Re: is a typedef necessary?

Marc <>
Mon, 6 Sep 2010 08:17:10 -0700 (PDT)
On 6 sep, 16:12, Armen Tsirunyan <> wrote:

Thank you very much, Marc

If you take into account linkage (extern "C" vs extern "C++"), some
things can't be written without a typedef.

for example what?

A function that takes as first argument a C function and as second
argument a C++ function, for instance. (note that few compilers
implement this properly)

struct IncrementFunctorClassWithNoOperatorParentheses
   static int f(int n) { return n+1; }
   typedef int(*pf) (int);
   operator pf () { return &f; }


   (*operator int ())(int) { return &f; }

This still doesn't work on MSVC9.0
error C2091: function returns function
error C2586: incorrect user-defined conversion syntax : illegal

works with g++ and Intel,
produces "error: must use a typedef to declare a conversion to 'int (*)
(int)'" with clang.

Who is right? :) I mean, does the standard indirectly imply whether or
not (*operator int ())(int) { return &f; } is supposed to work?

The way I understand it, if there was a valid syntax, that would be
it, but the standard says that a conversion-function-id starts with
the keyword operator, so it can't be legal. Also, it is a gcc

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