[PATCH v2 1/4] propsys: Add VT_EMPTY support for PropVariantToStringAlloc().

[Jactry Zeng]

Superseded patch 158558 to 158560.

ChangeLog:
v2:
- Fix test failures on Windows 64 bit.(1/3)
- Use PropVariantToStringAlloc() for implementing PropVariantToString().(1/3)
- Use IsEqualGUID() for checking GUID instread of memcmp().(2/3)
- Add more tests for PropVariantToBuffer().(3/3)

Signed-off-by: Jactry Zeng 
---
 dlls/propsys/propvar.c       | 1 +
 dlls/propsys/tests/propsys.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/dlls/propsys/propvar.c b/dlls/propsys/propvar.c
index 0edf4621b3..396afbf050 100644
--- a/dlls/propsys/propvar.c
+++ b/dlls/propsys/propvar.c
@@ -314,6 +314,7 @@ HRESULT WINAPI PropVariantToStringAlloc(REFPROPVARIANT propvarIn, WCHAR **ret)

switch(propvarIn->vt)
     {
+        case VT_EMPTY:
         case VT_NULL:
             res = CoTaskMemAlloc(1*sizeof(WCHAR));
             res[0] = '\0';
diff --git a/dlls/propsys/tests/propsys.c b/dlls/propsys/tests/propsys.c
index a9c0a7730b..926dc3de71 100644
--- a/dlls/propsys/tests/propsys.c
+++ b/dlls/propsys/tests/propsys.c
@@ -641,6 +641,12 @@ static void test_PropVariantToStringAlloc(void)
     ok(!lstrcmpW(str, topicW), "got %s\n", wine_dbgstr_w(str));
     CoTaskMemFree(str);
     PropVariantClear(&prop);
+
+    prop.vt = VT_EMPTY;
+    hres = PropVariantToStringAlloc(&prop, &str);
+    ok(hres == S_OK, "returned %x\n", hres);
+    ok(!lstrcmpW(str, emptyW), "got %s\n", wine_dbgstr_w(str));
+    CoTaskMemFree(str);
 }

static void test_PropVariantCompare(void)