4 files changed, 103 insertions, 40 deletions

diff --git a/crates/ra_hir/src/adt.rs b/crates/ra_hir/src/adt.rs
index ec6a10353..22bbad964 100644
--- a/crates/ra_hir/src/adt.rs
+++ b/crates/ra_hir/src/adt.rs
@@ -11,7 +11,7 @@ use ra_syntax::{
 
 use crate::{
     Name, AsName, Struct, Enum, EnumVariant, Crate,
-    HirDatabase, HirFileId,
+    HirDatabase, HirFileId, StructField, FieldSource,
     type_ref::TypeRef,
 };
 
@@ -150,7 +150,7 @@ impl VariantData {
 impl VariantData {
     fn new(flavor: StructFlavor) -> Self {
         let inner = match flavor {
-            StructFlavor::Tuple(fl) => {
+            ast::StructFlavor::Tuple(fl) => {
                 let fields = fl
                     .fields()
                     .enumerate()
@@ -161,7 +161,7 @@ impl VariantData {
                     .collect();
                 VariantDataInner::Tuple(fields)
             }
-            StructFlavor::Named(fl) => {
+            ast::StructFlavor::Named(fl) => {
                 let fields = fl
                     .fields()
                     .map(|fd| StructFieldData {
@@ -171,8 +171,70 @@ impl VariantData {
                     .collect();
                 VariantDataInner::Struct(fields)
             }
-            StructFlavor::Unit => VariantDataInner::Unit,
+            ast::StructFlavor::Unit => VariantDataInner::Unit,
         };
         VariantData(inner)
     }
 }
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum VariantDef {
+    Struct(Struct),
+    EnumVariant(EnumVariant),
+}
+impl_froms!(VariantDef: Struct, EnumVariant);
+
+impl VariantDef {
+    pub(crate) fn field(self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
+        match self {
+            VariantDef::Struct(it) => it.field(db, name),
+            VariantDef::EnumVariant(it) => it.field(db, name),
+        }
+    }
+    pub(crate) fn variant_data(self, db: &impl HirDatabase) -> Arc<VariantData> {
+        match self {
+            VariantDef::Struct(it) => it.variant_data(db),
+            VariantDef::EnumVariant(it) => it.variant_data(db),
+        }
+    }
+}
+
+impl StructField {
+    pub(crate) fn source_impl(&self, db: &impl HirDatabase) -> (HirFileId, FieldSource) {
+        let var_data = self.parent.variant_data(db);
+        let fields = var_data.fields().unwrap();
+        let ss;
+        let es;
+        let (file_id, struct_flavor) = match self.parent {
+            VariantDef::Struct(s) => {
+                let (file_id, source) = s.source(db);
+                ss = source;
+                (file_id, ss.flavor())
+            }
+            VariantDef::EnumVariant(e) => {
+                let (file_id, source) = e.source(db);
+                es = source;
+                (file_id, es.flavor())
+            }
+        };
+
+        let field_sources = match struct_flavor {
+            ast::StructFlavor::Tuple(fl) => fl
+                .fields()
+                .map(|it| FieldSource::Pos(it.to_owned()))
+                .collect(),
+            ast::StructFlavor::Named(fl) => fl
+                .fields()
+                .map(|it| FieldSource::Named(it.to_owned()))
+                .collect(),
+            ast::StructFlavor::Unit => Vec::new(),
+        };
+        let field = field_sources
+            .into_iter()
+            .zip(fields.iter())
+            .find(|(_syntax, (id, _))| *id == self.id)
+            .unwrap()
+            .0;
+        (file_id, field)
+    }
+}
diff --git a/crates/ra_hir/src/code_model_api.rs b/crates/ra_hir/src/code_model_api.rs
index 118562984..fdea5be57 100644
--- a/crates/ra_hir/src/code_model_api.rs
+++ b/crates/ra_hir/src/code_model_api.rs
@@ -10,8 +10,8 @@ use crate::{
     nameres::{ModuleScope, lower::ImportId},
     db::HirDatabase,
     expr::BodySyntaxMapping,
-    ty::{InferenceResult, VariantDef},
-    adt::{EnumVariantId, StructFieldId},
+    ty::InferenceResult,
+    adt::{EnumVariantId, StructFieldId, VariantDef},
     generics::GenericParams,
     docs::{Documentation, Docs, docs_from_ast},
     module_tree::ModuleId,
@@ -179,10 +179,16 @@ impl Module {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct StructField {
-    parent: VariantDef,
+    pub(crate) parent: VariantDef,
     pub(crate) id: StructFieldId,
 }
 
+#[derive(Debug)]
+pub enum FieldSource {
+    Named(TreeArc<ast::NamedFieldDef>),
+    Pos(TreeArc<ast::PosField>),
+}
+
 impl StructField {
     pub fn name(&self, db: &impl HirDatabase) -> Name {
         self.parent.variant_data(db).fields().unwrap()[self.id]
@@ -190,6 +196,10 @@ impl StructField {
             .clone()
     }
 
+    pub fn source(&self, db: &impl HirDatabase) -> (HirFileId, FieldSource) {
+        self.source_impl(db)
+    }
+
     pub fn ty(&self, db: &impl HirDatabase) -> Ty {
         db.type_for_field(*self)
     }
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 596f9c38c..eaf8565ee 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -68,7 +68,7 @@ pub use self::code_model_api::{
     Module, ModuleDef, ModuleSource, Problem,
     Struct, Enum, EnumVariant,
     Function, FnSignature, ScopeEntryWithSyntax,
-    StructField,
+    StructField, FieldSource,
     Static, Const,
     Trait, Type,
 };
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index c57e222dd..714eaaae5 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -38,7 +38,7 @@ use crate::{
     expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat},
     generics::GenericParams,
     path::GenericArg,
-    adt::VariantData,
+    adt::VariantDef,
 };
 
