5 files changed, 77 insertions, 17 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index fb788736d..af59aa1b6 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -953,6 +953,16 @@ impl TypeParam {
     pub fn module(self, db: &dyn HirDatabase) -> Module {
         self.id.parent.module(db.upcast()).into()
     }
+
+    pub fn ty(self, db: &dyn HirDatabase) -> Type {
+        let resolver = self.id.parent.resolver(db.upcast());
+        let environment = TraitEnvironment::lower(db, &resolver);
+        let ty = Ty::Placeholder(self.id);
+        Type {
+            krate: self.id.parent.module(db.upcast()).krate,
+            ty: InEnvironment { value: ty, environment },
+        }
+    }
 }
 
 // FIXME: rename from `ImplDef` to `Impl`
@@ -1157,18 +1167,21 @@ impl Type {
 
     pub fn fields(&self, db: &dyn HirDatabase) -> Vec<(Field, Type)> {
         if let Ty::Apply(a_ty) = &self.ty.value {
-            if let TypeCtor::Adt(AdtId::StructId(s)) = a_ty.ctor {
-                let var_def = s.into();
-                return db
-                    .field_types(var_def)
-                    .iter()
-                    .map(|(local_id, ty)| {
-                        let def = Field { parent: var_def.into(), id: local_id };
-                        let ty = ty.clone().subst(&a_ty.parameters);
-                        (def, self.derived(ty))
-                    })
-                    .collect();
-            }
+            let variant_id = match a_ty.ctor {
+                TypeCtor::Adt(AdtId::StructId(s)) => s.into(),
+                TypeCtor::Adt(AdtId::UnionId(u)) => u.into(),
+                _ => return Vec::new(),
+            };
+
+            return db
+                .field_types(variant_id)
+                .iter()
+                .map(|(local_id, ty)| {
+                    let def = Field { parent: variant_id.into(), id: local_id };
+                    let ty = ty.clone().subst(&a_ty.parameters);
+                    (def, self.derived(ty))
+                })
+                .collect();
         };
         Vec::new()
     }
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/semantics.rs b/crates/ra_hir/src/semantics.rs
index 86bfb416c..515e5eb17 100644
--- a/crates/ra_hir/src/semantics.rs
+++ b/crates/ra_hir/src/semantics.rs
@@ -8,7 +8,8 @@ use hir_def::{
     resolver::{self, HasResolver, Resolver},
     AsMacroCall, TraitId,
 };
-use hir_expand::ExpansionInfo;
+use hir_expand::{hygiene::Hygiene, ExpansionInfo};
+use hir_ty::associated_type_shorthand_candidates;
 use itertools::Itertools;
 use ra_db::{FileId, FileRange};
 use ra_prof::profile;
@@ -24,8 +25,9 @@ use crate::{
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
     AssocItem, Field, Function, HirFileId, ImplDef, InFile, Local, MacroDef, Module, ModuleDef,
-    Name, Origin, Path, ScopeDef, Trait, Type, TypeParam,
+    Name, Origin, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam,
 };
+use resolver::TypeNs;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum PathResolution {
@@ -40,6 +42,44 @@ pub enum PathResolution {
     AssocItem(AssocItem),
 }
 
+impl PathResolution {
+    fn in_type_ns(&self) -> Option<TypeNs> {
+        match self {
+            PathResolution::Def(ModuleDef::Adt(adt)) => Some(TypeNs::AdtId((*adt).into())),
+            PathResolution::Def(ModuleDef::BuiltinType(builtin)) => {
+                Some(TypeNs::BuiltinType(*builtin))
+            }
+            PathResolution::Def(ModuleDef::Const(_))
+            | PathResolution::Def(ModuleDef::EnumVariant(_))
+            | PathResolution::Def(ModuleDef::Function(_))
+            | PathResolution::Def(ModuleDef::Module(_))
+            | PathResolution::Def(ModuleDef::Static(_))
+            | PathResolution::Def(ModuleDef::Trait(_)) => None,
+            PathResolution::Def(ModuleDef::TypeAlias(alias)) => {
+                Some(TypeNs::TypeAliasId((*alias).into()))
+            }
+            PathResolution::Local(_) | PathResolution::Macro(_) => None,
+            PathResolution::TypeParam(param) => Some(TypeNs::GenericParam((*param).into())),
+            PathResolution::SelfType(impl_def) => Some(TypeNs::SelfType((*impl_def).into())),
+            PathResolution::AssocItem(AssocItem::Const(_))
+            | PathResolution::AssocItem(AssocItem::Function(_)) => None,
+            PathResolution::AssocItem(AssocItem::TypeAlias(alias)) => {
+                Some(TypeNs::TypeAliasId((*alias).into()))
+            }
+        }
+    }
+
+    /// Returns an iterator over associated types that may be specified after this path (using
+    /// `Ty::Assoc` syntax).
+    pub fn assoc_type_shorthand_candidates<R>(
+        &self,
+        db: &dyn HirDatabase,
+        mut cb: impl FnMut(TypeAlias) -> Option<R>,
+    ) -> Option<R> {
+        associated_type_shorthand_candidates(db, self.in_type_ns()?, |_, _, id| cb(id.into()))
+    }
+}
+
 /// Primary API to get semantic information, like types, from syntax trees.
 pub struct Semantics<'db, DB> {
     pub db: &'db DB,
@@ -206,6 +246,11 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.analyze(path.syntax()).resolve_path(self.db, path)
     }
 
+    pub 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> {
         self.analyze(pat.syntax()).resolve_bind_pat_to_const(self.db, pat)
     }
diff --git a/crates/ra_hir/src/semantics/source_to_def.rs b/crates/ra_hir/src/semantics/source_to_def.rs
index 6f3b5b2da..8af64fdc1 100644
--- a/crates/ra_hir/src/semantics/source_to_def.rs
+++ b/crates/ra_hir/src/semantics/source_to_def.rs
@@ -151,7 +151,7 @@ impl SourceToDefCtx<'_, '_> {
         let krate = self.file_to_def(file_id)?.krate;
         let file_ast_id = self.db.ast_id_map(src.file_id).ast_id(&src.value);
         let ast_id = Some(AstId::new(src.file_id, file_ast_id));
-        Some(MacroDefId { krate: Some(krate), ast_id, kind })
+        Some(MacroDefId { krate: Some(krate), ast_id, kind, local_inner: false })
     }
 
     pub(super) fn find_container(&mut self, src: InFile<&SyntaxNode>) -> Option<ChildContainer> {
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)
     }