Re: [Doxygen-users] warning at explicit instantiation of overloaded template class member function

[Heese, H. <har...@ph...>]

Hi Dimitri!

Thanks for the quick answer.

You are right, the provided code does not compile. The modified example now is

//! a test class with overloaded template members
class Bar
{
public:
  //! first overload of template member function
  template <typename T>
  T foo(T a, int b)
  { return a; }

  //! second overload of template member function
  template <typename T>
  T foo(T a, double c)
  { return a; }
};

//! force instantiation of first overload for type 'short'
template short Bar::foo<short>(short, int);

If you compile this using
gcc -c bar.cpp

the corresponding object file will contain exactly one symbol (which you can see using nm). This is exactly what is intended (to force the creation of a symbol for a specific template parameter).

The syntax you suggested refers to a different concept, namely "template specialization". In that case, the statement
  template<> short Bar::foo<short>(short, int);
is a function declaration, which would require a separate function definition in order to create a corresponding symbol. If I would compile the modified example with your suggestion, then the corresponding object file does not contain any symbols (which is not what is intended).

Best regards,
Harald


-----Original Message-----
From: Dimitri van Heesch [mailto:do...@gm...]
Sent: Wednesday, August 26, 2015 4:04 PM
To: Heese, Harald
Cc: dox...@li...
Subject: Re: [Doxygen-users] warning at explicit instantiation of overloaded template class member function

Hi Harald,

> On 26 Aug 2015, at 15:19 , Heese, Harald <har...@ph...> wrote:
>
> Hi doxygen,
>
> I am encountering warnings using Doxygen 1.8.10 for the below example of overloaded template member functions with explicit instantiation of one (or more) of the overloads for specific template types.
>
> //! a test class with overloaded template members class Bar {
> public:
>  //! first overload of template member function  template <typename T>
> T foo(T a, int b);
>
>  //! second overload of template member function  template <typename
> T>  T foo(T a, double c); };
>
> //! force instantiation of first overload for type 'short'
> template short Bar::foo<short>(short, int);
>
> Output
>
> warning: no matching class member found for  template short Bar::foo<
> short >(short, int) Possible candidates:
>  'template < T >
>  T Bar::foo(T a, int b)
>  'template < T >
>  T Bar::foo(T a, double c)
>
> Is there a way to incorporate the existence of an explicit instantiation (or its accompanying doxygen documentation) in the detailed documentation of the class member (which happens if there are no overloads)?

If you use

//! force instantiation of first overload for type 'short'
template<> short Bar::foo<short>(short, int);

it should work. Note the <> after template. My compiler doesn't even compile the code without it.

Groeten,
  Dimitri


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