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  1. #include <string>
  2.  
  3.     template <class T, class U>
  4.     struct sametype {};
  5.  
  6.     template <class T>
  7.     struct sametype<T,T> {typedef int same;};
  8.  
  9.     int main() {
  10.     int &refint();
  11.     std::string str();
  12.     std::string const conststr();
  13.  
  14.     auto i1 = 1; // deduce(1) gives T=int so int i1
  15.     auto i2 = i1; // deduce(i1) gives T=int so int i2
  16.     auto i3 = refint(); // deduce(refint()) gives T=int so int i3
  17.     const auto ci1 = i1; // deduce(i1) gives T=int so const int ci1
  18.     auto i4 = ci1; // deduce(ci1) gives T=int so int i4
  19.  
  20.     auto s1 = std::string(); // std::string s1
  21.     auto s2 = str(); // std::string s2
  22.     auto s3 = conststr(); // std::string s3
  23.  
  24.     extern decltype(refint()) ir1; // int &i
  25.  
  26.     sametype<decltype (i1), int>::same check_i1;
  27.     sametype<decltype (i2), int>::same check_i2;
  28.     sametype<decltype (i3), int>::same check_i3;
  29.     sametype<decltype (i4), int>::same check_i4;
  30.  
  31.     sametype<decltype (ci1), const int>::same check_ci1;
  32.  
  33.     sametype<decltype (ir1), int&>::same check_ir1;
  34.  
  35.     sametype<decltype (s1), std::string>::same check_s1;
  36.     sametype<decltype (s2), std::string>::same check_s2;
  37.     sametype<decltype (s3), std::string>::same check_s3;
  38. }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
/home/lF3hoG/ccwdfdqY.o: In function `main':
prog.cpp:(.text.startup+0x13): undefined reference to `refint()'
prog.cpp:(.text.startup+0x1f): undefined reference to `str()'
prog.cpp:(.text.startup+0x28): undefined reference to `conststr()'
collect2: error: ld returned 1 exit status
stdout
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Standard output is empty
https://ideone.com/gRZnbN
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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