CODEWITHSUNDEEP
c++c++11ellipsis
Johannes Schaub - litb
Johannes Schaub - litb

Reputation: 507215

My compiler allows "T&...". Is this an extension?

I was surprised when the following worked

template<typename T>
void f(T &...);

I thought that I have to declare "T" as "typename ...T" then, and that it only works in C++0x. But the above compiled in strict C++03 mode. What's going on?

Upvotes: 12

Views: 246

Answers (2)

Xeo
Xeo

Reputation: 131837

Did you call the function? Template functions don't get compiled until you call them. And in Visual Studio 2010, IntelliSense shows the real syntax of that function would be 

template <class T> void f(T&, ...)

Smells like old variable argument syntax.

Upvotes: 3

JohannesD
JohannesD

Reputation: 14461

It's just the bad old C varargs syntax; the grammar allows omitting the comma. The following are equivalent:

int printf(const char* fmt, ...);
int printf(const char* fmt...);

Upvotes: 20

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