added a test for definition-side checking with expected failure (#673)

executable_semantics/testdata/generic_function_fail3.carbon

@@ -0,0 +1,11 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+fn id[T:! Type](x: T) -> T {
+  return x + 0;
+}
+
+fn main() -> Int {
+  return id(0);
+}