Simplify the unwind crate

[bjorn3]

Use cfg_select! and unify type definitions.

[rustbot]

r? @Mark-Simulacrum

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[bjorn3]

@xobs would you be able to check if the second commit doesn't break Xous?

[rustbot]

miri is developed in its own repository. If possible, consider making this change to rust-lang/miri instead.

cc @rust-lang/miri

[xobs]

At first blush, it doesn't compile:

Compiling panic_unwind v0.0.0 (/Users/seancross/Code/Xous/rust/library/panic_unwind)
warning: dropping unsupported crate type `dylib` for target `riscv32imac-unknown-xous-elf`

error[E0433]: cannot find `FrameInfoKind` in `unwind`
  --> std/src/sys/pal/xous/mod.rs:23:35
   |
23 |                     kind: unwind::FrameInfoKind::EhFrame(unsafe { EH_FRAME_ADDRESS }),
   |                                   ^^^^^^^^^^^^^ could not find `FrameInfoKind` in `unwind`

error[E0405]: cannot find trait `EhFrameFinder` in crate `unwind`
  --> std/src/sys/pal/xous/mod.rs:16:25
   |
16 |     unsafe impl unwind::EhFrameFinder for EhFrameFinder {
   |                         ^^^^^^^^^^^^^ not found in `unwind`

error[E0425]: cannot find type `FrameInfo` in crate `unwind`
  --> std/src/sys/pal/xous/mod.rs:17:54
   |
17 |         fn find(&self, _pc: usize) -> Option<unwind::FrameInfo> {
   |                                                      ^^^^^^^^^ not found in `unwind`

error[E0422]: cannot find struct, variant or union type `FrameInfo` in crate `unwind`
  --> std/src/sys/pal/xous/mod.rs:21:30
   |
21 |                 Some(unwind::FrameInfo {
   |                              ^^^^^^^^^ not found in `unwind`

error[E0425]: cannot find function `set_custom_eh_frame_finder` in crate `unwind`
  --> std/src/sys/pal/xous/mod.rs:48:21
   |
48 |             unwind::set_custom_eh_frame_finder(&super::eh_unwinding::EH_FRAME_SETTINGS).ok();
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^ not found in `unwind`

Some errors have detailed explanations: E0405, E0422, E0425, E0433.
For more information about an error, try `rustc --explain E0405`.

[Mark-Simulacrum]

@rustbot author

r=me on the general approach once we get xous working -- I'd expect you can check at least compilation locally with x.py check? You might need to skip bootstrap's sanity checks for a c toolchain.

[bjorn3]

./x.py check --target riscv32imac-unknown-xous-elf library now passes minus pre-existing implicit_provenance_casts lint violations.

@bors r=Mark-Simulacrum

[rust-bors]

📌 Commit 64811e9 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bjorn3]

Opened #159174 for the lint warnings.

[JonathanBrouwer]

💔 I suspect this PR failed tests as part of a rollup
@bors r-

After fixing the problem, consider running a try job for the failed job before re-approving.

Link to failure: #159187 (comment)

[rust-bors]

This pull request was unapproved.

This PR was contained in a rollup (#159187), which was unapproved.

View changes since this unapproval

[bjorn3]

I've reverted the unwinder_private_data_size and _Unwind_Exception.private visibility changes. Turns out EHABI on ARM does genuinely require the personality function to touch the private field.