Rework direct API for object comparison

Add sq_direct_is_equal() - this is not the same as invoking ObjCmp()
on objects. Logic of this comparison is the same as for <=> operator
and it can fail in certain scenarios.
Also for safety such comparison of non-numeric types (or classes
implementing _cmp metamethod) will be disabled soon.
In practice sq_direct_cmp() function was never needed - in all the
cases it was used for the equality check.
For this, implement sq_direct_is_equal() function.

Also simplify sq_direct_cmp() implementation - make it a thin wrapper
around SQVM::ObjCmp(). No need for extra logic that differs from VM
internals.

include/sqdirect.h

@@ -22,6 +22,7 @@ SQUIRREL_API SQRESULT sq_direct_get(HSQUIRRELVM v, const HSQOBJECT *obj, const H
 SQUIRREL_API SQBool sq_direct_tobool(const HSQOBJECT *o);
 
 SQUIRREL_API SQBool sq_direct_cmp(HSQUIRRELVM v, const HSQOBJECT *a, const HSQOBJECT *b, SQInteger *res);
+SQUIRREL_API bool sq_direct_is_equal(HSQUIRRELVM v, const HSQOBJECT *a, const HSQOBJECT *b);
 
 SQUIRREL_API SQRESULT sq_direct_getuserdata(const HSQOBJECT *obj, SQUserPointer *p, SQUserPointer *typetag=NULL);
 

sqrat/include/sqrat/sqratFunction.h

@@ -284,8 +284,7 @@ class Function  {
         if (GetVM() != so.GetVM())
             return false;
 
-        SQInteger res = 0;
-        return sq_direct_cmp(vm, &obj, &so.obj, &res) && (res==0);
+        return sq_direct_is_equal(vm, &obj, &so.obj);
     }
 
 private:

sqrat/include/sqrat/sqratObject.h

@@ -203,8 +203,7 @@ class Object {
         if (GetVM() != so.GetVM())
             return false;
 
-        SQInteger res = 0;
-        return sq_direct_cmp(vm, &obj, &so.obj, &res) && (res==0);
+        return sq_direct_is_equal(vm, &obj, &so.obj);
     }
 
     /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

squirrel/sqdirect.cpp

@@ -32,16 +32,23 @@ SQBool sq_direct_cmp(HSQUIRRELVM v, const HSQOBJECT *a, const HSQOBJECT *b, SQIn
     const SQObjectPtr &aPtr = static_cast<const SQObjectPtr &>(*a);
     const SQObjectPtr &bPtr = static_cast<const SQObjectPtr &>(*b);
 
-    SQObjectType t1 = sq_type(*a), t2 = sq_type(*b);
-    if (t1 == t2 || t1==OT_NULL || t2==OT_NULL || (sq_isnumeric(*a) && sq_isnumeric(*b)))
-    {
-      SQBool status = v->ObjCmp(aPtr, bPtr, *res);
-      assert(status);
-      return status;
-    }
-    return false;
+    return v->ObjCmp(aPtr, bPtr, *res);
 }
 
+
+bool sq_direct_is_equal(HSQUIRRELVM v, const HSQOBJECT *a, const HSQOBJECT *b)
+{
+    const SQObjectPtr &aPtr = static_cast<const SQObjectPtr &>(*a);
+    const SQObjectPtr &bPtr = static_cast<const SQObjectPtr &>(*b);
+
+    bool res = false;
+    bool status = v->IsEqual(aPtr, bPtr, res);
+    (void)status;
+    assert(status); // cannot fail
+    return res;
+}
+
+
 SQRESULT sq_direct_getuserdata(const HSQOBJECT *obj, SQUserPointer *p, SQUserPointer *typetag)
 {
     if (obj->_type != OT_USERDATA)