jscript: Make compare2_values working with NULL BSTR's.

dlls/jscript/engine.c

@@ -304,7 +304,12 @@ static HRESULT equal2_values(VARIANT *lval, VARIANT *rval, BOOL *ret)
         *ret = V_R8(lval) == V_R8(rval);
         break;
     case VT_BSTR:
-        *ret = !strcmpW(V_BSTR(lval), V_BSTR(rval));
+        if(!V_BSTR(lval))
+            *ret = SysStringLen(V_BSTR(rval))?FALSE:TRUE;
+        else if(!V_BSTR(rval))
+            *ret = SysStringLen(V_BSTR(lval))?FALSE:TRUE;
+        else
+            *ret = !strcmpW(V_BSTR(lval), V_BSTR(rval));
         break;
     case VT_DISPATCH:
         return disp_cmp(V_DISPATCH(lval), V_DISPATCH(rval), ret);

dlls/jscript/tests/lang.js

@@ -896,4 +896,6 @@ ok(""+str === "test", "''+str = " + str);
 
 ok((function (){return 1;})() === 1, "(function (){return 1;})() = " + (function (){return 1;})());
 
+ok(createNullBSTR() === '', "createNullBSTR() !== ''");
+
 reportSuccess();

dlls/jscript/tests/run.c

@@ -73,6 +73,7 @@ DEFINE_EXPECT(GetItemInfo_testVal);
 #define DISPID_GLOBAL_OK            0x1004
 #define DISPID_GLOBAL_GETVT         0x1005
 #define DISPID_GLOBAL_TESTOBJ       0x1006
+#define DISPID_GLOBAL_NULL_BSTR     0x1007
 
 static const WCHAR testW[] = {'t','e','s','t',0};
 static const CHAR testA[] = "test";
@@ -283,6 +284,10 @@ static HRESULT WINAPI Global_GetDispID(IDispatchEx *iface, BSTR bstrName, DWORD
         *pid = DISPID_GLOBAL_TESTOBJ;
         return S_OK;
     }
+    if(!strcmp_wa(bstrName, "createNullBSTR")) {
+        *pid = DISPID_GLOBAL_NULL_BSTR;
+        return S_OK;
+    }
 
     if(strict_dispid_check)
         ok(0, "unexpected call %s\n", debugstr_w(bstrName));
@@ -429,6 +434,13 @@ static HRESULT WINAPI Global_InvokeEx(IDispatchEx *iface, DISPID id, LCID lcid,
         V_VT(pvarRes) = VT_DISPATCH;
         V_DISPATCH(pvarRes) = (IDispatch*)&testObj;
         return S_OK;
+
+    case DISPID_GLOBAL_NULL_BSTR:
+        if(pvarRes) {
+            V_VT(pvarRes) = VT_BSTR;
+            V_BSTR(pvarRes) = NULL;
+        }
+        return S_OK;
     }
 
     ok(0, "unexpected call %x\n", id);