Implement binary operator overloading type inference

1 files changed, 11 insertions, 4 deletions

diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 0a141b9cb..8cc0d56d3 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -531,13 +531,20 @@ impl<'a> InferenceContext<'a> {
                         _ => Expectation::none(),
                     };
                     let lhs_ty = self.infer_expr(*lhs, &lhs_expectation);
-                    // FIXME: find implementation of trait corresponding to operation
-                    // symbol and resolve associated `Output` type
                     let rhs_expectation = op::binary_op_rhs_expectation(*op, lhs_ty.clone());
                     let rhs_ty = self.infer_expr(*rhs, &Expectation::has_type(rhs_expectation));
 
-                    // FIXME: similar as above, return ty is often associated trait type
-                    op::binary_op_return_ty(*op, lhs_ty, rhs_ty)
+                    let ret = op::binary_op_return_ty(*op, lhs_ty.clone(), rhs_ty.clone());
+
+                    if ret == Ty::Unknown {
+                        self.resolve_associated_type_with_params(
+                            lhs_ty,
+                            self.resolve_binary_op_output(op),
+                            &[rhs_ty],
+                        )
+                    } else {
+                        ret
+                    }
                 }
                 _ => Ty::Unknown,
             },