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25 lines
842 B
Rust
25 lines
842 B
Rust
//! Tests how we behave when the user attempts to mutate an immutable
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//! binding that was introduced by either `ref` or `ref mut`
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//! patterns.
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//!
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//! Such bindings cannot be made mutable via the mere addition of the
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//! `mut` keyword, and thus we want to check that the compiler does not
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//! suggest doing so.
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fn main() {
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let (mut one_two, mut three_four) = ((1, 2), (3, 4));
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// Bind via pattern:
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// - `a` as immutable reference (`ref`)
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// - `b` as mutable reference (`ref mut`)
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let &mut (ref a, ref mut b) = &mut one_two;
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// Attempt to reassign immutable `ref`-bound variable
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a = &three_four.0;
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//~^ ERROR cannot assign twice to immutable variable `a`
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// Attempt to reassign mutable `ref mut`-bound variable
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b = &mut three_four.1;
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//~^ ERROR cannot assign twice to immutable variable `b`
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}
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