--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/llvm/test/TableGen/ConstraintChecking3.td	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,8 @@
+// RUN: not llvm-tblgen -gen-asm-writer -I %p -I %p/../../include %s 2>&1 | FileCheck %s -DFILE=%s
+
+include "ConstraintChecking.inc"
+
+// (This is illegal because the '=' has to be surrounded by whitespace)
+
+// CHECK: [[FILE]]:[[@LINE+1]]:1: error: Illegal format for tied-to constraint in 'Foo'
+def Foo : TestInstructionWithConstraints<"$dest1=$dest2">;