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

[Random832]

On Tue, May 3, 2016, at 22:22, Chris Angelico wrote:
> Whether constants get folded before this check, and whether {1:'x',
> 1.0:'y'} causes an error, can be implementation-defined.

For *general* constant folding, maybe, but what's the point of having it
if it doesn't apply to negative numbers and nonimaginary complex
numbers? How about tuple displays consisting of only numeric and string
literals, empty tuple displays, and tuple displays which themselves
satisfy this definition?