propsys: Support VT_LPWSTR in PropVariantChangeType.

dlls/propsys/propvar.c

@@ -257,6 +257,9 @@ HRESULT WINAPI PropVariantChangeType(PROPVARIANT *ppropvarDest, REFPROPVARIANT p
     FIXME("(%p, %p, %d, %d, %d): semi-stub!\n", ppropvarDest, propvarSrc,
           propvarSrc->vt, flags, vt);
 
+    if(vt == propvarSrc->vt)
+        return PropVariantCopy(ppropvarDest, propvarSrc);
+
     switch (vt)
     {
     case VT_I2:
@@ -325,6 +328,17 @@ HRESULT WINAPI PropVariantChangeType(PROPVARIANT *ppropvarDest, REFPROPVARIANT p
         }
         return hr;
     }
+    case VT_LPWSTR:
+    {
+        WCHAR *res;
+        hr = PropVariantToStringAlloc(propvarSrc, &res);
+        if (SUCCEEDED(hr))
+        {
+            ppropvarDest->vt = VT_LPWSTR;
+            ppropvarDest->u.pwszVal = res;
+        }
+        return hr;
+    }
     }
 
     switch (propvarSrc->vt)

dlls/propsys/tests/propsys.c

@@ -891,6 +891,42 @@ static void test_intconversions(void)
     ok(llval == -7, "got wrong value %s\n", debugstr_longlong(llval));
 }
 
+static void test_PropVariantChangeType_LPWSTR(void)
+{
+    PROPVARIANT dest, src;
+    HRESULT hr;
+
+    PropVariantInit(&dest);
+
+    src.vt = VT_NULL;
+    hr = PropVariantChangeType(&dest, &src, 0, VT_LPWSTR);
+    ok(hr == S_OK, "hr=%x\n", hr);
+    ok(dest.vt == VT_LPWSTR, "got %d\n", dest.vt);
+    ok(!lstrcmpW(dest.u.pwszVal, emptyW), "got %s\n", wine_dbgstr_w(dest.u.pwszVal));
+    PropVariantClear(&dest);
+    PropVariantClear(&src);
+
+    src.vt = VT_LPSTR;
+    src.u.pszVal = CoTaskMemAlloc(strlen(topic)+1);
+    strcpy(src.u.pszVal, topic);
+    hr = PropVariantChangeType(&dest, &src, 0, VT_LPWSTR);
+    ok(hr == S_OK, "hr=%x\n", hr);
+    ok(dest.vt == VT_LPWSTR, "got %d\n", dest.vt);
+    ok(!lstrcmpW(dest.u.pwszVal, topicW), "got %s\n", wine_dbgstr_w(dest.u.pwszVal));
+    PropVariantClear(&dest);
+    PropVariantClear(&src);
+
+    src.vt = VT_LPWSTR;
+    src.u.pwszVal = CoTaskMemAlloc( (lstrlenW(topicW)+1) * sizeof(WCHAR));
+    lstrcpyW(src.u.pwszVal, topicW);
+    hr = PropVariantChangeType(&dest, &src, 0, VT_LPWSTR);
+    ok(hr == S_OK, "hr=%x\n", hr);
+    ok(dest.vt == VT_LPWSTR, "got %d\n", dest.vt);
+    ok(!lstrcmpW(dest.u.pwszVal, topicW), "got %s\n", wine_dbgstr_w(dest.u.pwszVal));
+    PropVariantClear(&dest);
+    PropVariantClear(&src);
+}
+
 START_TEST(propsys)
 {
     test_PSStringFromPropertyKey();
@@ -902,4 +938,5 @@ START_TEST(propsys)
     test_PropVariantToStringAlloc();
     test_PropVariantCompare();
     test_intconversions();
+    test_PropVariantChangeType_LPWSTR();
 }