miri no longer builds after rust-lang/rust#86155

[rust-highfive]

Hello, this is your friendly neighborhood mergebot.
After merging PR #86155, I observed that the tool miri has failing tests.
A follow-up PR to the repository https://github.com/rust-lang/miri is needed to fix the fallout.

cc @alexcrichton, do you think you would have time to do the follow-up work?
If so, that would be great!

[alexcrichton]

I think this is what's necessary to fix the issue, but I'll test more tomorrow when a nightly with #86155 is released

diff --git a/tests/run-pass/function_calls/exported_symbol_good_unwind.rs b/tests/run-pass/function_calls/exported_symbol_good_unwind.rs
index 3dd3b8f2..71b799a1 100644
--- a/tests/run-pass/function_calls/exported_symbol_good_unwind.rs
+++ b/tests/run-pass/function_calls/exported_symbol_good_unwind.rs
@@ -2,16 +2,10 @@
 // found in this form" errors works without `-C prefer-dynamic` (`panic!` calls foreign function
 // `__rust_start_panic`).
 // no-prefer-dynamic
-#![feature(c_unwind, unboxed_closures, unwind_attributes)]
+#![feature(c_unwind, unboxed_closures)]
 
 use std::panic;
 
-#[no_mangle]
-#[unwind(allowed)]
-extern "C" fn good_unwind_allowed() {
-    panic!();
-}
-
 #[no_mangle]
 extern "C-unwind" fn good_unwind_c() {
     panic!();
@@ -29,11 +23,6 @@ extern "rust-call" fn good_unwind_rust_call(_: ()) -> ! {
 }
 
 fn main() -> ! {
-    extern "C" {
-        #[unwind(allowed)]
-        fn good_unwind_allowed();
-    }
-    panic::catch_unwind(|| unsafe { good_unwind_allowed() }).unwrap_err();
     extern "C-unwind" {
         fn good_unwind_c();
     }
diff --git a/tests/run-pass/function_calls/exported_symbol_unwind_allowed.rs b/tests/run-pass/function_calls/exported_symbol_unwind_allowed.rs
index 0e4ec573..fd5ec494 100644
--- a/tests/run-pass/function_calls/exported_symbol_unwind_allowed.rs
+++ b/tests/run-pass/function_calls/exported_symbol_unwind_allowed.rs
@@ -1,5 +1,4 @@
-// compile-flags: -Zmiri-disable-abi-check
-#![feature(unwind_attributes, c_unwind)]
+#![feature(c_unwind)]
 
 #[no_mangle]
 extern "C-unwind" fn unwind() {
@@ -7,8 +6,7 @@ extern "C-unwind" fn unwind() {
 }
 
 fn main() {
-    extern "C" {
-        #[unwind(allowed)]
+    extern "C-unwind" {
         fn unwind();
     }
     unsafe { unwind() }

[ghost]

There are more failures in compile-fail tests (which are not run when run-pass tests fail):

failures:
    [compile-fail] compile-fail/abort-terminator.rs
    [compile-fail] compile-fail/function_calls/exported_symbol_bad_unwind2.rs
    [compile-fail] compile-fail/function_calls/exported_symbol_bad_unwind3.rs
    [compile-fail] compile-fail/panic/bad_miri_start_panic.rs
    [compile-fail] compile-fail/panic/panic_abort1.rs
    [compile-fail] compile-fail/panic/panic_abort2.rs
    [compile-fail] compile-fail/panic/panic_abort3.rs
    [compile-fail] compile-fail/panic/panic_abort4.rs

• compile-fail/abort-terminator.rs and tests/compile-fail/function_calls/exported_symbol_bad_unwind3.rs fail with error[E0557]: feature has been removed.
• Revision definition of tests/compile-fail/function_calls/exported_symbol_bad_unwind2.rs fails with abnormal termination: the program aborted execution -- unwinding past a #[rustc_allocator_nounwind] function seems to abort instead of triggering UB now.
• tests/compile-fail/panic/bad_miri_start_panic.rs does not trigger the unwinding past a stack frame that does not allow unwinding error anymore. Adding #![feature(c_unwind)] fixes it.
• All compile-fail/panic/panic_abort*.rs tests fail with this error:

  error: Undefined Behavior: calling a function with ABI C using caller ABI C-unwind
     --> /home/hyd-dev/.rustup/toolchains/miri/lib/rustlib/src/rust/library/std/src/panicking.rs:672:9
      |
  672 |         __rust_start_panic(obj)
      |         ^^^^^^^^^^^^^^^^^^^^^^^ calling a function with ABI C using caller ABI C-unwind
      |
      = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
      = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
  

  Which seems to be an ABI mismatch between panic_abort and std:
  

  rust/library/panic_abort/src/lib.rs

  Line 33 in d4ad1cf

  pub unsafe extern "C" fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 {

  
  

  rust/library/std/src/panicking.rs

  Lines 49 to 54 in d4ad1cf

  	extern "C-unwind" {
  	/// `payload` is passed through another layer of raw pointers as `&mut dyn Trait` is not
  	/// FFI-safe. `BoxMeUp` lazily performs allocation only when needed (this avoids allocations
  	/// when using the "abort" panic runtime).
  	fn __rust_start_panic(payload: *mut &mut dyn BoxMeUp) -> u32;
  	}

  
  Opened Use C-unwind ABI for __rust_start_panic in panic_abort #87787 to fix that.

[alexcrichton]

Ah ok in that case I think I unfortunately don't think I have time to personally look more into this.

[RalfJung]

The fix is ready at rust-lang/miri#1868, but bors is broken so we can't land it.