From 9c3f00a90651998c2cd4151f43f17cd92ef8eef1 Mon Sep 17 00:00:00 2001
From: Florian Diebold <florian.diebold@freiheit.com>
Date: Fri, 20 Dec 2019 18:27:51 +0100
Subject: [PATCH] Fix coercion of last expression in function body

---
 crates/ra_hir_ty/src/infer.rs          |  2 +-
 crates/ra_hir_ty/src/infer/expr.rs     |  2 +-
 crates/ra_hir_ty/src/tests/coercion.rs | 16 ++++++++++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/crates/ra_hir_ty/src/infer.rs b/crates/ra_hir_ty/src/infer.rs
index 9f2ed830ed..e97b814739 100644
--- a/crates/ra_hir_ty/src/infer.rs
+++ b/crates/ra_hir_ty/src/infer.rs
@@ -460,7 +460,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     }
 
     fn infer_body(&mut self) {
-        self.infer_expr(self.body.body_expr, &Expectation::has_type(self.return_ty.clone()));
+        self.infer_expr_coerce(self.body.body_expr, &Expectation::has_type(self.return_ty.clone()));
     }
 
     fn resolve_into_iter_item(&self) -> Option<TypeAliasId> {
diff --git a/crates/ra_hir_ty/src/infer/expr.rs b/crates/ra_hir_ty/src/infer/expr.rs
index 253332c30e..3af05394c6 100644
--- a/crates/ra_hir_ty/src/infer/expr.rs
+++ b/crates/ra_hir_ty/src/infer/expr.rs
@@ -41,7 +41,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
     /// Infer type of expression with possibly implicit coerce to the expected type.
     /// Return the type after possible coercion.
-    fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
+    pub(super) fn infer_expr_coerce(&mut self, expr: ExprId, expected: &Expectation) -> Ty {
         let ty = self.infer_expr_inner(expr, &expected);
         let ty = if !self.coerce(&ty, &expected.ty) {
             self.result
diff --git a/crates/ra_hir_ty/src/tests/coercion.rs b/crates/ra_hir_ty/src/tests/coercion.rs
index 33d6ca4034..793c23e41c 100644
--- a/crates/ra_hir_ty/src/tests/coercion.rs
+++ b/crates/ra_hir_ty/src/tests/coercion.rs
@@ -369,6 +369,22 @@ fn test() {
     );
 }
 
+#[test]
+fn return_coerce_unknown() {
+    assert_snapshot!(
+        infer_with_mismatches(r#"
+fn foo() -> u32 {
+    return unknown;
+}
+"#, true),
+        @r###"
+    [17; 40) '{     ...own; }': !
+    [23; 37) 'return unknown': !
+    [30; 37) 'unknown': u32
+    "###
+    );
+}
+
 #[test]
 fn coerce_autoderef() {
     assert_snapshot!(