[Bug #20322] Fix rb_enc_interned_str_cstr null encoding

The documentation for `rb_enc_interned_str_cstr` notes that `enc` can be
a null pointer, but this currently causes a segmentation fault when
trying to autoload the encoding. This commit fixes the issue by checking
for NULL before calling `rb_enc_autoload`.

1 files changed, 1 insertions, 1 deletions

diff --git a/string.c b/string.c
index d9182530ed..a756523c4b 100644
--- a/string.c
+++ b/string.c
@@ -12122,7 +12122,7 @@ rb_interned_str_cstr(const char *ptr)
 VALUE
 rb_enc_interned_str(const char *ptr, long len, rb_encoding *enc)
 {
-    if (UNLIKELY(rb_enc_autoload_p(enc))) {
+    if (enc != NULL && UNLIKELY(rb_enc_autoload_p(enc))) {
         rb_enc_autoload(enc);
     }