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From: "cuzdav at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/106275] unordered_map with std::string key,
 std::hash<std::string>, and custom equality predicate weirdness
Date: Wed, 13 Jul 2022 16:28:27 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106275

--- Comment #6 from Chris Uzdavinis <cuzdav at gmail dot com> ---
Thank you for the information.  If the equality comparison function is slow
enough, the large number of extra calls may not be an optimization.=20=20

While looking into it, the vastly different runtime behavior of it jumped o=
ut
to me as an indication of a problem, and seemed to be the answer to why
internal tests drew my attention to this in the first place.  (Behavior is
normal without this optimization, but tests complained with it.)  But now I
understand it better, being a combination of the new behavior and
characteristics of the custom predicate in "real code" of which this is a
minimization.  The extra calls are a symptom, not a cause.=