Attachment 1451986 Details for Bug 1591823 – c++ file to reproduce the problem

c++ file to reproduce the problem

a.cpp (text/x-csrc), 1.55 KB, created by Hubert Krause on 2018-06-15 16:12:40 UTC

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Creator: Hubert Krause

Created: 2018-06-15 16:12:40 UTC

Size: 1.55 KB

patch

obsolete

>#include <iostream>
>#include <string>
>
>int main()
>{
>  const std::string s0{"hello world"};
>  std::string s1 {s0};
>  std::string s2 {s0};
>  std::cout << "BEFORE" << std::endl;
>  std::cout << "s0 = " << s0 << std::endl;
>  std::cout << "s1 = " << s1 << std::endl;
>  std::cout << "s2 = " << s2 << std::endl;
>
>#if 0
>  char* pszDataS1 = &s1[0];  //this old trick works as expected!
>#else  
>  char* pszDataS1 = s1.data(); //this new data() member function leads to very serious and undesired side effects!
>#endif  
>  *pszDataS1 = ' '; //should modify s1 and only s1, should *never* modify both s2 and the const(!) s0.
>
>  std::cout << "AFTER modifying s1" << std::endl;
>  std::cout << "s0 = " << s0 << "   expecting = hello world" << std::endl;
>  std::cout << "s1 = " << s1 << "   expecting =  ello world" << std::endl;
>  std::cout << "s2 = " << s2 << "   expecting = hello world" << std::endl;
>
>  return 0;
>}
>
>//th@vcrhel7-dev-thaase:[~/sandbox]: gcc --version
>//gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
>//Copyright (C) 2017 Free Software Foundation, Inc.
>//This is free software; see the source for copying conditions.  There is NO
>//warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>//
>//th@vcrhel7-dev-thaase:[~/sandbox]: g++ -std=c++17 a.cpp
>//th@vcrhel7-dev-thaase:[~/sandbox]: ./a.out
>//
>//leads to the following console output, showing very serious and undesired side effects on s2 and (const!) s0.
>//s0 = hello world!
>//s1 = hello world!
>//s2 = hello world!
>//s0 =  ello world!
>//s1 =  ello world!
>//s2 =  ello world!

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Attachments on bug 1591823: 1451986