Nope, it happens because of the aliasing of the hash value inside grep, but I'm not sure how.

Interesting effect. I see your output with plain perl v5.22.2 (from 2016) on Linux x86-64 and with Strawberry v5.14.2 (from 2011) on Windows 64 bit. So this seems to be an old, unsolved problem.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

In reply to Re^3: unexpected modify hash in a distance with grep { $_ } by afoken
in thread unexpected modify hash in a distance with grep { $_ } by leszekdubiel

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