the mir-validation ICE test behaves strangely on Windows hosts

let's just disable it there, this code is not platform-dependent anyway

Author: RalfJung

src/tools/miri/src/diagnostics.rs

@@ -291,7 +291,7 @@ pub fn report_error<'tcx, 'mir>(
                     ValidationErrorKind::PointerAsInt { .. } | ValidationErrorKind::PartialPointer
                 ) =>
             {
-                ecx.handle_ice(); // print interpreter backtrace
+                ecx.handle_ice(); // print interpreter backtrace (this is outside the eval `catch_unwind`)
                 bug!(
                     "This validation error should be impossible in Miri: {}",
                     format_interp_error(ecx.tcx.dcx(), e)
@@ -308,7 +308,7 @@ pub fn report_error<'tcx, 'mir>(
                 InvalidProgramInfo::AlreadyReported(_) | InvalidProgramInfo::Layout(..),
             ) => "post-monomorphization error",
             _ => {
-                ecx.handle_ice(); // print interpreter backtrace
+                ecx.handle_ice(); // print interpreter backtrace (this is outside the eval `catch_unwind`)
                 bug!(
                     "This error should be impossible in Miri: {}",
                     format_interp_error(ecx.tcx.dcx(), e)

src/tools/miri/tests/panic/mir-validation.rs

@@ -1,10 +1,13 @@
 //! Ensure that the MIR validator runs on Miri's input.
 //@rustc-env:RUSTC_ICE=0
-//@normalize-stderr-test: "\n +[0-9]+:[^\n]+" -> ""
-//@normalize-stderr-test: "\n +at [^\n]+" -> ""
-//@normalize-stderr-test: "\n +\[\.\.\. omitted [0-9]+ frames? \.\.\.\]" -> ""
+//@normalize-stderr-test: "\n +[0-9]+:.+" -> ""
+//@normalize-stderr-test: "\n +at .+" -> ""
+//@normalize-stderr-test: "\n +\[\.\.\. omitted [0-9]+ frames? \.\.\.\].*" -> ""
 //@normalize-stderr-test: "\n[ =]*note:.*" -> ""
 //@normalize-stderr-test: "DefId\([^()]*\)" -> "DefId"
+// Somehow on rustc Windows CI, the "Miri caused an ICE" message is not shown
+// and we don't even get a regular panic; rustc aborts with a different exit code instead.
+//@ignore-host-windows
 #![feature(custom_mir, core_intrinsics)]
 use core::intrinsics::mir::*;