[PATCH v2 0/1] MR10373: vbscript: Allow Property Let to accept VT_DISPATCH arguments.

[Francis De Brabandere (＠francisdb)]

When assigning an object (VT_DISPATCH) to a property, Wine looks for
Property Set. If only Property Let is defined, fall back to using it
with the object's default value. This allows code that uses Property Let
with object arguments (which extracts the default value) to work when
Property Set is not defined.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53844

--
  v2: vbscript: Pass VT_DISPATCH as-is to Property Let without extracting default value.
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10373

[PATCH v2 1/1] vbscript: Pass VT_DISPATCH v2 1/1 as-is to Property Let without extracting default value.

[Francis De Brabandere]

From: Francis De Brabandere <[e-mail]>

On Windows, Property Let receives the object (VT_DISPATCH) directly,
not its default value. Fix invoke_vbdisp to skip default-value
extraction in the Property Let/Set code path, and select the function
based on the dispatch flags instead of the value type.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=53844
---
 dlls/vbscript/tests/lang.vbs | 27 +++++++++++++++++++++++++++
 dlls/vbscript/vbdisp.c       |  4 ++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/dlls/vbscript/tests/lang.vbs b/dlls/vbscript/tests/lang.vbs
index c364f12c00b..897ccef135f 100644
--- a/dlls/vbscript/tests/lang.vbs
+++ b/dlls/vbscript/tests/lang.vbs
@@ -2108,6 +2108,7 @@ Class TestPropParam
     Public oDict
     Public gotNothing
     Public m_obj
+    Public m_objType
 
     Public Property Set bar(obj)
         Set m_obj = obj
@@ -2126,6 +2127,14 @@ Class TestPropParam
     Public Property Let ten(a,b,c,d,e,f,g,h,i,j)
         oDict = a & b & c & d & e & f & g & h & i & j
     End Property
+    Public Property Let objProp(aInput)
+        m_objType = getVT(aInput)
+        If IsObject(aInput) Then
+            Set m_obj = aInput
+        Else
+            m_obj = aInput
+        End If
+    End Property
 End Class
 
 Set x = new TestPropParam
@@ -2141,6 +2150,24 @@ Set x.foo("123") = Nothing
 call ok(x.oDict = "123","x.oDict = " & x.oDict & " expected 123")
 call ok(x.gotNothing=True,"x.gotNothing = " & x.gotNothing  & " expected true")
 
+' Property Let receives VT_DISPATCH argument as-is (does not extract default value)
+Set y = New EndTestClassWithProperty
+y.x = 42
+x.objProp = y
+call ok(x.m_objType = "VT_DISPATCH*", "Property Let aInput type: " & x.m_objType & " expected VT_DISPATCH*")
+call ok(x.m_obj = 42, "Property Let with object argument failed, m_obj = " & x.m_obj)
+
+' Property Let receives object without default property as VT_DISPATCH
+Set z = New EmptyClass
+x.objProp = z
+call ok(x.m_objType = "VT_DISPATCH*", "Property Let no-default aInput type: " & x.m_objType & " expected VT_DISPATCH*")
+
+' Set with only Property Let defined should fail (no fallback to Let)
+On Error Resume Next
+Set x.objProp = y
+call ok(Err.Number = 438, "Set Property Let only: Err.Number = " & Err.Number & " expected 438")
+On Error GoTo 0
+
 set x = new TestPropSyntax
 set x.prop = new TestPropSyntax
 set x.prop.prop = new TestPropSyntax
diff --git a/dlls/vbscript/vbdisp.c b/dlls/vbscript/vbdisp.c
index 0ede0cfd6ba..d9f0fbb856a 100644
--- a/dlls/vbscript/vbdisp.c
+++ b/dlls/vbscript/vbdisp.c
@@ -219,14 +219,14 @@ static HRESULT invoke_vbdisp(vbdisp_t *This, DISPID id, DWORD flags, BOOL extern
                 dp.rgvarg = buf;
             }
 
-            hres = get_propput_arg(This->desc->ctx, params, flags, dp.rgvarg, &needs_release);
+            hres = get_propput_arg(This->desc->ctx, params, flags | DISPATCH_PROPERTYPUTREF, dp.rgvarg, &needs_release);
             if(FAILED(hres)) {
                 if(dp.rgvarg != buf)
                     free(dp.rgvarg);
                 return hres;
             }
 
-            func = This->desc->funcs[id].entries[V_VT(dp.rgvarg) == VT_DISPATCH ? VBDISP_SET : VBDISP_LET];
+            func = This->desc->funcs[id].entries[(flags & DISPATCH_PROPERTYPUTREF) ? VBDISP_SET : VBDISP_LET];
             if(!func) {
                 FIXME("no letter/setter\n");
                 if(dp.rgvarg != buf)
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10373

[Francis De Brabandere (＠francisdb)]

On Thu Mar 19 14:33:53 2026 +0000, Francis De Brabandere wrote:
> changed this line in [version 2 of the diff](/wine/wine/-/merge_requests/10373/diffs?diff_id=252281&start_sha=ee453c3c4d4bce1c6b3b6f0b4560d121ccbfa4a1#18a8771bf91222ebfc4599f53729c95217a5ab51_2130_2131)
> Did some more windows tests and added some cases. Is this better?

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10373#note_132812

[PATCH v2 0/1] MR10373: vbscript: Pass VT_DISPATCH as-is to Property Let without extracting default value. - approved

[Jacek Caban (＠jacek)]

This merge request was approved by Jacek Caban.
-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10373