CODEWITHSUNDEEP
c++templates
Nir.L
Nir.L

Reputation: 97

Non-type templates - which types are allowed?

According to the standard, this should compile:

struct Y {};
template<const Y& y> struct Z {};


int main(){
    Y y;
    Z<y> z;  // ok: no conversion and cv-qualification conversion
}

(it's taken from - http://en.cppreference.com/w/cpp/language/template_parameters).

But, it doesn't, giving this error: error: the value of ‘y’ is not usable in a constant expression

What am I missing?

Upvotes: 1

Views: 38

Answers (1)

orlp
orlp

Reputation: 117691

You are taking a reference to a local object, which is not a constant expression. If y was a global variable, it'd work just fine.

Upvotes: 2

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