121 lines
4.8 KiB
Rust
121 lines
4.8 KiB
Rust
fn main() {
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struct S; // Not `Copy`.
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let mut tup0 = (S, S);
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let mut tup1 = (S, S, S);
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let tup2 = (S, S);
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let tup3 = (S, S, S);
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let tup4 = (S, S);
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let mut arr0 = [S, S, S];
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let mut arr1 = [S, S, S, S, S];
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let arr2 = [S, S, S];
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let arr3 = [S, S, S, S, S];
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// The `mov` bindings require that we capture the scrutinees by-move.
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let mut closure = || {
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// Tuples...
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let (ref mut borrow, mov) = tup0;
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let (mov, _, ref mut borrow) = tup1;
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let (ref borrow, mov) = tup2;
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let (mov, _, ref borrow) = tup3;
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let (ref borrow, mov) = tup4;
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// Arrays...
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let [mov @ .., ref borrow] = arr0;
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let [_, ref mut borrow @ .., _, mov] = arr1;
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let [mov @ .., ref borrow] = arr2;
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let [_, ref borrow @ .., _, mov] = arr3;
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};
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// Now we try to borrow and move the captures, which should result in errors...
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// ...for tuples:
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drop(&tup0); //~ ERROR borrow of moved value: `tup0`
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drop(&tup1); //~ ERROR borrow of moved value: `tup1`
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drop(&tup2); //~ ERROR borrow of moved value: `tup2`
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drop(&tup3); //~ ERROR borrow of moved value: `tup3`
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// Ostensibly this should compile.
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// However, because closures don't capture individual fields, which is changed in RFC 2229,
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// this won't compile because the entire product is moved into the closure.
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// The same applies to the array patterns below.
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drop(&tup4.0); //~ ERROR borrow of moved value: `tup4`
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// ...for arrays:
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drop(&arr0); //~ ERROR borrow of moved value: `arr0`
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let [_, mov1, mov2, mov3, _] = &arr1; //~ ERROR borrow of moved value: `arr1`
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drop(&arr2); //~ ERROR borrow of moved value: `arr2`
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let [_, mov1, mov2, mov3, _] = &arr3; //~ ERROR borrow of moved value: `arr3`
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// Let's redo ^--- with a `match` + sum type:
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macro_rules! m {
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($p:pat = $s:expr) => {
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match $s {
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Some($p) => {}
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_ => {}
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}
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};
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}
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let mut tup0: Option<(S, S)> = None;
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let mut tup1: Option<(S, S, S)> = None;
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let tup2: Option<(S, S)> = None;
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let tup3: Option<(S, S, S)> = None;
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let tup4: Option<(S, S)> = None;
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let mut arr0: Option<[S; 3]> = None;
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let mut arr1: Option<[S; 5]> = None;
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let arr2: Option<[S; 3]> = None;
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let arr3: Option<[S; 5]> = None;
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let mut closure = || {
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m!((ref mut borrow, mov) = tup0);
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m!((mov, _, ref mut borrow) = tup1);
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m!((ref borrow, mov) = tup2);
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m!((mov, _, ref borrow) = tup3);
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m!((ref borrow, mov) = tup4);
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m!([mov @ .., ref borrow] = arr0);
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m!([_, ref mut borrow @ .., _, mov] = arr1);
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m!([mov @ .., ref borrow] = arr2);
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m!([_, ref borrow @ .., _, mov] = arr3);
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};
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drop(&tup0); //~ ERROR borrow of moved value: `tup0`
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drop(&tup1); //~ ERROR borrow of moved value: `tup1`
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drop(&tup2); //~ ERROR borrow of moved value: `tup2`
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drop(&tup3); //~ ERROR borrow of moved value: `tup3`
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m!((ref x, _) = &tup4); //~ ERROR borrow of moved value: `tup4`
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drop(&arr0); //~ ERROR borrow of moved value: `arr0`
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m!([_, mov1, mov2, mov3, _] = &arr1); //~ ERROR borrow of moved value: `arr1`
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drop(&arr2); //~ ERROR borrow of moved value: `arr2`
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m!([_, mov1, mov2, mov3, _] = &arr3); //~ ERROR borrow of moved value: `arr3`
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// Let's redo ^--- with `if let` (which may diverge from `match` in the future):
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macro_rules! m {
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($p:pat = $s:expr) => {
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if let Some($p) = $s {}
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};
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}
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let mut tup0: Option<(S, S)> = None;
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let mut tup1: Option<(S, S, S)> = None;
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let tup2: Option<(S, S)> = None;
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let tup3: Option<(S, S, S)> = None;
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let tup4: Option<(S, S)> = None;
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let mut arr0: Option<[S; 3]> = None;
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let mut arr1: Option<[S; 5]> = None;
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let arr2: Option<[S; 3]> = None;
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let arr3: Option<[S; 5]> = None;
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let mut closure = || {
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m!((ref mut borrow, mov) = tup0);
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m!((mov, _, ref mut borrow) = tup1);
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m!((ref borrow, mov) = tup2);
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m!((mov, _, ref borrow) = tup3);
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m!((ref borrow, mov) = tup4);
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m!([mov @ .., ref borrow] = arr0);
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m!([_, ref mut borrow @ .., _, mov] = arr1);
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m!([mov @ .., ref borrow] = arr2);
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m!([_, ref borrow @ .., _, mov] = arr3);
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};
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drop(&tup0); //~ ERROR borrow of moved value: `tup0`
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drop(&tup1); //~ ERROR borrow of moved value: `tup1`
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drop(&tup2); //~ ERROR borrow of moved value: `tup2`
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drop(&tup3); //~ ERROR borrow of moved value: `tup3`
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m!((ref x, _) = &tup4); //~ ERROR borrow of moved value: `tup4`
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drop(&arr0); //~ ERROR borrow of moved value: `arr0`
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m!([_, mov1, mov2, mov3, _] = &arr1); //~ ERROR borrow of moved value: `arr1`
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drop(&arr2); //~ ERROR borrow of moved value: `arr2`
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m!([_, mov1, mov2, mov3, _] = &arr3); //~ ERROR borrow of moved value: `arr3`
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}
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