Re: More on errors in finalizers (was: [ANN] Lua 5.4.0 (alpha) now available)

[David Heiko Kolf <david@...>]

Andrew Gierth wrote:
> So, is there any likelihood of changes with regard to the error 
> handling issues, or do I put up my "this project will never support 
> Lua 5.4" notice now?

I have now checked how .NET handles errors during garbage collection and
noticed this discussion on Stack Overflow:
<https://stackoverflow.com/questions/2692004/c-sharp-finalizer-throwing-exception>

In summary, .NET 1.1 just ignored exceptions during GC, later .NET
versions kill the entire application regardless of any try-catch blocks.

<https://docs.microsoft.com/en-us/dotnet/api/system.object.finalize?view=netframework-4.8>:
> If Finalize or an override of Finalize throws an exception, and the 
> runtime is not hosted by an application that overrides the default 
> policy, the runtime terminates the process and no active try/finally
> blocks or finalizers are executed. This behavior ensures process 
> integrity if the finalizer cannot free or destroy resources.

I am not sure how that could be translated to Lua, I don't want Lua to
terminate the host application. But whatever the solution, it should
work well with plain Lua and not just a specialized implementation of pcall.

As a further remark, I have been taught that exceptions in finalizers
(in any programming language) should be avoided at all costs, so I hope
my applications never trigger it.

Regarding the associated lua_WarnFunction I am feeling more and more
uneasy, but that is probably a topic for its own thread.

Best regards,

David