Use the most highest priority exception handler when cause is set

There was some subtle breakage caused by #18774, when we removed
`#original_exception` in favor of `#cause`. However, `#cause` is
automatically set by Ruby when raising an exception from a rescue block.
With this change, we will use whichever handler has the highest priority
(whichever call to `rescue_from` came last). In cases where the outer
has lower precidence than the cause, but the outer is what should be
handled, cause will need to be explicitly unset.

Fixes #23925

1 files changed, 6 insertions, 2 deletions

diff --git a/actionpack/lib/action_controller/metal/rescue.rb b/actionpack/lib/action_controller/metal/rescue.rb
index 81b9a7b9ed..0621a7368c 100644
--- a/actionpack/lib/action_controller/metal/rescue.rb
+++ b/actionpack/lib/action_controller/metal/rescue.rb
@@ -7,8 +7,12 @@ module ActionController #:nodoc:
     include ActiveSupport::Rescuable
 
     def rescue_with_handler(exception)
-      if exception.cause && handler_for_rescue(exception.cause)
-        exception = exception.cause
+      if exception.cause
+        handler_index = index_of_handler_for_rescue(exception) || Float::INFINITY
+        cause_handler_index = index_of_handler_for_rescue(exception.cause)
+        if cause_handler_index && cause_handler_index <= handler_index
+          exception = exception.cause
+        end
       end
       super(exception)
     end