Rollup merge of #101985 - RalfJung:generate_stacktrace, r=oli-obk

interpret: expose generate_stacktrace without full InterpCx

In Miri we sometimes want to emit diagnostics without having a full `&InterpCx` available. To avoid duplicating code, this adds a way to get a stacktrace from an arbitrary slice of interpreter frames, that Miri can use with access to just a thread manager.

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -929,11 +929,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     }
 
     #[must_use]
-    pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> {
+    pub fn generate_stacktrace_from_stack(
+        stack: &[Frame<'mir, 'tcx, M::Provenance, M::FrameExtra>],
+    ) -> Vec<FrameInfo<'tcx>> {
         let mut frames = Vec::new();
         // This deliberately does *not* honor `requires_caller_location` since it is used for much
         // more than just panics.
-        for frame in self.stack().iter().rev() {
+        for frame in stack.iter().rev() {
             let lint_root = frame.current_source_info().and_then(|source_info| {
                 match &frame.body.source_scopes[source_info.scope].local_data {
                     mir::ClearCrossCrate::Set(data) => Some(data.lint_root),
@@ -947,6 +949,11 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         trace!("generate stacktrace: {:#?}", frames);
         frames
     }
+
+    #[must_use]
+    pub fn generate_stacktrace(&self) -> Vec<FrameInfo<'tcx>> {
+        Self::generate_stacktrace_from_stack(self.stack())
+    }
 }
 
 #[doc(hidden)]