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  1. #include <map>
  2. #include <iostream>
  3. #include <utility>
  4. #include <typeinfo>
  5. #include <string>
  6. class A {};
  7. class B {};
  8. struct type_forward
  9.             {
  10.                 /// NOTE: Add more type-forwarding here
  11.                 struct type_impl
  12.                 {
  13.                     typedef int key_type;
  14.                 };
  15.                 struct A_forward: public type_impl
  16.                 {
  17.                     typedef A type;
  18.                 };
  19.                 struct B_forward: public type_impl
  20.                 {
  21.                     typedef B type;
  22.                 };
  23.                 struct string_forward: public type_impl
  24.                 {
  25.                     typedef std::string type;
  26.                 };
  27.                 static std::map<type_impl::key_type, type_impl> type_forwardings;
  28.             };
  29. std::map<type_forward::type_impl::key_type, type_forward::type_impl> type_forward::type_forwardings =
  30.     std::map<type_forward::type_impl::key_type, type_forward::type_impl>();
  31. int main()
  32. {
  33.     type_forward::type_forwardings.insert({1, type_forward::A_forward()});
  34.     type_forward::type_forwardings.insert({2, type_forward::B_forward()});
  35.     type_forward::type_forwardings.insert({3, type_forward::string_forward()});
  36.     auto X(type_forward::type_forwardings.at(1));
  37.     auto XX(type_forward::type_forwardings.at(2));
  38.     auto XXX(type_forward::type_forwardings.at(3));
  39.  
  40.     decltype(X)::type Z; /// Z doit être de type A !
  41.     decltype(XX)::type ZZ; /// ZZ doit être de type B !
  42.     decltype(XXX)::type ZZZ; /// ZZZ doit être de type std::string !
  43. }
Compilation error #stdin compilation error #stdout 0s 0KB
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stdin
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Standard input is empty
compilation info 
prog.cpp: In function ‘int main()’:
prog.cpp:40:5: error: ‘type’ is not a member of ‘type_forward::type_impl’
prog.cpp:40:23: error: expected ‘;’ before ‘Z’
prog.cpp:41:5: error: ‘type’ is not a member of ‘type_forward::type_impl’
prog.cpp:41:24: error: expected ‘;’ before ‘ZZ’
prog.cpp:42:5: error: ‘type’ is not a member of ‘type_forward::type_impl’
prog.cpp:42:25: error: expected ‘;’ before ‘ZZZ’
stdout
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Standard output is empty
https://ideone.com/VCwgt8
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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