[Python-ideas] dictionary constructor should not allow duplicate keys

[Franklin? Lee]

On May 4, 2016 2:47 AM, "Pavol Lisy" <pavol.lisy at gmail.com> wrote:
>
> 2016-05-04 6:03 GMT+02:00, Nick Coghlan <ncoghlan at gmail.com>:
>
> > I was curious as to whether or not it was technically feasible to
> > implement this "duplicate keys" check solely for dict displays in
> > CPython without impacting other dict use cases, and it turns out it
> > should be.
>
> [...]
>
> > 1. Report a DeprecationWarning in 3.6
> > 2. Report a [RuntimeError? ValueError?] in 3.7+
>
> But what about SyntaxError instead of RuntimeError? Could it be easily
> done too?

Is it really a SyntaxError? The compiler knows what the source code means,
but it assumes that the meaning is not what you intended.
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