeRef::from_ast(lower_ctx, it));
             let param = TypeParamData {
                 name: Some(name.clone()),
                 default,
@@ -176,29 +197,34 @@ impl GenericParams {
             sm.insert(param_id, Either::Right(type_param.clone()));
 
             let type_ref = TypeRef::Path(name.into());
-            self.fill_bounds(&type_param, type_ref);
+            self.fill_bounds(&lower_ctx, &type_param, type_ref);
         }
     }
 
-    fn fill_where_predicates(&mut self, where_clause: ast::WhereClause) {
+    fn fill_where_predicates(&mut self, lower_ctx: &LowerCtx, where_clause: ast::WhereClause) {
         for pred in where_clause.predicates() {
             let type_ref = match pred.type_ref() {
                 Some(type_ref) => type_ref,
                 None => continue,
             };
-            let type_ref = TypeRef::from_ast(type_ref);
+            let type_ref = TypeRef::from_ast(lower_ctx, type_ref);
             for bound in pred.type_bound_list().iter().flat_map(|l| l.bounds()) {
-                self.add_where_predicate_from_bound(bound, type_ref.clone());
+                self.add_where_predicate_from_bound(lower_ctx, bound, type_ref.clone());
             }
         }
     }
 
-    fn add_where_predicate_from_bound(&mut self, bound: ast::TypeBound, type_ref: TypeRef) {
+    fn add_where_predicate_from_bound(
+        &mut self,
+        lower_ctx: &LowerCtx,
+        bound: ast::TypeBound,
+        type_ref: TypeRef,
+    ) {
         if bound.question_token().is_some() {
             // FIXME: remove this bound
             return;
         }
-        let bound = TypeBound::from_ast(bound);
+        let bound = TypeBound::from_ast(lower_ctx, bound);
         self.where_predicates
             .push(WherePredicate { target: WherePredicateTarget::TypeRef(type_ref), bound });
     }
diff --git a/crates/ra_hir_def/src/path.rs b/crates/ra_hir_def/src/path.rs
index 162b3c8c7..e84efe2ab 100644
--- a/crates/ra_hir_def/src/path.rs
+++ b/crates/ra_hir_def/src/path.rs
@@ -7,6 +7,7 @@ use std::{
     sync::Arc,
 };
 
+use crate::body::LowerCtx;
 use hir_expand::{
     hygiene::Hygiene,
     name::{AsName, Name},
@@ -244,8 +245,8 @@ impl<'a> PathSegments<'a> {
 }
 
 impl GenericArgs {
-    pub(crate) fn from_ast(node: ast::TypeArgList) -> Option<GenericArgs> {
-        lower::lower_generic_args(node)
+    pub(crate) fn from_ast(lower_ctx: &LowerCtx, node: ast::TypeArgList) -> Option<GenericArgs> {
+        lower::lower_generic_args(lower_ctx, node)
     }
 
     pub(crate) fn empty() -> GenericArgs {
diff --git a/crates/ra_hir_def/src/path/lower.rs b/crates/ra_hir_def/src/path/lower.rs
index 9ec2e0dcd..e3d237a0a 100644
--- a/crates/ra_hir_def/src/path/lower.rs
+++ b/crates/ra_hir_def/src/path/lower.rs
@@ -13,6 +13,7 @@ use ra_syntax::ast::{self, AstNode, TypeAscriptionOwner, TypeBoundsOwner};
 
 use super::AssociatedTypeBinding;
 use crate::{
+    body::LowerCtx,
     path::{GenericArg, GenericArgs, ModPath, Path, PathKind},
     type_ref::{TypeBound, TypeRef},
 };
@@ -26,6 +27,7 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
     let mut type_anchor = None;
     let mut segments = Vec::new();
     let mut generic_args = Vec::new();
+    let ctx = LowerCtx::with_hygiene(hygiene);
     loop {
         let segment = path.segment()?;
 
@@ -40,9 +42,10 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
                     Either::Left(name) => {
                         let args = segment
                             .type_arg_list()
-                            .and_then(lower_generic_args)
+                            .and_then(|it| lower_generic_args(&ctx, it))
                             .or_else(|| {
                                 lower_generic_args_from_fn_path(
+                                    &ctx,
                                     segment.param_list(),
                                     segment.ret_type(),
                                 )
@@ -60,7 +63,7 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
             ast::PathSegmentKind::Type { type_ref, trait_ref } => {
                 assert!(path.qualifier().is_none()); // this can only occur at the first segment
 
-                let self_type = TypeRef::from_ast(type_ref?);
+                let self_type = TypeRef::from_ast(&ctx, type_ref?);
 
                 match trait_ref {
                     // <T>::foo
@@ -128,10 +131,13 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
     }
 }
 
