MicrosoftEdge / MicrosoftEdge/WebView2Feedback

Impossible to call COM-methods that expect NULL as interface pointer.

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bug priority-low tracked
Dominant language
PowerShell
Stars
526
Forks
67
PR merge metrics
No merged PRs in 30d

Description

Impossible to call COM-methods that expect NULL as interface pointer. Sofar we have worked around problem by passing COM-objects also for optional parameters.

Possibly we can work around this problem in ATL/C++ by altering call parameters in IDispatch-implementstion. There is probably some confusion between VT_NULL, VT_EMPTY and VT_ERROR.

Version
SDK: GA 1.0.622.22
Runtime: WebView2 Runtime GA
Framework: Win32
OS: All

AB#29930251

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Research direction

Start by reproducing a COM method call that expects a NULL interface pointer, then inspect the ATL/C++ IDispatch parameter handling described in the issue. Compare how VT_NULL, VT_EMPTY, and VT_ERROR are passed; done means optional interface parameters can receive NULL correctly without requiring substitute COM objects.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
api, desktop
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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