llvm dev - Oct 2015 - LLVM（3.7.0）pass has a core dump

I wrote a very simple pass. The code as follows(rude.cpp):
#include "llvm/Pass.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/IR/BasicBlock"

using namespace llvm;

namespace {
  struct rude : public FunctionPass {
    static char ID;
    rude() : FunctionPass(ID) {}

    bool runOnFunction(Function &F) override {
      errs() << "Hello,I'm rude: ";
      errs().write_escaped(F.getName()) << '\n';

      for(Function::iterator b=F.begin(),be=F.end();b!=be;++b)
      {
          errs()<<"\n\tBB:";
           for(BasicBlock::iterator i=b->begin(),ie=b->end();i!=ie;++i)
           {
               errs()<<"\n\tanalysis instructions";
            }
       }
      return false;
    }
  };
}

char Hello::ID = 9;
static RegisterPass<rude> X("rude", "rude Pass",
false, false);

then I use command :
opt -load XX/Debug+Assertion/rude.so <test1.bc> /dev/null to run the
rude.so file .
the error as follows:

​#0 0x222Bd05 llvm::sys::PrintStackTrace(llvm::raw_ostream&)
 XX/LLVM3.7.0/llvm/lib/Support/Unix/Signals.inc/:437:0
#1 0x222901a PrintStackTraceSignalHandler(void*)
 XX/LLVM3.7.0/llvm/lib/Support/Unix/Signal.inc:495:0
....

I really don't know why it is. can anyone help me?
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