 /// The ID of a type variable.
@@ -696,28 +696,6 @@ pub(super) fn type_for_def(db: &impl HirDatabase, def: TypableDef) -> Ty {
     }
 }
 
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
-pub enum VariantDef {
-    Struct(Struct),
-    EnumVariant(EnumVariant),
-}
-impl_froms!(VariantDef: Struct, EnumVariant);
-
-impl VariantDef {
-    pub(crate) fn field(self, db: &impl HirDatabase, name: &Name) -> Option<StructField> {
-        match self {
-            VariantDef::Struct(it) => it.field(db, name),
-            VariantDef::EnumVariant(it) => it.field(db, name),
-        }
-    }
-    pub(crate) fn variant_data(self, db: &impl HirDatabase) -> Arc<VariantData> {
-        match self {
-            VariantDef::Struct(it) => it.variant_data(db),
-            VariantDef::EnumVariant(it) => it.variant_data(db),
-        }
-    }
-}
-
 pub(super) fn type_for_field(db: &impl HirDatabase, field: StructField) -> Ty {
     let parent_def = field.parent_def(db);
     let (generics, module) = match parent_def {
@@ -732,8 +710,10 @@ pub(super) fn type_for_field(db: &impl HirDatabase, field: StructField) -> Ty {
 /// The result of type inference: A mapping from expressions and patterns to types.
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct InferenceResult {
-    /// For each method call expr, record the function it resolved to.
+    /// For each method call expr, records the function it resolves to.
     method_resolutions: FxHashMap<ExprId, Function>,
+    /// For each field access expr, records the field it resolves to.
+    field_resolutions: FxHashMap<ExprId, StructField>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
 }
@@ -742,6 +722,9 @@ impl InferenceResult {
     pub fn method_resolution(&self, expr: ExprId) -> Option<Function> {
         self.method_resolutions.get(&expr).map(|it| *it)
     }
+    pub fn field_resolution(&self, expr: ExprId) -> Option<StructField> {
+        self.field_resolutions.get(&expr).map(|it| *it)
+    }
 }
 
 impl Index<ExprId> for InferenceResult {
@@ -770,6 +753,7 @@ struct InferenceContext<'a, D: HirDatabase> {
     impl_block: Option<ImplBlock>,
     var_unification_table: InPlaceUnificationTable<TypeVarId>,
     method_resolutions: FxHashMap<ExprId, Function>,
+    field_resolutions: FxHashMap<ExprId, StructField>,
     type_of_expr: ArenaMap<ExprId, Ty>,
     type_of_pat: ArenaMap<PatId, Ty>,
     /// The return type of the function being inferred.
@@ -861,6 +845,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     ) -> Self {
         InferenceContext {
             method_resolutions: FxHashMap::default(),
+            field_resolutions: FxHashMap::default(),
             type_of_expr: ArenaMap::default(),
             type_of_pat: ArenaMap::default(),
             var_unification_table: InPlaceUnificationTable::new(),
@@ -886,6 +871,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         }
         InferenceResult {
             method_resolutions: mem::replace(&mut self.method_resolutions, Default::default()),
+            field_resolutions: mem::replace(&mut self.field_resolutions, Default::default()),
             type_of_expr: expr_types,
             type_of_pat: pat_types,
         }
@@ -899,6 +885,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         self.method_resolutions.insert(expr, func);
     }
 
+    fn write_field_resolution(&mut self, expr: ExprId, field: StructField) {
+        self.field_resolutions.insert(expr, field);
+    }
+
     fn write_pat_ty(&mut self, pat: PatId, ty: Ty) {
         self.type_of_pat.insert(pat, ty);
     }
@@ -1251,9 +1241,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         ty
     }
 
-    fn infer_expr(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
+    fn infer_expr(&mut self, tgt_expr: ExprId, expected: &Expectation) -> Ty {
         let body = Arc::clone(&self.body); // avoid borrow checker problem
-        let ty = match &body[expr] {
+        let ty = match &body[tgt_expr] {
             Expr::Missing => Ty::Unknown,
             Expr::If {
                 condition,
@@ -1344,7 +1334,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let resolved = receiver_ty.clone().lookup_method(self.db, method_name);
                 let method_ty = match resolved {
                     Some(func) => {
-                        self.write_method_resolution(expr, func);
+                        self.write_method_resolution(tgt_expr, func);
                         self.db.type_for_def(func.into())
                     }
                     None => Ty::Unknown,
@@ -1389,7 +1379,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 expected.ty
             }
-            Expr::Path(p) => self.infer_path_expr(expr, p).unwrap_or(Ty::Unknown),
+            Expr::Path(p) => self.infer_path_expr(tgt_expr, p).unwrap_or(Ty::Unknown),
             Expr::Continue => Ty::Never,
             Expr::Break { expr } => {
                 if let Some(expr) = expr {
@@ -1436,9 +1426,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                             def_id: AdtDef::Struct(s),
                             ref substs,
                             ..
-                        } => s
-                            .field(self.db, name)
-                            .map(|field| field.ty(self.db).subst(substs)),
+                        } => s.field(self.db, name).map(|field| {
+                            self.write_field_resolution(tgt_expr, field);
+                            field.ty(self.db).subst(substs)
+                        }),
                         _ => None,
                     })
                     .unwrap_or(Ty::Unknown);
@@ -1545,7 +1536,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let ty = self.insert_type_vars_shallow(ty);
         self.unify(&ty, &expected.ty);
         let ty = self.resolve_ty_as_possible(ty);
-        self.write_expr_ty(expr, ty.clone());
+        self.write_expr_ty(tgt_expr, ty.clone());
         ty
     }