-pub(super) fn lower_generic_args(node: ast::TypeArgList) -> Option<GenericArgs> {
+pub(super) fn lower_generic_args(
+    lower_ctx: &LowerCtx,
+    node: ast::TypeArgList,
+) -> Option<GenericArgs> {
     let mut args = Vec::new();
     for type_arg in node.type_args() {
-        let type_ref = TypeRef::from_ast_opt(type_arg.type_ref());
+        let type_ref = TypeRef::from_ast_opt(lower_ctx, type_arg.type_ref());
         args.push(GenericArg::Type(type_ref));
     }
     // lifetimes ignored for now
@@ -140,9 +146,9 @@ pub(super) fn lower_generic_args(node: ast::TypeArgList) -> Option<GenericArgs>
         let assoc_type_arg: ast::AssocTypeArg = assoc_type_arg;
         if let Some(name_ref) = assoc_type_arg.name_ref() {
             let name = name_ref.as_name();
-            let type_ref = assoc_type_arg.type_ref().map(TypeRef::from_ast);
+            let type_ref = assoc_type_arg.type_ref().map(|it| TypeRef::from_ast(lower_ctx, it));
             let bounds = if let Some(l) = assoc_type_arg.type_bound_list() {
-                l.bounds().map(TypeBound::from_ast).collect()
+                l.bounds().map(|it| TypeBound::from_ast(lower_ctx, it)).collect()
             } else {
                 Vec::new()
             };
@@ -159,6 +165,7 @@ pub(super) fn lower_generic_args(node: ast::TypeArgList) -> Option<GenericArgs>
 /// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
 /// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
 fn lower_generic_args_from_fn_path(
+    ctx: &LowerCtx,
     params: Option<ast::ParamList>,
     ret_type: Option<ast::RetType>,
 ) -> Option<GenericArgs> {
@@ -167,14 +174,14 @@ fn lower_generic_args_from_fn_path(
     if let Some(params) = params {
         let mut param_types = Vec::new();
         for param in params.params() {
-            let type_ref = TypeRef::from_ast_opt(param.ascribed_type());
+            let type_ref = TypeRef::from_ast_opt(&ctx, param.ascribed_type());
             param_types.push(type_ref);
         }
         let arg = GenericArg::Type(TypeRef::Tuple(param_types));
         args.push(arg);
     }
     if let Some(ret_type) = ret_type {
-        let type_ref = TypeRef::from_ast_opt(ret_type.type_ref());
+        let type_ref = TypeRef::from_ast_opt(&ctx, ret_type.type_ref());
         bindings.push(AssociatedTypeBinding {
             name: name![Output],
             type_ref: Some(type_ref),
diff --git a/crates/ra_hir_def/src/type_ref.rs b/crates/ra_hir_def/src/type_ref.rs
index f308c6bdf..5bdad9efd 100644
--- a/crates/ra_hir_def/src/type_ref.rs
+++ b/crates/ra_hir_def/src/type_ref.rs
@@ -3,7 +3,7 @@
 
 use ra_syntax::ast::{self, TypeAscriptionOwner, TypeBoundsOwner};
 
-use crate::path::Path;
+use crate::{body::LowerCtx, path::Path};
 
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub enum Mutability {
@@ -64,30 +64,34 @@ pub enum TypeBound {
 
