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#include <memory>
 
class Base{};
class Derived : public Base {};
class ExtraDerived : public Derived {};
 
 
bool IsBase(Base*){ return true; }
bool IsBase(Derived*){ return false; }
 
bool IsBase(std::shared_ptr<Base>){ return true; }
bool IsBase(std::shared_ptr<Derived>){ return false; }
 
int main() 
{
    auto derived = std::make_shared<Derived>();
    auto extra_derived = std::make_shared<ExtraDerived>();
    // works
    auto raw_result_derived = IsBase(derived.get());
    auto raw_result_extra_derived = IsBase(extra_derived.get());
    auto shared_result_derived = IsBase(derived);
    // doesn't work
    auto shared_result_extra_derived = IsBase(extra_derived);
}

prog.cpp: In function ‘int main()’:
prog.cpp:23:60: error: call of overloaded ‘IsBase(std::shared_ptr<ExtraDerived>&)’ is ambiguous
prog.cpp:23:60: note: candidates are:
prog.cpp:11:6: note: bool IsBase(std::shared_ptr<Base>)
prog.cpp:12:6: note: bool IsBase(std::shared_ptr<Derived>)
prog.cpp:23:60: error: unable to deduce ‘auto’ from ‘<expression error>’
prog.cpp:19:10: warning: unused variable ‘raw_result_derived’ [-Wunused-variable]
prog.cpp:20:10: warning: unused variable ‘raw_result_extra_derived’ [-Wunused-variable]
prog.cpp:21:10: warning: unused variable ‘shared_result_derived’ [-Wunused-variable]
prog.cpp:23:10: warning: unused variable ‘shared_result_extra_derived’ [-Wunused-variable]

Standard output is empty