Split PlaceContext::Store into Store & AsmOutput
Outputs in InlineAsm can be read-write, so splitting it out is useful for things like Store-Store folding, as that's unsound for a Store-AsmOutput.
This PR is intended to make no changes, just be the mechanical split of the enum. Future changes can use the split, like a MIR pass I'm working on and perhaps two-phase borrows (see this FIXME: https://github.com/rust-lang/rust/pull/46852/files#diff-74dcd7740ab2104cd2b9a3b68dd4f208R543)
Outputs in InlineAsm can be read-write, so splitting it out is useful for things like Store-Store folding, as it cannot be done for a Store-AsmOutput.
This PR is intended to make no changes, just be the mechanical split of the enum. Future changes can use the split, like a MIR pass I'm working on and perhaps two-phase borrows.
To handle packed structs with destructors (which you'll think are a rare
case, but the `#[repr(packed)] struct Packed<T>(T);` pattern is
ever-popular, which requires handling packed structs with destructors to
avoid monomorphization-time errors), drops of subfields of packed
structs should drop a local move of the field instead of the original
one.
cc #27060 - this should deal with that issue after codegen of drop glue
is updated.
The new errors need to be changed to future-compatibility warnings, but
I'll rather do a crater run first with them as errors to assess the
impact.
check_unsafety: fix unused unsafe block duplication
The duplicate error message is later removed by error message
deduplication, but it still appears on beta and is still a bug.
r? @eddyb
