Change the return type of `mrb_check_intern()` and friends.

They used to return `mrb_value` but now return `mrb_sym` for consistency
with other `intern` functions. If symbols are not defined, `check`
functions return `0`, instead of `nil` in the past.

It causes API incompatibility but I believe few people use those
functions out of the core, and those changes are very easy to handle,
hopefully.

include/mruby.h

@@ -1097,9 +1097,10 @@ MRB_API mrb_sym mrb_intern(mrb_state*,const char*,size_t);
 MRB_API mrb_sym mrb_intern_static(mrb_state*,const char*,size_t);
 #define mrb_intern_lit(mrb, lit) mrb_intern_static(mrb, (lit ""), mrb_strlen_lit(lit))
 MRB_API mrb_sym mrb_intern_str(mrb_state*,mrb_value);
-MRB_API mrb_value mrb_check_intern_cstr(mrb_state*,const char*);
-MRB_API mrb_value mrb_check_intern(mrb_state*,const char*,size_t);
-MRB_API mrb_value mrb_check_intern_str(mrb_state*,mrb_value);
+/* mrb_check_intern series functions returns 0 if the symbol is not defined */
+MRB_API mrb_sym mrb_check_intern_cstr(mrb_state*,const char*);
+MRB_API mrb_sym mrb_check_intern(mrb_state*,const char*,size_t);
+MRB_API mrb_sym mrb_check_intern_str(mrb_state*,mrb_value);
 MRB_API const char *mrb_sym_name(mrb_state*,mrb_sym);
 MRB_API const char *mrb_sym_name_len(mrb_state*,mrb_sym,mrb_int*);
 MRB_API const char *mrb_sym_dump(mrb_state*,mrb_sym);

mrbgems/mruby-bin-debugger/tools/mrdb/apibreak.c

@@ -151,7 +151,7 @@ compare_break_method(mrb_state *mrb, mrb_debug_breakpoint *bp, struct RClass *cl
       }
 
       sc = mrb_class_get(mrb, method_p->class_name);
-      ssym = mrb_symbol(mrb_check_intern_cstr(mrb, method_p->method_name));
+      ssym = mrb_check_intern_cstr(mrb, method_p->method_name);
       m = mrb_method_search_vm(mrb, &sc, ssym);
       if (MRB_METHOD_UNDEF_P(m)) {
         return MRB_DEBUG_OK;

src/class.c

@@ -356,11 +356,9 @@ mrb_vm_define_class(mrb_state *mrb, mrb_value outer, mrb_value super, mrb_sym id
 MRB_API mrb_bool
 mrb_class_defined(mrb_state *mrb, const char *name)
 {
-  mrb_value sym = mrb_check_intern_cstr(mrb, name);
-  if (mrb_nil_p(sym)) {
-    return FALSE;
-  }
-  return mrb_const_defined(mrb, mrb_obj_value(mrb->object_class), mrb_symbol(sym));
+  mrb_sym sym = mrb_check_intern_cstr(mrb, name);
+  if (!sym) return FALSE;
+  return mrb_const_defined(mrb, mrb_obj_value(mrb->object_class), sym);
 }
 
 MRB_API mrb_bool
@@ -372,11 +370,9 @@ mrb_class_defined_id(mrb_state *mrb, mrb_sym name)
 MRB_API mrb_bool
 mrb_class_defined_under(mrb_state *mrb, struct RClass *outer, const char *name)
 {
-  mrb_value sym = mrb_check_intern_cstr(mrb, name);
-  if (mrb_nil_p(sym)) {
-    return FALSE;
-  }
-  return mrb_const_defined_at(mrb, mrb_obj_value(outer), mrb_symbol(sym));
+  mrb_sym sym = mrb_check_intern_cstr(mrb, name);
+  if (!sym) return FALSE;
+  return mrb_const_defined_at(mrb, mrb_obj_value(outer), sym);
 }
 
 MRB_API mrb_bool

src/symbol.c

@@ -289,24 +289,24 @@ mrb_intern_str(mrb_state *mrb, mrb_value str)
   return mrb_intern(mrb, RSTRING_PTR(str), RSTRING_LEN(str));
 }
 
-MRB_API mrb_value
+MRB_API mrb_sym
 mrb_check_intern(mrb_state *mrb, const char *name, size_t len)
 {
   mrb_sym sym;
 
   sym_validate_len(mrb, len);
   sym = find_symbol(mrb, name, len, NULL);
-  if (sym > 0) return mrb_symbol_value(sym);
-  return mrb_nil_value();
+  if (sym > 0) return sym;
+  return 0;
 }
 
-MRB_API mrb_value
+MRB_API mrb_sym
 mrb_check_intern_cstr(mrb_state *mrb, const char *name)
 {
   return mrb_check_intern(mrb, name, strlen(name));
 }
 
-MRB_API mrb_value
+MRB_API mrb_sym
 mrb_check_intern_str(mrb_state *mrb, mrb_value str)
 {
   return mrb_check_intern(mrb, RSTRING_PTR(str), RSTRING_LEN(str));