[LLVMbugs] [Bug 18404] New: Bug in regex_token_iterator::operator++(int) implementation

bugzilla-daemon at llvm.org bugzilla-daemon at llvm.org
Mon Jan 6 19:18:36 PST 2014


http://llvm.org/bugs/show_bug.cgi?id=18404

            Bug ID: 18404
           Summary: Bug in regex_token_iterator::operator++(int)
                    implementation
           Product: libc++
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: All Bugs
          Assignee: hhinnant at apple.com
          Reporter: zhangmingze at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The bug is explained in

http://stackoverflow.com/questions/20323648/regex-token-iterator-it-bug/20963149#20963149



 regex_token_iterator operator++(int)
 {
        regex_token_iterator __t(*this); 
        std::cout << "test---" << *__t << "---test" << endl;
        ++(*this);
        std::cout << "test---" << *__t << "---test" << endl;
        return __t;
 }
you find that the value of *__t changed after ++(*this) !

Further digging into you will find that,

*__t is actually implemented by returning internal value_type pointer _result,
while _result actually points to &_position->prefix(), which is the address of
match_results' _prefix object, the address of this object never changed, but
the content of it changed.

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