Attachment 26045 Details for Bug 51501 – test case

test case

bug.cpp (text/plain), 1.44 KB, created by Dave Abrahams on 2011-12-10 21:06:14 UTC

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Creator: Dave Abrahams

Created: 2011-12-10 21:06:14 UTC

Size: 1.44 KB

patch

obsolete

>template <class T> T declval();
>
>struct nil_ { constexpr nil_() {} };
>constexpr nil_ nil;
>
>template <class H, class T = nil_>
>struct cons_
>{
>    constexpr cons_() {}
>    constexpr cons_(H const& x, T const& y) : head(x), tail(y) {}
>
>    H head;
>    T tail;
>};
>
>template <class H, class T>
>constexpr cons_<H,T> cons(H const& h, T const& t)
>{ return cons_<H,T>(h,t); }
>
>
>#define RETURNS_CAT_0(x, y) x ## y
>#define RETURNS_CAT(x, y) RETURNS_CAT_0(x,y)
>#define RETURNS(...) -> decltype(__VA_ARGS__) { return (__VA_ARGS__); } typedef int RETURNS_CAT(RETURNS_, __LINE__)
>
>constexpr auto list()
>    RETURNS( nil );
>
>template <class T>
>constexpr auto list(T x)
>    RETURNS( cons(x, nil) );
>
>#ifndef WORKAROUND
>template <class H, class ...T>
>constexpr auto list(H h, T ...args)
>    RETURNS(cons( h, list( args... ) ));
>#else
>
>template <class... T> struct list_;
>
>template <class H, class... T>
>struct list_<H,T...>
>{
>    using type = cons_<H,typename list_<T...>::type>;
>};
>template <> struct list_<>
>{
>    using type = nil_;
>};
>
>// Used to prove we're calculating the type correctly
>template <class T, class U> struct assert_same;
>template <class T> struct assert_same<T,T>{};
>
>template <class H, class ...T>
>constexpr auto list(H h, T ...args)
>    -> typename list_<H,T...>::type
>{
>    return assert_same<
>        decltype(cons( h, list(args...) )),
>        typename list_<H,T...>::type
>    >(),
>        cons( h, list(args...) );
>}
>#endif
>
>auto list3 = list(1, 2, 3);
>
>int main() {}

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Attachments on bug 51501: 26045