String for string literal is not resizable

4 files changed, 18 insertions, 1 deletions

diff --git a/ext/-test-/string/depend b/ext/-test-/string/depend
index 26720282b2..eeb4914346 100644
--- a/ext/-test-/string/depend
+++ b/ext/-test-/string/depend
@@ -1196,6 +1196,7 @@ fstring.o: $(hdrdir)/ruby/backward.h
 fstring.o: $(hdrdir)/ruby/backward/2/assume.h
 fstring.o: $(hdrdir)/ruby/backward/2/attributes.h
 fstring.o: $(hdrdir)/ruby/backward/2/bool.h
+fstring.o: $(hdrdir)/ruby/backward/2/gcc_version_since.h
 fstring.o: $(hdrdir)/ruby/backward/2/inttypes.h
 fstring.o: $(hdrdir)/ruby/backward/2/limits.h
 fstring.o: $(hdrdir)/ruby/backward/2/long_long.h
@@ -1358,6 +1359,8 @@ fstring.o: $(hdrdir)/ruby/oniguruma.h
 fstring.o: $(hdrdir)/ruby/ruby.h
 fstring.o: $(hdrdir)/ruby/st.h
 fstring.o: $(hdrdir)/ruby/subst.h
+fstring.o: $(top_srcdir)/internal/compilers.h
+fstring.o: $(top_srcdir)/internal/string.h
 fstring.o: fstring.c
 init.o: $(RUBY_EXTCONF_H)
 init.o: $(arch_hdrdir)/ruby/config.h
diff --git a/ext/-test-/string/fstring.c b/ext/-test-/string/fstring.c
index 2374319fe3..7ee14a8570 100644
--- a/ext/-test-/string/fstring.c
+++ b/ext/-test-/string/fstring.c
@@ -1,5 +1,6 @@
 #include "ruby.h"
 #include "ruby/encoding.h"
+#include "internal/string.h"
 
 VALUE rb_fstring(VALUE str);
 
@@ -10,6 +11,14 @@ bug_s_fstring(VALUE self, VALUE str)
 }
 
 VALUE
+bug_s_fstring_fake_str(VALUE self)
+{
+    static const char literal[] = "abcdefghijklmnopqrstuvwxyz";
+    struct RString fake_str;
+    return rb_fstring(rb_setup_fake_str(&fake_str, literal, sizeof(literal) - 1, 0));
+}
+
+VALUE
 bug_s_rb_enc_interned_str(VALUE self, VALUE encoding)
 {
     return rb_enc_interned_str("foo", 3, RDATA(encoding)->data);
@@ -25,6 +34,7 @@ void
 Init_string_fstring(VALUE klass)
 {
     rb_define_singleton_method(klass, "fstring", bug_s_fstring, 1);
+    rb_define_singleton_method(klass, "fstring_fake_str", bug_s_fstring_fake_str, 0);
     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);
 }
diff --git a/string.c b/string.c
index 13b63f023a..b3004624dd 100644
--- a/string.c
+++ b/string.c
@@ -428,7 +428,7 @@ rb_fstring(VALUE str)
         }
     }
 
-    if (!OBJ_FROZEN(str))
+    if (!FL_TEST_RAW(str, FL_FREEZE | STR_NOFREE))
         rb_str_resize(str, RSTRING_LEN(str));
 
     fstr = register_fstring(str, FALSE);
diff --git a/test/-ext-/string/test_fstring.rb b/test/-ext-/string/test_fstring.rb
index 5a3456c566..b7416ccbf3 100644
--- a/test/-ext-/string/test_fstring.rb
+++ b/test/-ext-/string/test_fstring.rb
@@ -49,6 +49,10 @@ class Test_String_Fstring < Test::Unit::TestCase
     assert_raise(TypeError) {fstr.singleton_class}
   end
 
+  def test_fake_str
+    assert_equal([*"a".."z"].join(""), Bug::String.fstring_fake_str)
+  end
+
   class S < String
   end