Redeclaration of name of class type

Question

Consider the following example:

void foo()
{
    class A;
    class A;
}

int main()
{
    foo();
    return 0;
}

And it is work fine. Why such redecration of class type is permitted? I'm confused...

UPD: Please give me a quote from c++ spec where such redeclaration is permitted... if it possible.

Blaz Bratanic · Answer 1 · 2014-05-05T07:41:23.923

1

§ 3.1 A declaration (Clause 7) may introduce one or more names into a translation unit or redeclare names introduced by previous declarations.

Thats in the first clause.

The second clause specifies whats a declaration. I didnt copy it here because it includes quite a few examples.

edited May 05 '14 at 07:41

answered May 05 '14 at 07:39

Blaz Bratanic

2,279
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Thanks! That is exactly what I want to know. – May 05 '14 at 07:45

score 1 · Answer 2 · edited May 23 '17 at 11:57

1

Declaration and Definition are two different concepts. You can declare a name any number of times you want in a translation unit. But the definition should appear only once. check this and this

edited May 23 '17 at 11:57

Community

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answered May 05 '14 at 07:43

Rakib

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score 1 · Answer 3 · answered May 05 '14 at 07:56

1

Moreover, if each class A is declared in different cpp files as global variables the linker will raise a warn if you invoke g++ with "-warn-common"

answered May 05 '14 at 07:56

spdilo

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Redeclaration of name of class type

3 Answers3