Re: Template conversion operator specialization

=?ISO-8859-1?Q?Daniel_Kr=FCgler?= <>
Sun, 18 May 2014 03:35:01 -0700 (PDT)
Am 18.05.2014 02:55, schrieb TS:

I have some problem regarding template conversion operator on MSVC.

class Test {
   template <typename T>
   operator T() const;
   operator int() {
       return 4;

Test::operator int() const {
   return 3;

The above code compiles fine with GCC but is rejected by MSVC:

error C2910: 'Test::operator int' : cannot be explicitly specialized

This seems odd and looks like a compiler error to me. Interestingly the following variant of your code is accepted by MSVC:

struct Test2 {
 template <class T> T f() const;
 int f() { return 4; }

template<> int Test2::f() const { return 3; }

However, I do need to keep both template and non-template version of
operator int() for a particular reason. Any ideas?

A possible workaround is to use a helper template as follows:

class Test {
  template<class T>
  T conv_func_impl() const;
  template <typename T>
  operator T() const {
      return conv_func_impl<T>();
  operator int() {
      return 4;

template<> int Test::conv_func_impl() const { return 3; }

HTH & Greetings from Bremen,

Daniel Kr?gler

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