59bb9505bc
Allow partially moved values in match
This PR attempts to unify the behaviour between `let _ = PLACE`, `let _: TY = PLACE;` and `match PLACE { _ => {} }`.
The logical conclusion is that the `match` version should not check for uninitialised places nor check that borrows are still live.
The `match PLACE {}` case is handled by keeping a `FakeRead` in the unreachable fallback case to verify that `PLACE` has a legal value.
Schematically, `match PLACE { arms }` in surface rust becomes in MIR:
```rust
PlaceMention(PLACE)
match PLACE {
// Decision tree for the explicit arms
arms,
// An extra fallback arm
_ => {
FakeRead(ForMatchedPlace, PLACE);
unreachable
}
}
```
`match *borrow { _ => {} }` continues to check that `*borrow` is live, but does not read the value.
`match *borrow {}` both checks that `*borrow` is live, and fake-reads the value.
Continuation of ~https://github.com/rust-lang/rust/pull/102256~ ~https://github.com/rust-lang/rust/pull/104844~
Fixes https://github.com/rust-lang/rust/issues/99180 https://github.com/rust-lang/rust/issues/53114
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| .. | ||
| auxiliary | ||
| abi-mismatch.rs | ||
| abi-mismatch.stderr | ||
| assoc_const_2.rs | ||
| assoc_const_2.stderr | ||
| assoc_const.rs | ||
| assoc_const.stderr | ||
| box.rs | ||
| box.stderr | ||
| const_refers_to_static_cross_crate.32bit.stderr | ||
| const_refers_to_static_cross_crate.64bit.stderr | ||
| const_refers_to_static_cross_crate.rs | ||
| const_refers_to_static.32bit.stderr | ||
| const_refers_to_static.64bit.stderr | ||
| const_refers_to_static.rs | ||
| drop.rs | ||
| drop.stderr | ||
| feature-gate-unleash_the_miri_inside_of_you.rs | ||
| feature-gate-unleash_the_miri_inside_of_you.stderr | ||
| inline_asm.rs | ||
| inline_asm.stderr | ||
| mutable_references_err.32bit.stderr | ||
| mutable_references_err.64bit.stderr | ||
| mutable_references_err.rs | ||
| mutable_references.rs | ||
| mutable_references.stderr | ||
| mutating_global.rs | ||
| mutating_global.stderr | ||
| non_const_fn.rs | ||
| non_const_fn.stderr | ||
| ptr_arith.rs | ||
| ptr_arith.stderr | ||
| raw_mutable_const.rs | ||
| raw_mutable_const.stderr | ||
| slice_eq.rs | ||
| tls.rs | ||
| tls.stderr | ||