 impl TypeRef {
     /// Converts an `ast::TypeRef` to a `hir::TypeRef`.
-    pub(crate) fn from_ast(node: ast::TypeRef) -> Self {
+    pub(crate) fn from_ast(ctx: &LowerCtx, node: ast::TypeRef) -> Self {
         match node {
-            ast::TypeRef::ParenType(inner) => TypeRef::from_ast_opt(inner.type_ref()),
+            ast::TypeRef::ParenType(inner) => TypeRef::from_ast_opt(&ctx, inner.type_ref()),
             ast::TypeRef::TupleType(inner) => {
-                TypeRef::Tuple(inner.fields().map(TypeRef::from_ast).collect())
+                TypeRef::Tuple(inner.fields().map(|it| TypeRef::from_ast(ctx, it)).collect())
             }
             ast::TypeRef::NeverType(..) => TypeRef::Never,
             ast::TypeRef::PathType(inner) => {
                 // FIXME: Use `Path::from_src`
-                inner.path().and_then(Path::from_ast).map(TypeRef::Path).unwrap_or(TypeRef::Error)
+                inner
+                    .path()
+                    .and_then(|it| ctx.lower_path(it))
+                    .map(TypeRef::Path)
+                    .unwrap_or(TypeRef::Error)
             }
             ast::TypeRef::PointerType(inner) => {
-                let inner_ty = TypeRef::from_ast_opt(inner.type_ref());
+                let inner_ty = TypeRef::from_ast_opt(&ctx, inner.type_ref());
                 let mutability = Mutability::from_mutable(inner.mut_token().is_some());
                 TypeRef::RawPtr(Box::new(inner_ty), mutability)
             }
             ast::TypeRef::ArrayType(inner) => {
-                TypeRef::Array(Box::new(TypeRef::from_ast_opt(inner.type_ref())))
+                TypeRef::Array(Box::new(TypeRef::from_ast_opt(&ctx, inner.type_ref())))
             }
             ast::TypeRef::SliceType(inner) => {
-                TypeRef::Slice(Box::new(TypeRef::from_ast_opt(inner.type_ref())))
+                TypeRef::Slice(Box::new(TypeRef::from_ast_opt(&ctx, inner.type_ref())))
             }
             ast::TypeRef::ReferenceType(inner) => {
-                let inner_ty = TypeRef::from_ast_opt(inner.type_ref());
+                let inner_ty = TypeRef::from_ast_opt(&ctx, inner.type_ref());
                 let mutability = Mutability::from_mutable(inner.mut_token().is_some());
                 TypeRef::Reference(Box::new(inner_ty), mutability)
             }
@@ -96,10 +100,13 @@ impl TypeRef {
                 let ret_ty = inner
                     .ret_type()
                     .and_then(|rt| rt.type_ref())
-                    .map(TypeRef::from_ast)
+                    .map(|it| TypeRef::from_ast(ctx, it))
                     .unwrap_or_else(|| TypeRef::Tuple(Vec::new()));
                 let mut params = if let Some(pl) = inner.param_list() {
-                    pl.params().map(|p| p.ascribed_type()).map(TypeRef::from_ast_opt).collect()
+                    pl.params()
+                        .map(|p| p.ascribed_type())
+                        .map(|it| TypeRef::from_ast_opt(&ctx, it))
+                        .collect()
                 } else {
                     Vec::new()
                 };
@@ -107,19 +114,19 @@ impl TypeRef {
                 TypeRef::Fn(params)
             }
             // for types are close enough for our purposes to the inner type for now...
-            ast::TypeRef::ForType(inner) => TypeRef::from_ast_opt(inner.type_ref()),
+            ast::TypeRef::ForType(inner) => TypeRef::from_ast_opt(&ctx, inner.type_ref()),
             ast::TypeRef::ImplTraitType(inner) => {
-                TypeRef::ImplTrait(type_bounds_from_ast(inner.type_bound_list()))
+                TypeRef::ImplTrait(type_bounds_from_ast(ctx, inner.type_bound_list()))
             }
             ast::TypeRef::DynTraitType(inner) => {
-                TypeRef::DynTrait(type_bounds_from_ast(inner.type_bound_list()))
+                TypeRef::DynTrait(type_bounds_from_ast(ctx, inner.type_bound_list()))
             }
         }
     }
 
-    pub(crate) fn from_ast_opt(node: Option<ast::TypeRef>) -> Self {
+    pub(crate) fn from_ast_opt(ctx: &LowerCtx, node: Option<ast::TypeRef>) -> Self {
         if let Some(node) = node {
-            TypeRef::from_ast(node)
+            TypeRef::from_ast(ctx, node)
         } else {
             TypeRef::Error
         }
@@ -180,24 +187,27 @@ impl TypeRef {
     }
 }
 
-pub(crate) fn type_bounds_from_ast(type_bounds_opt: Option<ast::TypeBoundList>) -> Vec<TypeBound> {
+pub(crate) fn type_bounds_from_ast(
+    lower_ctx: &LowerCtx,
+    type_bounds_opt: Option<ast::TypeBoundList>,
+) -> Vec<TypeBound> {
     if let Some(type_bounds) = type_bounds_opt {
-        type_bounds.bounds().map(TypeBound::from_ast).collect()
+        type_bounds.bounds().map(|it| TypeBound::from_ast(lower_ctx, it)).collect()
     } else {
         vec![]
     }
 }
 
 impl TypeBound {
-    pub(crate) fn from_ast(node: ast::TypeBound) -> Self {
+    pub(crate) fn from_ast(ctx: &LowerCtx, node: ast::TypeBound) -> Self {
         match node.kind() {
             ast::TypeBoundKind::PathType(path_type) => {
                 let path = match path_type.path() {
                     Some(p) => p,
                     None => return TypeBound::Error,
                 };
-                // FIXME: Use `Path::from_src`
-                let path = match Path::from_ast(path) {
+
+                let path = match ctx.lower_path(path) {
                     Some(p) => p,
                     None => return TypeBound::Error,
                 };
diff --git a/crates/ra_hir_expand/src/hygiene.rs b/crates/ra_hir_expand/src/hygiene.rs
index 0b41d0e95..53866bbcb 100644
--- a/crates/ra_hir_expand/src/hygiene.rs
+++ b/crates/ra_hir_expand/src/hygiene.rs
@@ -12,7 +12,7 @@ use crate::{
     HirFileId, HirFileIdRepr, MacroCallId, MacroDefKind,
 };
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct Hygiene {
     // This is what `$crate` expands to
     def_crate: Option<CrateId>,