auto merge of #14567 : cburgdorf/rust/patch-2, r=brson
This rewrites the example to also be more aligned with the same example given in the main tutorial.
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@ -67,7 +67,7 @@ Now we can call `compute_distance()`:
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# let on_the_stack : Point = Point{x: 3.0, y: 4.0};
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# let on_the_heap : Box<Point> = box Point{x: 7.0, y: 9.0};
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# fn compute_distance(p1: &Point, p2: &Point) -> f64 { 0.0 }
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compute_distance(&on_the_stack, &*on_the_heap);
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compute_distance(&on_the_stack, on_the_heap);
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~~~
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Here, the `&` operator takes the address of the variable
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@ -77,9 +77,10 @@ value. We also call this _borrowing_ the local variable
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`on_the_stack`, because we have created an alias: that is, another
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name for the same data.
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For the second argument, we need to extract the contents of `on_the_heap`
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by derefercing with the `*` symbol. Now that we have the data, we need
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to create a reference with the `&` symbol.
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In the case of `on_the_heap`, however, no explicit action is necessary.
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The compiler will automatically convert a box box point to a reference like &point.
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This is another form of borrowing; in this case, the contents of the owned box
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are being lent out.
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Whenever a caller lends data to a callee, there are some limitations on what
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the caller can do with the original. For example, if the contents of a
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