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Subject: Re: Unqualified name lookup of names used in a definition of a member of a namespace.
From: Vladimir Grigoriev (vlad.moscow_at_[hidden])
Date: 2020-05-27 19:28:57

I made a typo. I meant
 
namespace N1::N3
{i
 int x = i + j;
}
 
 
You can meet me at http://cpp.forum24.ru/ or www.stackoverflow.com or http://ru.stackoverflow.com
 
 
>Четверг, 28 мая 2020, 3:24 +03:00 от Vladimir Grigoriev via Std-Discussion <std-discussion_at_[hidden]>:
> 
>It seems I have understood the quote. The quote menas that the shown program is equivalent to the following
> 
>#include <iostream>
> 
>namespace N1
>{
>    namespace N2
>    {
>        int i = 10;
>    }
>    using namespace N2;
>    namespace N3
>    {
>        extern int x;
>    }
>    inline namespace N4
>    {
>        int j = 20;
>    }
>}
> 
>int i = 1;
>int j = 2;
>namespace N1::N3
>{i
>x = i + j;
>}
>int main()
>{
>    std::cout << "N1::N3::x = " << N1::N3::x << '\n';
>}
> 
> 
> 
> 
>You can meet me at http://cpp.forum24.ru/ or www.stackoverflow.com or http://ru.stackoverflow.com
> 
> 
>>Четверг, 28 мая 2020, 3:06 +03:00 от Vladimir Grigoriev via Std-Discussion < std-discussion_at_[hidden] >:
>> 
>>According to the C++ 20 Standard (6.5.1 Unqualified name lookup)
>> 
>>14 If a variable member of a namespace is defined outside of the scope of its namespace then any name that appears in the definition of the member (after the declarator-id) is looked up as if the definition of the member occurred in its namespace. 
>> 
>>Now let’s consider the following program
>> 
>>#include <iostream>
>> 
>>namespace N1
>>{
>>    namespace N2
>>    {
>>        int i = 10;
>>    }
>>    using namespace N2;
>>    namespace N3
>>    {
>>        extern int x;
>>    }
>>    inline namespace N4
>>    {
>>        int j = 20;
>>    }
>>}
>> 
>>int i = 1;
>>int j = 2;
>>int N1::N3::x = i + j;
>> 
>>int main()
>>{
>>    std::cout << "N1::N3::x = " << N1::N3::x << '\n';
>>}
>> 
>>The MS Visual C++ 2019 produces the following result
>> 
>>N1::N3::x = 30
>> 
>>So several questions arise. The first one is the program valid? That is are the variable declarations
>> 
>>int i = 1;
>>int j = 2;
>> 
>>are visible in the this declaration
>> 
>>int N1::N3::x = i + j;
>>?
>> 
>>That is if the definition «occurs» in the namespace (according to the quote) then the names are not visible. If I am wrong then should the value of the variable x be equal to 12?  Is it a bug of the compiler that outputs the value of x equal to 30?
>> 
>>With best regards,
>>(Vlad from Moscow)
>> 
>>You can meet me at http://cpp.forum24.ru/ or www.stackoverflow.com or http://ru.stackoverflow.com
>>--
>>Std-Discussion mailing list
>>Std-Discussion_at_[hidden]
>>https://lists.isocpp.org/mailman/listinfo.cgi/std-discussion
>> 
> 
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>Std-Discussion mailing list
>Std-Discussion_at_[hidden]
>https://lists.isocpp.org/mailman/listinfo.cgi/std-discussion
> 
 

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