Use rb_String() instead of rb_funcall()

ext/ox/builder.c

@@ -708,9 +708,7 @@ static VALUE builder_text(int argc, VALUE *argv, VALUE self) {
         strip_invalid_chars = Qfalse;
     }
 
-    if (T_STRING != rb_type(v)) {
-        v = rb_funcall(v, ox_to_s_id, 0);
-    }
+    v = rb_String(v);
     i_am_a_child(b, true);
     append_string(b, StringValuePtr(v), RSTRING_LEN(v), xml_element_chars, RTEST(strip_invalid_chars));
 
@@ -730,9 +728,7 @@ static VALUE builder_cdata(VALUE self, VALUE data) {
     const char    *end;
     int            len;
 
-    if (T_STRING != rb_type(v)) {
-        v = rb_funcall(v, ox_to_s_id, 0);
-    }
+    v   = rb_String(v);
     str = StringValuePtr(v);
     len = (int)RSTRING_LEN(v);
     s   = str;
@@ -772,9 +768,7 @@ static VALUE builder_raw(VALUE self, VALUE text) {
     const char    *end;
     int            len;
 
-    if (T_STRING != rb_type(v)) {
-        v = rb_funcall(v, ox_to_s_id, 0);
-    }
+    v   = rb_String(v);
     str = StringValuePtr(v);
     len = (int)RSTRING_LEN(v);
     s   = str;

ext/ox/dump.c

@@ -761,7 +761,7 @@ static void dump_obj(ID aid, VALUE obj, int depth, Out out) {
                 e.indent = -1;
                 out->w_end(out, &e);
             } else if (0 == strcmp("BigDecimal", classname)) {
-                volatile VALUE rs = rb_funcall(obj, ox_to_s_id, 0);
+                volatile VALUE rs = rb_String(obj);
 
                 e.type = BigDecimalCode;
                 out->w_start(out, &e);

ext/ox/obj_load.c

@@ -794,7 +794,7 @@ static void debug_stack(PInfo pi, const char *comment) {
                 if (HashCode == h->type) {
                     VALUE v;
 
-                    v   = rb_funcall2(h->var, rb_intern("to_s"), 0, 0);
+                    v   = rb_String(h->var);
                     key = StringValuePtr(v);
                 } else if (ObjectCode == (h - 1)->type || ExceptionCode == (h - 1)->type ||
                            RangeCode == (h - 1)->type || StructCode == (h - 1)->type) {

ext/ox/ox.c

@@ -73,7 +73,6 @@ ID ox_start_element_id;
 ID ox_string_id;
 ID ox_text_id;
 ID ox_to_c_id;
-ID ox_to_s_id;
 ID ox_value_id;
 
 VALUE ox_encoding_sym;
@@ -1445,7 +1444,6 @@ void Init_ox() {
     ox_string_id            = rb_intern("string");
     ox_text_id              = rb_intern("text");
     ox_to_c_id              = rb_intern("to_c");
-    ox_to_s_id              = rb_intern("to_s");
     ox_value_id             = rb_intern("value");
 
     encoding_id = rb_intern("encoding");

ext/ox/ox.h

@@ -205,7 +205,6 @@ extern ID ox_start_element_id;
 extern ID ox_string_id;
 extern ID ox_text_id;
 extern ID ox_to_c_id;
-extern ID ox_to_s_id;
 extern ID ox_value_id;
 
 extern rb_encoding *ox_utf8_encoding;

ext/ox/slotcache.c

@@ -145,7 +145,7 @@ static void slot_print(SlotCache c, unsigned int depth) {
                     vs   = "undefined";
                     clas = "";
                 } else {
-                    VALUE rs = rb_funcall2((*cp)->value, rb_intern("to_s"), 0, 0);
+                    VALUE rs = rb_String((*cp)->value);
 
                     vs   = StringValuePtr(rs);
                     clas = rb_class2name(rb_obj_class((*cp)->value));

test/c/cache16.c

@@ -90,7 +90,7 @@ static void slot_print(Cache16 c, unsigned int depth) {
 }
 
 static void v2s(VALUE v, char *buf, unsigned long len) {
-    VALUE rs = rb_funcall2(v, rb_intern("to_s"), 0, 0);
+    VALUE rs = rb_String(v);
 
     snprintf(buf, len, "%s", StringValuePtr(rs));
 }

test/c/cache_test.c

@@ -44,7 +44,7 @@ void ox_cache_test() {
                 *slot = v;
             }
         } else {
-            VALUE rs = rb_funcall2(v, rb_intern("to_s"), 0, 0);
+            VALUE rs = rb_String(v);
 
             printf("*** get on '%s' returned '%s' (%s)\n", *d, StringValuePtr(rs), rb_class2name(rb_obj_class(v)));
         }