Return fstrings from `build_const_pathname`.

It's possible for `build_const_pathname` to be called when `rb_cString` is
still NULL. There is a fix-up step when `rb_cString` is initialized, but
it only applies to `fstring` instances.

1 files changed, 1 insertions, 2 deletions

diff --git a/variable.c b/variable.c
index aa1fdd022e..c6e1012bdd 100644
--- a/variable.c
+++ b/variable.c
@@ -202,8 +202,7 @@ build_const_pathname(VALUE head, VALUE tail)
     VALUE path = rb_str_dup(head);
     rb_str_cat2(path, "::");
     rb_str_append(path, tail);
-    OBJ_FREEZE(path);
-    return path;
+    return rb_fstring(path);
 }
 
 static VALUE