Fix GH-17658: COMPersistHelper::LoadFromStream() can segfault #17659
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The actual fix is trivial, but to be able to test the behavior we have to introduce an own COM object, since existing persistable objects likely implement `IPersistInit`, not only `IPersist`. We also want to avoid further test dependencies on possibly unavailable objects, such as `Word.Application`. To this purposes, we add a small COM in-process server, which may be extended for other testing purposes. We keep it simple by implementing it in C++, but without using any more sophisticated frameworks like ATL. This component needs to be built explicitly (`nmake comtest.dll`), and also needs to be explicitly registered (`nmake register_comtest`). When no longer needed, it is possible to unregister the component (`nmake unregister_comtest`).
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The actual fix is trivial, but to be able to test the behavior we have to introduce an own COM object, since existing persistable objects likely implement
IPersistInit, not onlyIPersist. We also want to avoid further test dependencies on possibly unavailable objects, such asWord.Application.To this purposes, we add a small COM in-process server, which may be extended for other testing purposes. We keep it simple by implementing it in C++, but without using any more sophisticated frameworks like ATL.
This component needs to be built explicitly (
nmake comtest.dll), and also needs to be explicitly registered (nmake register_comtest). When no longer needed, it is possible to unregister the component (nmake unregister_comtest).TODO
COMPersistHelper::InitNew()in the test case to ensure thatIPersistInitis not implemented (might later happen by accident, rendering the regression test useless)