merge revision(s) 7e8a9af9db42a21f6a1125a29e98c45ff9d5833b: [Backport #17732]

	rb_enc_interned_str: handle autoloaded encodings

	If called with an autoloaded encoding that was not yet
	initialized, `rb_enc_interned_str` would crash with
	a NULL pointer exception.

	See: https://github.com/ruby/ruby/pull/4119#issuecomment-800189841
	---
	 encoding.c                        | 28 ++++++++++++----------------
	 ext/-test-/string/depend          |  3 +++
	 ext/-test-/string/fstring.c       | 15 +++++++++++++++
	 internal/encoding.h               |  3 +++
	 string.c                          |  4 ++++
	 test/-ext-/string/test_fstring.rb | 16 ++++++++++++++++
	 6 files changed, 53 insertions(+), 16 deletions(-)

1 files changed, 4 insertions, 0 deletions

diff --git a/string.c b/string.c
index 2a95a8357c..82850577ff 100644
--- a/string.c
+++ b/string.c
@@ -11505,6 +11505,10 @@ 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))) {
+        rb_enc_autoload(enc);
+    }
+
     struct RString fake_str;
     return register_fstring(rb_setup_fake_str(&fake_str, ptr, len, enc), TRUE);
 }