[EXPERIMENTAL] Make Symbol#to_s return a frozen String

* Always the same frozen String for a given Symbol.
* Avoids extra allocations whenever calling Symbol#to_s.
* See [Feature #16150]

1 files changed, 3 insertions, 2 deletions

diff --git a/string.c b/string.c
index 367773f0f5..3f0e69689c 100644
--- a/string.c
+++ b/string.c
@@ -10869,7 +10869,8 @@ sym_inspect(VALUE sym)
  *     sym.id2name   -> string
  *     sym.to_s      -> string
  *
- *  Returns the name or string corresponding to <i>sym</i>.
+ *  Returns a frozen string corresponding to <i>sym</i>.
+ *  The returned String is always the same String instance for a given Symbol.
  *
  *     :fred.id2name   #=> "fred"
  *     :ginger.to_s    #=> "ginger"
@@ -10879,7 +10880,7 @@ sym_inspect(VALUE sym)
 VALUE
 rb_sym_to_s(VALUE sym)
 {
-    return str_new_shared(rb_cString, rb_sym2str(sym));
+    return rb_sym2str(sym);
 }