Change a span_bug to span_delayed_bug

to fix an ICE caused when a with expression is not a struct

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -734,7 +734,10 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
                 // struct; however, when EUV is run during typeck, it
                 // may not. This will generate an error earlier in typeck,
                 // so we can just ignore it.
-                span_bug!(with_expr.span, "with expression doesn't evaluate to a struct");
+                self.cx.tcx().dcx().span_delayed_bug(
+                    with_expr.span,
+                    "with expression doesn't evaluate to a struct",
+                );
             }
         }
 

tests/ui/typeck/ice-with-expr-not-struct-127332.rs

@@ -0,0 +1,23 @@
+// Regression test for ICE #127332
+
+// Tests that we do not ICE when a with expr
+// is not a struct but something else like an
+// enum in this case
+// This ICE occurred only when the enclosing
+// function was async
+
+
+// Using 2018 edition to supporess an irrelevant
+// error about async fn's
+//@ edition:2018
+
+async fn fun() {
+    enum Foo {
+        A { x: u32 },
+    }
+    let orig = Foo::A { x: 5 };
+    Foo::A { x: 6, ..orig };
+    //~^ ERROR functional record update syntax requires a struct
+}
+
+fn main() {}

tests/ui/typeck/ice-with-expr-not-struct-127332.stderr

@@ -0,0 +1,9 @@
+error[E0436]: functional record update syntax requires a struct
+  --> $DIR/ice-with-expr-not-struct-127332.rs:19:22
+   |
+LL |     Foo::A { x: 6, ..orig };
+   |                      ^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0436`.