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Diffstat (limited to '')
-rw-r--r-- | src/test/ui/const-generics/issue-97007.rs | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/src/test/ui/const-generics/issue-97007.rs b/src/test/ui/const-generics/issue-97007.rs new file mode 100644 index 000000000..7036834c4 --- /dev/null +++ b/src/test/ui/const-generics/issue-97007.rs @@ -0,0 +1,88 @@ +// check-pass + +#![feature(adt_const_params, generic_const_exprs)] +#![allow(incomplete_features)] + +mod lib { + const N_ISLANDS: usize = 4; + const N_BRIDGES: usize = 7; + const BRIDGES: [(usize, usize); 7] = [(0, 1), (0, 1), (0, 2), (0, 3), (0, 3), (1, 2), (2, 3)]; + + pub type Matrix = [[usize; N_ISLANDS]; N_ISLANDS]; + + const EMPTY_MATRIX: Matrix = [[0; N_ISLANDS]; N_ISLANDS]; + + const fn build(mut matrix: Matrix, (to, from): (usize, usize)) -> Matrix { + matrix[to][from] += 1; + matrix[from][to] += 1; + matrix + } + + pub const fn walk(mut matrix: Matrix, from: usize, to: usize) -> Matrix { + matrix[from][to] -= 1; + matrix[to][from] -= 1; + matrix + } + + const fn to_matrix(bridges: [(usize, usize); N_BRIDGES]) -> Matrix { + let matrix = EMPTY_MATRIX; + + let matrix = build(matrix, bridges[0]); + let matrix = build(matrix, bridges[1]); + let matrix = build(matrix, bridges[2]); + let matrix = build(matrix, bridges[3]); + let matrix = build(matrix, bridges[4]); + let matrix = build(matrix, bridges[5]); + let matrix = build(matrix, bridges[6]); + + matrix + } + + const BRIDGE_MATRIX: [[usize; N_ISLANDS]; N_ISLANDS] = to_matrix(BRIDGES); + + pub struct Walk<const CURRENT: usize, const REMAINING: Matrix> { + _p: (), + } + + impl Walk<0, BRIDGE_MATRIX> { + pub const fn new() -> Self { + Self { _p: () } + } + } + + impl<const CURRENT: usize, const REMAINING: Matrix> Walk<CURRENT, REMAINING> { + pub fn proceed_to<const NEXT: usize>( + self, + ) -> Walk<NEXT, { walk(REMAINING, CURRENT, NEXT) }> { + Walk { _p: () } + } + } + + pub struct Trophy { + _p: (), + } + + impl<const CURRENT: usize> Walk<CURRENT, EMPTY_MATRIX> { + pub fn collect_prize(self) -> Trophy { + Trophy { _p: () } + } + } +} + +pub use lib::{Trophy, Walk}; + +fn main() { + // Example, taking the first step + let _ = Walk::new().proceed_to::<1>(); + + // Don't be so eager to collect the trophy + // let trophy = Walk::new() + // .proceed_to::<1>() + // .proceed_to::<0>() + // .collect_prize(); + + // Can't just make a Trophy out of thin air, you must earn it + // let trophy: Trophy = Trophy { _p: () }; + + // Can you collect the Trophy? +} |