Rollup merge of rust-lang#55694 - jsirs:issue-31076, r=oli-obk

Fixes rust-lang#31076

src/librustc_typeck/check/method/mod.rs

@@ -289,8 +289,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         // Trait must have a method named `m_name` and it should not have
         // type parameters or early-bound regions.
         let tcx = self.tcx;
-        let method_item =
-            self.associated_item(trait_def_id, m_name, Namespace::Value).unwrap();
+        let method_item = match self.associated_item(trait_def_id, m_name, Namespace::Value) {
+            Some(method_item) => method_item,
+            None => {
+                tcx.sess.delay_span_bug(span,
+                    "operator trait does not have corresponding operator method");
+                return None;
+            }
+        };
         let def_id = method_item.def_id;
         let generics = tcx.generics_of(def_id);
         assert_eq!(generics.params.len(), 0);

src/test/ui/issues/issue-31076.rs

@@ -0,0 +1,17 @@
+#![feature(no_core, lang_items)]
+#![no_core]
+
+#[lang="sized"]
+trait Sized {}
+
+#[lang="add"]
+trait Add<T> {}
+
+impl Add<i32> for i32 {}
+
+fn main() {
+    let x = 5 + 6;
+    //~^ ERROR binary operation `+` cannot be applied to type `{integer}`
+    let y = 5i32 + 6i32;
+    //~^ ERROR binary operation `+` cannot be applied to type `i32`
+}

src/test/ui/issues/issue-31076.stderr

@@ -0,0 +1,19 @@
+error[E0369]: binary operation `+` cannot be applied to type `{integer}`
+  --> $DIR/issue-31076.rs:13:13
+   |
+LL |     let x = 5 + 6;
+   |             ^^^^^
+   |
+   = note: an implementation of `std::ops::Add` might be missing for `{integer}`
+
+error[E0369]: binary operation `+` cannot be applied to type `i32`
+  --> $DIR/issue-31076.rs:15:13
+   |
+LL |     let y = 5i32 + 6i32;
+   |             ^^^^^^^^^^^
+   |
+   = note: an implementation of `std::ops::Add` might be missing for `i32`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0369`.