Hash broken for unions, intersections, differences, and symmetric differences of sets

[saraedum]

The following code raises an exception

sage: S=Set(ZZ).union(Set([infinity]))
sage: hash(S)
Traceback (most recent call last):
...
RuntimeError: maximum recursion depth exceeded

The same should happen for intersections, differences, and symmetric differences.

Component: combinatorics

Keywords: hash, set, sd59

Author: Julian Rueth

Branch/Commit: 05ed037

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/14432

[saraedum]

Attachment: trac_14432.patch.gz

[saraedum]

Author: Julian Rueth

[saraedum]

comment:2

I do not have access to a 32-bit machine right now. Could someone fill in the missing hash values? Is there a way to compute them from the 64-bit values btw?

[saraedum]

comment:3

I decided to remove some duplicated code rather than adding a __hash__ method to all the implementations - hope that is ok.

[tscrim]

comment:4

To test hashing, it is better to do tests like hash(s) == hash(s) that do not depend upon the specific value but instead show that the object is hashable and it's value does not change.

[saraedum]

comment:5

That's a good point. Thanks for the input. I will change my patch accordingly.

[saraedum]

Branch: u/saraedum/ticket/14432

[nathanncohen]

Commit: e851c6f

[nathanncohen]

comment:9

This patch does not apply cleanly on 5.13.beta0. And it's probably because it contains many dependencies #14482 O_o

~/sage$ git fetch trac u/saraedum/ticket/14432:hash
remote: Counting objects: 17, done.
remote: Compressing objects: 100% (12/12), done.
remote: Total 12 (delta 10), reused 0 (delta 0)
Unpacking objects: 100% (12/12), done.
From ssh://trac.sagemath.org:2222/sage
 * [new branch]      u/saraedum/ticket/14432 -> hash
~/sage$ git merge hash
Auto-merging src/sage/sets/set.py
CONFLICT (content): Merge conflict in src/sage/sets/set.py
Auto-merging src/sage/doctest/forker.py
CONFLICT (content): Merge conflict in src/sage/doctest/forker.py
Auto-merging build/pkgs/sagenb/package-version.txt
CONFLICT (content): Merge conflict in build/pkgs/sagenb/package-version.txt
Auto-merging build/pkgs/sagenb/checksums.ini
CONFLICT (content): Merge conflict in build/pkgs/sagenb/checksums.ini
Auto-merging build/pkgs/sagenb/SPKG.txt
CONFLICT (content): Merge conflict in build/pkgs/sagenb/SPKG.txt
Automatic merge failed; fix conflicts and then commit the result.

---

Last 10 new commits:

[changeset:e851c6f]	fixed doctest for the hash of a union/intersection/... of sets
[changeset:10a3d1b]	(HEAD, refs/heads/stefan) Trac #14432: Fix `__hash__` for unions of sets
[changeset:a10bc4f]	Merge branch 'ticket/14482'
[changeset:fda55a9]	Merge branch 'u/saraedum/ticket/14482' of ssh://trac.sagemath.org:2222/sage into HEAD
[changeset:61236da]	Merge remote-tracking branch 'trac/public/sage-git/ticket/14482'
[changeset:08d3e94]	Merge branch 'ticket/14482'
[changeset:50e1ece]	Merge branch 'ticket/14482'
[changeset:1ca56cf]	Merge branch 'ticket/14273' into tip
[changeset:aa60895]	remove workaround for sagenb pull request 84 (#14273)
[changeset:133785b]	Merge branch 'ticket/14482' into tip

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

08f5ee0

Merge branch 'develop' into ticket/14432

[sagetrac-git]

Changed commit from e851c6f to 08f5ee0

[saraedum]

Changed keywords from hash, set to hash, set, sd59

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:16

I've made some minor review tweaks. If you're happy with them, then positive review.

---

New commits:

0190e4d

Some review changes to set.py.

[tscrim]

Changed commit from 08f5ee0 to 0190e4d

[tscrim]

Changed branch from u/saraedum/ticket/14432 to public/ticket/14432

[sagetrac-git]

Changed commit from 0190e4d to 05ed037

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

05ed037

Fix typo.

[vbraun]

Changed branch from public/ticket/14432 to 05ed037