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Do all functions default to external linkage by default?

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I just have a hard time thinking about some functions that default to internal linkage,are there any? by default of course.

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Inline or static functions have internal linkage, non-inline and non-static functions, which I presume you mean by "default" since you don't decorate them with additional keywords, have external linkage.

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Functions (and everything else) in an anonymous namespace have internal linkage as well, since that has deprecated the use of the static qualifier in C++ now.

Edited by Paradigm Shifter

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Functions (and everything else) in an anonymous namespace have internal linkage as well, since that has deprecated the use of the static qualifier in C++ now.


Note that C++11 un-deprecated the usage of the static qualifier.

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Not that making it deprecated stopped people using it anyway ;)

 

So why did they do that? I suppose it is easier to tell from the declaration something has internal linkage if it has a static qualifier rather than having to check to see if it is inside an anonymous namespace...

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So why did they do that? I suppose it is easier to tell from the declaration something has internal linkage if it has a static qualifier rather than having to check to see if it is inside an anonymous namespace...


They just changed the wording so that it's not longer deprecated. The C++ committee likely still thinks anonymous namespaces are superior, but (from what I've read) decided it's pointless to officially deprecate it. There was no technical need for it to be deprecated.

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Functions (and everything else) in an anonymous namespace have internal linkage as well, since that has deprecated the use of the static qualifier in C++ now.

I know I've responded to you like this before so it kind of feels like I'm picking on you, but... symbols in an anonymous namespace typically have external linkage, they just happen to have a unique name automatically associated with them that is not accessible from the outside.

 

Wouldn't say it has much of an impact in every-day code, but one place where is matters is for example template parameters: reference of pointer template parameters can only be instantiated with symbols of external linkage. Therefore, you can pass the reference or pointer to a variable within an anonymous namespace, but not a static variable, as a reference or pointer template parameter.

static int bar1 = 0;
namespace { int bar2 = 0; }
 
template<int *> void foo() {}
 
int main() {
    foo<&bar1>(); // error, bar1 does not have external linkage
    foo<&bar2>(); // ok, bar2 has external linkage
}

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Not really following you guys.So,if I put a function/variable in a namespace created by me,the function/variable will have internal linkage right?

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Unless you make it static, a function or variable in a namespace typically has external linkage. And that applies to anonymous namespaces as well.

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