Crash was possible if match() method was called on object that was moved or object created with empty constructor. Testcases updated. DIfferential revision: https://reviews.llvm.org/D24123 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280473 91177308-0d34-0410-b5e6-96231b3b80d8