Worst ideas/features in programming languages?

[user1234]

On Tuesday, 12 October 2021 at 21:38:48 UTC, Timon Gehr wrote:
> On 10/11/21 5:59 PM, Atila Neves wrote:
>> ...
>
> This is likely to be incomplete or overly abstract, but here's 
> my approximate take:
>
>> * Worst features implemented in a non-toy language
>
> - unsound type system
> - undefined behavior for categories of errors other than memory 
> corruption
> - inappropriately nondeterministic semantics
> - mutable aliasing by default (mutability is fine, aliasing is 
> the issue)
> - pointer arithmetic without appropriate type system support
> - imprecise type system (>40 years behind state of the art)
> - non-orthogonal language definition
> - null pointers without appropriate type system support
> - Turing-complete constructors

Please mention the language for each point. I think that 
"inappropriately nondeterministic semantics" can be JS.