change backtrace sep from const char* to char

include/mruby.h

@@ -118,7 +118,7 @@ typedef struct {
   const char *filename;
   int lineno;
   struct RClass *klass;
-  const char *sep;
+  char sep;
   mrb_sym method_id;
 } mrb_backtrace_entry;
 

src/backtrace.c

@@ -19,7 +19,7 @@ struct backtrace_location_raw {
   int lineno;
   const char *filename;
   mrb_sym method_id;
-  const char *sep;
+  char sep;
   struct RClass *klass;
 };
 
@@ -28,7 +28,7 @@ struct backtrace_location {
   int lineno;
   const char *filename;
   const char *method;
-  const char *sep;
+  char sep;
   const char *class_name;
 };
 
@@ -58,7 +58,7 @@ print_backtrace_i(mrb_state *mrb, struct backtrace_location *loc, void *data)
 
   if (loc->method) {
     if (loc->class_name) {
-      fprintf(args->stream, ":in %s%s%s", loc->class_name, loc->sep, loc->method);
+      fprintf(args->stream, ":in %s%c%s", loc->class_name, loc->sep, loc->method);
     }
     else {
       fprintf(args->stream, ":in %s", loc->method);
@@ -88,7 +88,7 @@ get_backtrace_i(mrb_state *mrb, struct backtrace_location *loc, void *data)
 
     if (loc->class_name) {
       mrb_str_cat_cstr(mrb, str, loc->class_name);
-      mrb_str_cat_cstr(mrb, str, loc->sep);
+      mrb_str_cat(mrb, str, &loc->sep, 1);
     }
 
     mrb_str_cat_cstr(mrb, str, loc->method);
@@ -134,10 +134,10 @@ each_backtrace(mrb_state *mrb, mrb_int ciidx, mrb_code *pc0, each_backtrace_func
     if (loc.lineno == -1) continue;
 
     if (ci->target_class == ci->proc->target_class) {
-      loc.sep = ".";
+      loc.sep = '.';
     }
     else {
-      loc.sep = "#";
+      loc.sep = '#';
     }
 
     if (!loc.filename) {
@@ -241,7 +241,7 @@ print_backtrace_saved(mrb_state *mrb)
 
       method_name = mrb_sym2name(mrb, entry->method_id);
       if (entry->klass) {
-        fprintf(stream, ":in %s%s%s",
+        fprintf(stream, ":in %s%c%s",
                 mrb_class_name(mrb, entry->klass),
                 entry->sep,
                 method_name);
@@ -409,7 +409,7 @@ mrb_restore_backtrace(mrb_state *mrb)
 
       if (entry->klass) {
         mrb_str_cat_cstr(mrb, mrb_entry, mrb_class_name(mrb, entry->klass));
-        mrb_str_cat_cstr(mrb, mrb_entry, entry->sep);
+        mrb_str_cat(mrb, mrb_entry, &entry->sep, 1);
       }
 
       mrb_str_cat_cstr(mrb, mrb_entry, mrb_sym2name(mrb, entry->method_id));