From 16a0349571248c70fce0f279b350f9fd617a52ab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sat, 2 May 2020 12:50:57 -0700
Subject: [PATCH] Do not try to find binop method on RHS `TyErr`

Fix #71798.
---
 src/librustc_typeck/check/op.rs |  2 +-
 src/test/ui/issues-71798.rs     |  7 +++++++
 src/test/ui/issues-71798.stderr | 20 ++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/issues-71798.rs
 create mode 100644 src/test/ui/issues-71798.stderr

diff --git a/src/librustc_typeck/check/op.rs b/src/librustc_typeck/check/op.rs
index cac9113fd5d30..23004cf364725 100644
--- a/src/librustc_typeck/check/op.rs
+++ b/src/librustc_typeck/check/op.rs
@@ -251,7 +251,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             Err(()) => {
                 // error types are considered "builtin"
-                if !lhs_ty.references_error() {
+                if !lhs_ty.references_error() && !rhs_ty.references_error() {
                     let source_map = self.tcx.sess.source_map();
                     match is_assign {
                         IsAssign::Yes => {
diff --git a/src/test/ui/issues-71798.rs b/src/test/ui/issues-71798.rs
new file mode 100644
index 0000000000000..08b10463d3927
--- /dev/null
+++ b/src/test/ui/issues-71798.rs
@@ -0,0 +1,7 @@
+fn test_ref(x: &u32) -> impl std::future::Future<Output = u32> + '_ {
+    *x //~^ ERROR the trait bound `u32: std::future::Future` is not satisfied
+}
+
+fn main() {
+    let _ = test_ref & u; //~ ERROR cannot find value `u` in this scope
+}
diff --git a/src/test/ui/issues-71798.stderr b/src/test/ui/issues-71798.stderr
new file mode 100644
index 0000000000000..85da87914e768
--- /dev/null
+++ b/src/test/ui/issues-71798.stderr
@@ -0,0 +1,20 @@
+error[E0425]: cannot find value `u` in this scope
+  --> $DIR/issues-71798.rs:6:24
+   |
+LL |     let _ = test_ref & u;
+   |                        ^ not found in this scope
+
+error[E0277]: the trait bound `u32: std::future::Future` is not satisfied
+  --> $DIR/issues-71798.rs:1:25
+   |
+LL | fn test_ref(x: &u32) -> impl std::future::Future<Output = u32> + '_ {
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `u32`
+LL |     *x
+   |     -- this returned value is of type `u32`
+   |
+   = note: the return type of a function must have a statically known size
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0277, E0425.
+For more information about an error, try `rustc --explain E0277`.