Program logic bugs vs input/environmental errors

[Walter Bright via Digitalmars-d]

On 10/1/2014 6:44 AM, Bruno Medeiros wrote:
> This is incorrect.
>
> Yes, the primary purpose of Exceptions is not for debugging, but to report
> exceptional state to the user (or some other component of the system).
>
> But they also have a purpose for debugging, particularly the stack traces of
> exceptions. Take what you said:
>
> "Failure to respond properly to an input/environmental error is a bug.
> But the input/environmental error is not a bug. If it was, then the
> program should assert on the error, not throw. "
>
> So, some component/function Foo detects an environmental error, and throws and
> Exception, accordingly. Foo is not responsible for handling these errors, but
> some other component is.
>
> Component/function Bar is the one that should handle such an error (for example,
> it should display a dialog to the user, and continue the application). But due
> to a bug, it doesn't do so, and the Exception goes all the way through main().

This is like saying "if statements are for debugging".


> The programmer notices this happening, and clearly recognizes it's a bug (but
> doesn't know where the bug is, doesn't know that it's Bar that should be
> handling it). Now, what is best, to just have the Exception message (something
> like "File not found") displayed to the programmer - or even an end-user that
> could report a bug -, or to have the stack trace of the Exception so that the
> programmer can more easily look at which function should be handling it?

Would you agree that every time DMD reports a syntax error in user code, it 
should also include a stack trace of the DMD source code to where in DMD it 
reported the error?