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 <[email protected]>

---------

Co-authored-by: Étienne Barrié <[email protected]>
Co-authored-by: Jean Boussier <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/prism_compile.c b/prism_compile.c
index f4a35fa429..fe5fde8d63 100644
--- a/prism_compile.c
+++ b/prism_compile.c
@@ -3382,7 +3382,7 @@ pm_compile_builtin_attr(rb_iseq_t *iseq, const pm_scope_node_t *scope_node, cons
         }
 
         VALUE symbol = pm_static_literal_value(iseq, argument, scope_node);
-        VALUE string = rb_sym_to_s(symbol);
+        VALUE string = rb_sym2str(symbol);
 
         if (strcmp(RSTRING_PTR(string), "leaf") == 0) {
             ISEQ_BODY(iseq)->builtin_attrs |= BUILTIN_ATTR_LEAF;