Trapping "the index was outside the bounds of the array" error

[anon77170705]

@CarlBarnes

@anon77170705 is there some way to register with the RTL the Array Bounds Exception to be handled like an Access Violation? Or some RTL function to cause that exception?

There are 2 reasons why the EXCEPTION_ARRAY_BOUNDS_EXCEEDED is no catching by the hook function set to the PROP:LastChanceHook property:

1. The RTL exception handler filters some exceptions and returns DISPOSITION_CONTINUE_SEARCH before showing them to the hook function and to the RTL internal exception stuff. Exceptions which are filtered are debug exceptions (e.g. EXCEPTION_BREAKPOINT) to allow the debugger do its work, known .NET internal exceptions - otherwise the AppGen could not work, and some others. Also, there are exceptions which the RTL is processing internally only without invoking the hook function.
2. Windows not passes some exceptions to the SEH handlers chain. The EXCEPTION_ARRAY_BOUNDS_EXCEEDED exception is among them. Such exceptions can be caught using another mechanism: vectored exception handling. The RTL uses VEH but not to catch EXCEPTION_ARRAY_BOUNDS_EXCEEDED. Also, it’s need to call the SetErrorMode function with the SEM_NOGPFAULTERRORBOX parameter to turn off default processing of such exceptions.

I could modify my variant of the RTL to allow catch exceptions initiated by program’s components by calling to RaiseException. It’s need to divide the exception filter function to two parts: one is calling before invoking possible hook function and other one - after. Also, I could route all exceptions caught by VEH mechanism to main exception stuff. Some time is required for that.

@CarlBarnes

Seems like it would be a nice Project Option to have those Runtime Checks throw an Exception with a good name like “Array Bounds Exceeded” instead of showing the Runtime Error window with “Index Out of Range”

I do not see reasons for that.