Mark strings returned by Symbol#to_s as chilled (#12065)

* Use FL_USER0 for ELTS_SHARED

This makes space in RString for two bits for chilled strings.

* Mark strings returned by `Symbol#to_s` as chilled

[Feature #20350]

`STR_CHILLED` now spans on two user flags. If one bit is set it
marks a chilled string literal, if it's the other it marks a
`Symbol#to_s` chilled string.

Since it's not possible, and doesn't make much sense to include
debug info when `--debug-frozen-string-literal` is set, we can't
include allocation source, but we can safely include the symbol
name in the warning message, making it much easier to find the source
of the issue.

Co-Authored-By: Étienne Barrié <etienne.barrie@gmail.com>

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Co-authored-by: Étienne Barrié <etienne.barrie@gmail.com>
Co-authored-by: Jean Boussier <jean.boussier@gmail.com>

0 files changed, 0 insertions, 0 deletions