Unskip NestedCatch_DuplicateLocal_Level2 #132016

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1. jjonescz

   assigned

   333fred

   on Aug 7, 2026
2. jjonescz

   added the

   Bug

   issue type on Aug 7, 2026
3. 333fred commented on Aug 7, 2026

   

   333fred

   on Aug 7, 2026

   Member

   More actions

   his appears to be a runtime-async bug in .NET 11 Preview 6. I reduced the test to the following file-based app:

   #:property Features=runtime-async=on
   #:property LangVersion=preview
   #:property Optimize=true
   #:property NoWarn=SYSLIB5007;CA2252
   
   using System;
   using System.Threading.Tasks;
   
   Test.Run();
   
   class Test
   {
       public static void Run()
       {
           new Test().M().GetAwaiter().GetResult();
       }
   
       static bool Filter(Exception ex, bool result)
       {
           Console.WriteLine(ex.Message);
           return result;
       }
   
       async Task M()
       {
           try
           {
               throw new Exception("outer");
           }
           catch (Exception ex) when (Filter(ex, false))
           {
               await Print(ex);
           }
           catch (Exception ex) when (Filter(ex, true))
           {
               try
               {
                   throw new Exception("inner");
               }
               catch (Exception ex2) when (Filter(ex2, false))
               {
                   await Print(ex);
                   await Print(ex2);
               }
               catch (Exception ex2) when (Filter(ex2, true))
               {
                   try
                   {
                       throw new Exception();
                   }
                   catch
                   {
                       await Print(ex);
                       await Print(ex2);
                   }
               }
           }
       }
   
       static async Task Print(Exception ex)
       {
           await Task.Yield();
           Console.WriteLine(ex.Message);
       }
   }

   With global.json pinned to SDK 10.0.301, this exits successfully:

   $ DOTNET_RuntimeAsync=1 dotnet run 84791.cs
   outer
   outer
   inner
   inner
   outer
   inner

   With global.json pinned to SDK 11.0.100-preview.6.26359.118, the same command fails because the second captured exception becomes null:

   $ dotnet run 84791.cs
   outer
   outer
   inner
   inner
   outer
   Unhandled exception. System.NullReferenceException: Object reference not set to an instance of an object.
      at Test.Print(Exception ex) in 84791.cs:line 63
      at Test.M() in 84791.cs:line 54

   This comment was generated by AI.
4. 333fred

   transferred this issue fromdotnet/roslynon Aug 7, 2026
5. github-actions

   added

   area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMICLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI

   on Aug 7, 2026
6. dotnet-policy-service

   added

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Aug 7, 2026
7. dotnet-policy-service commented on Aug 7, 2026

   

   dotnet-policy-servicebot

   on Aug 7, 2026 – with Dotnet Policy Service

   Contributor

   More actions

   Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
   See info in area-owners.md if you want to be subscribed.
8. jakobbotsch

   added this to the 11.0.0 milestone on Aug 7, 2026
9. jakobbotsch

   removed

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Aug 7, 2026
10. jakobbotsch

    assigned

    jakobbotsch

    and unassigned

    333fred

    on Aug 7, 2026
11. jakobbotsch

    closed this as completedin #132027on Aug 10, 2026
12. github-actions

    locked and limited conversation to collaborators on Sep 10, 2026