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(-)

2 files changed, 18 insertions, 0 deletions

diff --git a/ext/-test-/string/depend b/ext/-test-/string/depend
index 67dfd2289f..7db4465bf9 100644
--- a/ext/-test-/string/depend
+++ b/ext/-test-/string/depend
@@ -1000,6 +1000,7 @@ fstring.o: $(hdrdir)/ruby/backward/2/long_long.h
 fstring.o: $(hdrdir)/ruby/backward/2/stdalign.h
 fstring.o: $(hdrdir)/ruby/backward/2/stdarg.h
 fstring.o: $(hdrdir)/ruby/defines.h
+fstring.o: $(hdrdir)/ruby/encoding.h
 fstring.o: $(hdrdir)/ruby/intern.h
 fstring.o: $(hdrdir)/ruby/internal/anyargs.h
 fstring.o: $(hdrdir)/ruby/internal/arithmetic.h
@@ -1142,6 +1143,8 @@ fstring.o: $(hdrdir)/ruby/internal/variable.h
 fstring.o: $(hdrdir)/ruby/internal/warning_push.h
 fstring.o: $(hdrdir)/ruby/internal/xmalloc.h
 fstring.o: $(hdrdir)/ruby/missing.h
+fstring.o: $(hdrdir)/ruby/onigmo.h
+fstring.o: $(hdrdir)/ruby/oniguruma.h
 fstring.o: $(hdrdir)/ruby/ruby.h
 fstring.o: $(hdrdir)/ruby/st.h
 fstring.o: $(hdrdir)/ruby/subst.h
diff --git a/ext/-test-/string/fstring.c b/ext/-test-/string/fstring.c
index 30120b42f6..2374319fe3 100644
--- a/ext/-test-/string/fstring.c
+++ b/ext/-test-/string/fstring.c
@@ -1,4 +1,5 @@
 #include "ruby.h"
+#include "ruby/encoding.h"
 
 VALUE rb_fstring(VALUE str);
 
@@ -8,8 +9,22 @@ bug_s_fstring(VALUE self, VALUE str)
     return rb_fstring(str);
 }
 
+VALUE
+bug_s_rb_enc_interned_str(VALUE self, VALUE encoding)
+{
+    return rb_enc_interned_str("foo", 3, RDATA(encoding)->data);
+}
+
+VALUE
+bug_s_rb_enc_str_new(VALUE self, VALUE encoding)
+{
+    return rb_enc_str_new("foo", 3, RDATA(encoding)->data);
+}
+
 void
 Init_string_fstring(VALUE klass)
 {
     rb_define_singleton_method(klass, "fstring", bug_s_fstring, 1);
+    rb_define_singleton_method(klass, "rb_enc_interned_str", bug_s_rb_enc_interned_str, 1);
+    rb_define_singleton_method(klass, "rb_enc_str_new", bug_s_rb_enc_str_new, 1);
 }