encoding.c (rb_enc_get_index): return -1 for non-encoding capable objects

* Clarify logic and add spec.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64173 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 15 insertions, 8 deletions

diff --git a/encoding.c b/encoding.c
index eac4d7c50a..d130eb2612 100644
--- a/encoding.c
+++ b/encoding.c
@@ -793,24 +793,26 @@ rb_enc_get_index(VALUE obj)
 	obj = rb_sym2str(obj);
     }
     switch (BUILTIN_TYPE(obj)) {
-      as_default:
-      default:
       case T_STRING:
+      case T_SYMBOL:
       case T_REGEXP:
 	i = enc_get_index_str(obj);
 	break;
       case T_FILE:
 	tmp = rb_funcallv(obj, rb_intern("internal_encoding"), 0, 0);
-	if (NIL_P(tmp)) obj = rb_funcallv(obj, rb_intern("external_encoding"), 0, 0);
-	else obj = tmp;
-	if (NIL_P(obj)) break;
+	if (NIL_P(tmp)) {
+	    tmp = rb_funcallv(obj, rb_intern("external_encoding"), 0, 0);
+	}
+	if (is_data_encoding(tmp)) {
+	    i = enc_check_encoding(tmp);
+	}
+	break;
       case T_DATA:
 	if (is_data_encoding(obj)) {
 	    i = enc_check_encoding(obj);
 	}
-	else {
-	    goto as_default;
-	}
+	break;
+      default:
 	break;
     }
     return i;
diff --git a/spec/ruby/optional/capi/encoding_spec.rb b/spec/ruby/optional/capi/encoding_spec.rb
index 7661f2b68b..33587bf03a 100644
--- a/spec/ruby/optional/capi/encoding_spec.rb
+++ b/spec/ruby/optional/capi/encoding_spec.rb
@@ -147,6 +147,11 @@ describe "C-API Encoding function" do
     it "returns -1 as the index for immediates" do
       @s.send(@method, 1).should == -1
     end
+
+    it "returns -1 for an object without an encoding" do
+      obj = Object.new
+      @s.send(@method, obj).should == -1
+    end
   end
 
   describe "rb_enc_set_index" do