1 files changed, 24 insertions, 7 deletions

diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index cca59538a..d94e8154b 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -37,8 +37,8 @@ use crate::{
     code_model::{ModuleDef::Trait, TypeAlias},
     diagnostics::DiagnosticSink,
     expr::{
-        self, Array, BinaryOp, BindingAnnotation, Body, Expr, ExprId, FieldPat, Literal, Pat,
-        PatId, Statement, UnaryOp,
+        self, Array, BinaryOp, BindingAnnotation, Body, Expr, ExprId, Literal, Pat, PatId,
+        RecordFieldPat, Statement, UnaryOp,
     },
     generics::{GenericParams, HasGenericParams},
     name,
@@ -106,6 +106,13 @@ impl Default for BindingMode {
     }
 }
 
+/// A mismatch between an expected and an inferred type.
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub struct TypeMismatch {
+    pub expected: Ty,
+    pub actual: Ty,
+}
+
 /// The result of type inference: A mapping from expressions and patterns to types.
 #[derive(Clone, PartialEq, Eq, Debug, Default)]
 pub struct InferenceResult {
@@ -120,6 +127,7 @@ pub struct InferenceResult {
     diagnostics: Vec<InferenceDiagnostic>,
     pub(super) type_of_expr: ArenaMap<ExprId, Ty>,
     pub(super) type_of_pat: ArenaMap<PatId, Ty>,
+    pub(super) type_mismatches: ArenaMap<ExprId, TypeMismatch>,
 }
 
 impl InferenceResult {
@@ -141,6 +149,9 @@ impl InferenceResult {
     pub fn assoc_resolutions_for_pat(&self, id: PatId) -> Option<ImplItem> {
         self.assoc_resolutions.get(&id.into()).copied()
     }
+    pub fn type_mismatch_for_expr(&self, expr: ExprId) -> Option<&TypeMismatch> {
+        self.type_mismatches.get(expr)
+    }
     pub(crate) fn add_diagnostics(
         &self,
         db: &impl HirDatabase,
@@ -705,10 +716,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         ty
     }
 
-    fn infer_struct_pat(
+    fn infer_record_pat(
         &mut self,
         path: Option<&Path>,
-        subpats: &[FieldPat],
+        subpats: &[RecordFieldPat],
         expected: &Ty,
         default_bm: BindingMode,
         id: PatId,
@@ -800,7 +811,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm)
             }
             Pat::Struct { path: ref p, args: ref fields } => {
-                self.infer_struct_pat(p.as_ref(), fields, expected, default_bm, pat)
+                self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
             }
             Pat::Path(path) => {
                 // FIXME use correct resolver for the surrounding expression
@@ -1103,7 +1114,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 }
                 Ty::simple(TypeCtor::Never)
             }
-            Expr::StructLit { path, fields, spread } => {
+            Expr::RecordLit { path, fields, spread } => {
                 let (ty, def_id) = self.resolve_variant(path.as_ref());
                 if let Some(variant) = def_id {
                     self.write_variant_resolution(tgt_expr.into(), variant);
@@ -1345,9 +1356,15 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         };
         // use a new type variable if we got Ty::Unknown here
         let ty = self.insert_type_vars_shallow(ty);
-        self.unify(&ty, &expected.ty);
+        let could_unify = self.unify(&ty, &expected.ty);
         let ty = self.resolve_ty_as_possible(&mut vec![], ty);
         self.write_expr_ty(tgt_expr, ty.clone());
+        if !could_unify {
+            self.result.type_mismatches.insert(
+                tgt_expr,
+                TypeMismatch { expected: expected.ty.clone(), actual: ty.clone() },
+            );
+        }
         ty
     }