use mrb_str_new_lit instead of mrb_str_new for C string literals

mrbgems/mruby-bin-mruby/tools/mruby/mruby.c

@@ -217,7 +217,7 @@ main(int argc, char **argv)
     }
     else {
       mrbc_filename(mrb, c, "-e");
-      mrb_gv_set(mrb, zero_sym, mrb_str_new(mrb, "-e", 2));
+      mrb_gv_set(mrb, zero_sym, mrb_str_new_lit(mrb, "-e"));
       v = mrb_load_string_cxt(mrb, args.cmdline, c);
     }
   }

mrbgems/mruby-sprintf/src/sprintf.c

@@ -84,7 +84,7 @@ mrb_fix2binstr(mrb_state *mrb, mrb_value x, int base)
     val &= 0x3ff;
 
   if (val == 0) {
-    return mrb_str_new(mrb, "0", 1);
+    return mrb_str_new_lit(mrb, "0");
   }
   *--b = '\0';
   do {

mrbgems/mruby-struct/src/struct.c

@@ -442,7 +442,7 @@ static mrb_value
 inspect_struct(mrb_state *mrb, mrb_value s, int recur)
 {
   const char *cn = mrb_class_name(mrb, mrb_obj_class(mrb, s));
-  mrb_value members, str = mrb_str_new(mrb, "#<struct ", 9);
+  mrb_value members, str = mrb_str_new_lit(mrb, "#<struct ");
   mrb_value *ptr, *ptr_members;
   mrb_int i, len;
 

src/string.c

@@ -2406,7 +2406,7 @@ mrb_str_inspect(mrb_state *mrb, mrb_value str)
 {
     const char *p, *pend;
     char buf[CHAR_ESC_LEN + 1];
-    mrb_value result = mrb_str_new(mrb, "\"", 1);
+    mrb_value result = mrb_str_new_lit(mrb, "\"");
 
     p = RSTRING_PTR(str); pend = RSTRING_END(str);
     for (;p < pend; p++) {