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a0d98ff0e5
Mark `simplify_aggregate_to_copy` mir-opt as unsound Mark the `simplify_aggregate_to_copy` mir-opt added in #128299 as unsound as it seems to miscompile the MCVE reported in https://github.com/rust-lang/rust/issues/132353. The mir-opt can be re-enabled once this case is fixed. ```rs fn pop_min(mut score2head: Vec<Option<usize>>) -> Option<usize> { loop { if let Some(col) = score2head[0] { score2head[0] = None; return Some(col); } } } fn main() { let min = pop_min(vec![Some(1)]); println!("min: {:?}", min); // panic happens here on beta in release mode // but not in debug mode min.unwrap(); } ``` This MCVE is included as a `run-pass` ui regression test in the first commit. I built the ui test with a nightly manually, and can reproduce the behavioral difference with `-C opt-level=0` and `-C opt-level=1`. Locally, this ui test will fail unless it was run on a compiler built with the second commit marking the mir-opt as unsound thus disabling it by default. This PR **partially reverts** commit e7386b3, reversing changes made to 02b1be1. The mir-opt implementation is just marked as unsound but **not** reverted to make reland reviews easier. Test changes are **reverted if they were not pure additions**. Tests added by the original PR received `-Z unsound-mir-opts` compile-flags. cc `@DianQK` `@cjgillot` (PR author and reviewer of #128299)