Sets of unhashable elements are broken

[maxale]

Documentation says "Sets with unhashable objects work, but with less functionality". However, this functionality is actually broken in at least two ways.

First, Sets of unhashable elements fail to recognize equal elements - for example

S = Set([factor(10),factor(10)])
print(S)

prints Set of elements of [2 * 5, 2 * 5], that is the resulting Set here contains two identical elements.

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Second, Set skips the first element when it's created from an iterator of unhashable elements:

S = Set( [i] for i in (1..5) )
print(list(S))

This code prints [[2], [3], [4], [5]], that is the first generated element [1] is missing.

A patch for the latter issue was proposed at https://ask.sagemath.org/question/62252/?answer=62285#post-id-62285 which however comes with an overhead.

Depends on #23324
Depends on #34387

CC: @tscrim

Component: misc

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/33932

[mantepse]

comment:1

See also #23324

[mkoeppe]

comment:2

The second example is fixed in #34387

[mkoeppe]

Dependencies: #34387

[mkoeppe]

comment:3

The first example is a dup of #23324.

[mkoeppe]

Changed dependencies from #34387 to #23324, #34387

[tscrim]

Reviewer: Travis Scrimshaw