From b20f7492f10f382034247167c50d41cc8f916b84 Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <jakob.botsch.nielsen@gmail.com>
Date: Wed, 7 Jan 2026 12:57:25 +0100
Subject: [PATCH] JIT: Mark non-internal block as imported

The JIT has some debug checking that validates that non-internal blocks
are always marked `BBF_IMPORTED`. We introduce such a block in the async
rewrite (it should not be internal due to debug info), so make sure we
uphold that invariant.
---
 src/coreclr/jit/async.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/coreclr/jit/async.cpp b/src/coreclr/jit/async.cpp
index e0e75bd3e120c6..1d395a01ddfb62 100644
--- a/src/coreclr/jit/async.cpp
+++ b/src/coreclr/jit/async.cpp
@@ -2016,6 +2016,8 @@ BasicBlock* AsyncTransformation::RethrowExceptionOnResumption(BasicBlock*
     if ((rethrowExceptionBB->Prev() == block) && !block->HasFlag(BBF_INTERNAL))
     {
         rethrowExceptionBB->RemoveFlags(BBF_INTERNAL);
+        // Non-internal blocks must be marked imported
+        rethrowExceptionBB->SetFlags(BBF_IMPORTED);
     }
 
     BasicBlock* storeResultBB = m_comp->fgNewBBafter(BBJ_ALWAYS, resumeBB, true);