Rollup merge of #133211 - Strophox:miri-correct-state-update-ffi, r=RalfJung

Extend Miri to correctly pass mutable pointers through FFI

Based off of https://github.com/rust-lang/rust/pull/129684, this PR further extends Miri to execute native calls that make use of pointers to *mutable* memory.
We adapt Miri's bookkeeping of internal state upon any FFI call that gives external code permission to mutate memory.

Native code may now possibly write and therefore initialize and change the pointer provenance of bytes it has access to: Such memory is assumed to be *initialized* afterwards and bytes are given *arbitrary (wildcard) provenance*. This enables programs that correctly use mutating FFI calls to run Miri without errors, at the cost of possibly missing Undefined Behaviour caused by incorrect usage of mutating FFI.

> <details>
>
> <summary> Simple example </summary>
>
> ```rust
> extern "C" {
>   fn init_int(ptr: *mut i32);
> }
>
> fn main() {
>   let mut x = std::mem::MaybeUninit::<i32>::uninit();
>   let x = unsafe {
>     init_int(x.as_mut_ptr());
>     x.assume_init()
>   };
>
>   println!("C initialized my memory to: {x}");
> }
> ```
> ```c
> void init_int(int *ptr) {
>   *ptr = 42;
> }
> ```
> should now show `C initialized my memory to: 42`.
>
> </details>

r? ``@RalfJung``

compiler/rustc_const_eval/src/const_eval/dummy_machine.rs

@@ -168,9 +168,9 @@ impl<'tcx> interpret::Machine<'tcx> for DummyMachine {
         })
     }
 
-    fn expose_ptr(
-        _ecx: &mut InterpCx<'tcx, Self>,
-        _ptr: interpret::Pointer<Self::Provenance>,
+    fn expose_provenance(
+        _ecx: &InterpCx<'tcx, Self>,
+        _provenance: Self::Provenance,
     ) -> interpret::InterpResult<'tcx> {
         unimplemented!()
     }

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -21,9 +21,8 @@ use crate::errors::{LongRunning, LongRunningWarn};
 use crate::fluent_generated as fluent;
 use crate::interpret::{
     self, AllocId, AllocRange, ConstAllocation, CtfeProvenance, FnArg, Frame, GlobalAlloc, ImmTy,
-    InterpCx, InterpResult, MPlaceTy, OpTy, Pointer, RangeSet, Scalar, compile_time_machine,
-    interp_ok, throw_exhaust, throw_inval, throw_ub, throw_ub_custom, throw_unsup,
-    throw_unsup_format,
+    InterpCx, InterpResult, MPlaceTy, OpTy, RangeSet, Scalar, compile_time_machine, interp_ok,
+    throw_exhaust, throw_inval, throw_ub, throw_ub_custom, throw_unsup, throw_unsup_format,
 };
 
 /// When hitting this many interpreted terminators we emit a deny by default lint
@@ -586,7 +585,10 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
     }
 
     #[inline(always)]
-    fn expose_ptr(_ecx: &mut InterpCx<'tcx, Self>, _ptr: Pointer) -> InterpResult<'tcx> {
+    fn expose_provenance(
+        _ecx: &InterpCx<'tcx, Self>,
+        _provenance: Self::Provenance,
+    ) -> InterpResult<'tcx> {
         // This is only reachable with -Zunleash-the-miri-inside-of-you.
         throw_unsup_format!("exposing pointers is not possible at compile-time")
     }