Re: Undefined behaviour in C23

On 20/08/2025 14:06, John wrote:


> When a language is 50 years old and there is a mountain of legacy code that


> they really don't want to break, it accumulates a lot of cruft. If we were
> starting now we'd get something more like Go.
>
> On the other hand, there's the python approach in which they deprecate and
> remove little used and crufty features, but old python code doesn't work any
> more unless you go back and update it every year or two. -John]






Legacy behaviour and undefined behaviour are orthogonal concepts.




Any language ought to have fully defined behaviour: even if the
definition is simply "syntax error" or "the program exits with a
suitable error message". A language can be extended with new
constructs and new functions: then the behaviour changes from "syntax
error" or "error message" to the new functionality.


Whether or not old behaviour is preserved is a completely
separate issue.


\--
Martin


Dr Martin Ward | Email: [martin@gkc.org.uk](mailto:martin@gkc.org.uk) | <http://www.gkc.org.uk>
G.K.Chesterton site: <http://www.gkc.org.uk/gkc> | Erdos number: 4

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