Re: [PATCH] gdbsupport: assert upon an unhandled exception in scope_exit

[Andrew Burgess <aburgess@redhat.com>]

Stephan Rohr <stephan.rohr@intel.com> writes:

> From: Mihails Strasuns <mihails.strasuns@intel.com>
>
> Add a catch-all statement in a scope_exit_base class destructor to turn
> any unhandled exception from "POLICY::on_exit ()" into a GDB assertion -
> any such case is a programming error, because it is not legal in C++ to
> throw from a destructor.
>
> Co-Authored-By: Rohr, Stephan <stephan.rohr@intel.com>
> ---
>  gdbsupport/scope-exit.h | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/gdbsupport/scope-exit.h b/gdbsupport/scope-exit.h
> index c90b3194cb5..1dfdb1ef695 100644
> --- a/gdbsupport/scope-exit.h
> +++ b/gdbsupport/scope-exit.h
> @@ -68,7 +68,17 @@ class scope_exit_base : private POLICY
>    ~scope_exit_base ()
>    {
>      if (!m_released)
> -      POLICY::on_exit ();
> +      {
> +	try
> +	  {
> +	    POLICY::on_exit ();
> +	  }
> +	catch (const gdb_exception &ex)
> +	  {
> +	    gdb_assert_not_reached ("unhandled exception in scope exit: %s",
> +				    ex.message != nullptr ? ex.what () : "");

I was originally going to write ex.message cannot be nullptr as we never
guard calls to ex.what anywhere else in GDB.  But after checking, it is
possible to create a gdb_exception with a nullptr message.  I guess in
practice though this never happens as any exception thrown vie
error(...) will always have been give a message, you'd have to work hard
to throw an exception without a message.

I wonder if we should make the what() function handle this case?  But I
suspect that's for another day.  I think this commit is fine as is, so:

Approved-By: Andrew Burgess <aburgess@redhat.com>

Thanks,
Andrew


> +	  }
> +      }
>    }
>  
>    DISABLE_COPY_AND_ASSIGN (scope_exit_base);
> -- 
> 2.43.0
>
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