self-referential Dict-key crashes Julia

[mauro3]

a=Dict();
a[a]=5;
a[a]=6; # stack overflow

Note, this works with ObjectIdDict. The stack overflow still happens after the fix #3066. This issue is somewhat related to #3847.

[JeffBezanson]

I'm not sure this is a real issue. Simply mutating values used as dict keys already causes problems. As for reference cycles, I suspect it is not worth the trouble and overhead to require all == and hash methods to handle them.

[kmsquire]

Does Julia actually crash?

On Wednesday, June 11, 2014, Jeff Bezanson [email protected] wrote:

I'm not sure this is a real issue. Simply mutating values used as dict
keys already causes problems. As for reference cycles, I suspect it is not
worth the trouble and overhead to require all == and hash methods to handle
them.

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Reply to this email directly or view it on GitHub
#7217 (comment).

[mauro3]

You can close this, I don't need a fix, just something I stumbled upon.

How would something similar show up with ==?

And no, no crash, just a stack overflow. (I just copied the title from #3847...)

[JeffBezanson]

== would have to be able to compare objects with reference cycles; that's required for table lookup.