detect and diagnose empty case ranges:

switch.c:16:8: warning: empty case range specified
  case 100 ... 99: ;  // expected-warning {{empty case range}}
       ^~~~~~~~~~



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@41328 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed