rust - Who owns a value without a let binding? -

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consider following code:

struct mystruct {     not_copyable: notcopyable }  struct notcopyable;  fn main() {     let foo = mystruct { not_copyable: notcopyable };     foo.not_copyable;     foo.not_copyable;      // found out simpler "foo; foo;" create same problem }

this fails compile with

src/main.rs:17:5: 17:21 error: use of moved value: `foo.not_copyable` [e0382] src/main.rs:17     foo.not_copyable;                    ^~~~~~~~~~~~~~~~ src/main.rs:16:5: 16:21 note: `foo.not_copyable` moved here because has type `notcopyable`, non-copyable src/main.rs:16     foo.not_copyable;                    ^~~~~~~~~~~~~~~~ error: aborting due previous error

while i'm still not versed in ownership system, think why couldn't create 2 let bindings foo.not_copyable. in case there no binding. owns not_copyable here; did move?

so owns `not_copyable here; did move?

no one. expression foo.not_copyable has pull value out of structure, because value result of expression. don't do value beside point; asked value, gave value.

it's possible compiler might able optimise out under circumstances, without that, it's going move value asked to.

and yes, foo;foo; same thing: notcopyable not copyable, neither mystring.


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