Add & to REQUIRE_THROWS_AS type?

[joto]

Exceptions should generally be caught by reference (catch(some_type&)). But if you give a simple type to REQUIRE_THROWS_AS({...}, some_type);, the macro will generate a catch by value (catch(some_type)). Not really a problem, but clang-tidy complains. Of course I can just use references myself, but it is not clear to the user that he always has to do this. Maybe we could change the INTERNAL_CATCH_THROWS_AS macro):

-            catch( exceptionType ) { \
+            catch( std::add_lvalue_reference<exceptionType>::type ) { \

Unfortunately this solution only works in C++11.

[nabijaczleweli]

add_*_reference<> can be trivially implemented in usercode, so you could just have:

namespace catch {
#if cpluspluseleven
  template<class T>
  using add_lvalue_reference = std::add_lvalue_reference<T>;
#else
  template <typename T>
  struct add_lvalue_reference {
    typedef T & type;
  };
  template <typename T>
  struct add_lvalue_reference<T &> {
    typedef T & type;
  };
  template <typename T>
  struct add_lvalue_reference<T &&> {
    typedef T & type;
  };
#endif
}

To test:

CHECK(std::is_same<catch::add_lvalue_reference<int &&>::type, int &>::value);
CHECK(std::is_same<catch::add_lvalue_reference<int &>::type, int &>::value);
CHECK(std::is_same<catch::add_lvalue_reference<int>::type, int &>::value);