https://issues.dlang.org/show_bug.cgi?id=17661
Martin Nowak <c...@dawg.eu> changed:
What |Removed |Added
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CC| |c...@dawg.eu
--- Comment #5 from Martin Nowak <c...@dawg.eu> ---
Well in, (R r) return => r.front, the return applies to the delegate context,
but you're escaping a reference to the argument.
What you want to check is `(return ref R r) => r.front`.
Also rewriting your front methods to a free functions helps understanding.
C front(return ref S _this) { return C(&_this); }
Obviously allowing
(R r) => front(r)
would return a dangling reference to the value parameter.
NB, if your front methods leaked a field of the range (e.g. a pointer), you'd
need a `return scope` front methods, but the `(R r) => r.front` check is fine,
since the parameter `r` isn't scoped, i.e. it might leak any pointer fields.
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