Thorsten Ottosen wrote:
Eric Niebler wrote:
Thorsten Ottosen wrote:
Eric Niebler wrote:
If make_iterator_range() returned a const-qualified iterator_range<>, this would work. Thorsten? Isn't the problem thet out is a reference?
out is a reference, which means that non-const rvalues will not bind to it. But const rvalues will because out_t will be deduced to be "iterator_range<> const". Try it and see.
I see. I certainly didn't know that. I could get it to work on gcc, but not vc8.
On what compilers does it actually work?
All of them, as far as I know. I just tried on VC8 and it worked: template<typename T> void foo(T &) {} struct empty {}; empty const bar() { empty e; return e; } int main() { foo(bar()); return 0; } Without thinking about this deeply, it seems that lightweight proxy objects such as iterator_range<> should always be returned as a const-qualified rvalues for precisely this reason. (Note that cv-qualifications on intrinsic return types are ignored, so "int foo()" and "int const foo()" are the same. Perhaps that's the problem you were seeing?) -- Eric Niebler Boost Consulting www.boost-consulting.com