Re: [boost] [system] Possible error in error_code.hpp

From: Beman Dawes (bdawes_at_[hidden])
Date: 2007-09-20 17:10:32

Markus Schöpflin wrote:
> Hello,
> 
> this file contains code to create an error condition, which basically looks 
> like this:
> 
> ---%<---
> struct foo
> {
>    foo() {}
>    template <class T> foo(T t) { *this = make_foo(t); }
> };
> 
> inline foo make_foo(int i) { return foo(); }
> 
> foo f(42);
> --->%---
> 
> Both my compiler (Tru64 CXX 7.1) and Comeau C++ Online think this code is 
> in error:
> 
> ---%<---
> cxx: Error: test.cxx, line 4: identifier "make_foo" is undefined
>            detected during instantiation of "foo::foo(T) [with T=int]" at 
> line 9
>    template <class T> foo(T t) { *this = make_foo(t); }
> ----------------------------------------^
> --->%---
> 
> Therefore I think this should be changed to the following:
> 
> ---%<---
> struct foo;
> template <class T> foo make_foo(T);
> 
> struct foo
> {
>    foo() {}
>    template <class T> foo(T t) { *this = make_foo(t); }
> };
> 
> template<> foo make_foo(int i) { return foo(); }
> 
> foo f(42);
> --->%---
> 
> Is this correct? If yes, could that header be fixed?

AFAICT you are correct. I've updated the header accordingly.

I deliberately did not change error_code_user_test.cpp. It may require 
"template<>" be inserted in front of make_error_* overloads, but I want 
to let the test run through Tru64 CXX 7.1 to verify that before I change 
the test code. AFAIK, the code will still work OK with the compilers it 
is currently working with.

Thanks for the report and fix!

--Beman