Rollup merge of #145277 - dingxiangfei2009:fold-coercion-into-const, r=nnethercote

Do not materialise X in [X; 0] when X is unsizing a const

Fix rust-lang/rust#143671

It turns out that MIR builder materialise `X` in `[X; 0]` into a temporary local when `X` is unsizing a `const`. This led to a confusing call to destructor of `X` when such a destructor is declared. [Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=8dfc933af89efeb89c881bc77498ba63)

This patch may miss out other cases that we should avoid materialisation in case of `[X; 0]`. Suggestions to include is most welcome!