Issue #20350 has been updated by Eregon (Benoit Daloze).
I added this to the dev meeting:
https://bugs.ruby-lang.org/issues/20336#note-8
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Feature #20350: Return chilled string from Symbol#to_s
https://bugs.ruby-lang.org/issues/20350#change-107805
* Author: Dan0042 (Daniel DeLorme)
* Status: Open
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During Ruby 2.7 development there was an attempt to return a frozen string from
Symbol#to_s (#16150#note-22)
This had to be rolled back due to incompatibility, but now we have chilled strings
(#20205)
Symbol#to_s can safely return a chilled string, giving developers time to fix warnings
before switching to a frozen string.
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