Fix bug in COM interface chain support #3060
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The definition of a COM interface may inherit from another interface. These are known as "interface chains". The `#[implement]` macro allows designers to specify only the minimal set of interface chains that are needed for a given COM object implementation. The `#[implement]` macro (and the `#[interface]` macro) work together to pull in the implementations of all interfaces along the chain. Unfortunately there is a bug in the implementation of `QueryInterface` for interface chains. The current `QueryInterface` implementation will only check the IIDs of the interfaces at the root of the chian, i.e. the "most-derived" interface. `QueryInterface` will not search the IIDs of interfaces that are in the inheritance chain. This bug is demonstrated (detected) by the new unit tests in `crates/tests/implement_core/src/com_chain.rs`. This PR fixes the bug by generating an `fn matches()` method that checks the current IID and then checks the parent interface (if any) by calling its `match()` method. This fixes the unit test.
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'matches' definitely needs to check parent IIDs. |
dpaoliello
approved these changes
May 29, 2024
arlosi
approved these changes
May 29, 2024
wravery
approved these changes
May 29, 2024
kennykerr
reviewed
Jun 4, 2024
| // QueryInterface to work correctly for all interfaces in an inheritance chain, e.g. | ||
| // IFoo3 derives from IFoo2 derives from IFoo. | ||
| // | ||
| // We avoid matching IUnknown because object identity depends on the uniqueness of the IUnknown pointer. |
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May be worth adding a test for this. #3069
mati865
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Jun 15, 2024
The definition of a COM interface may inherit from another interface. These are known as "interface chains". The `#[implement]` macro allows designers to specify only the minimal set of interface chains that are needed for a given COM object implementation. The `#[implement]` macro (and the `#[interface]` macro) work together to pull in the implementations of all interfaces along the chain. Unfortunately there is a bug in the implementation of `QueryInterface` for interface chains. The current `QueryInterface` implementation will only check the IIDs of the interfaces at the root of the chian, i.e. the "most-derived" interface. `QueryInterface` will not search the IIDs of interfaces that are in the inheritance chain. This bug is demonstrated (detected) by the new unit tests in `crates/tests/implement_core/src/com_chain.rs`. This PR fixes the bug by generating an `fn matches()` method that checks the current IID and then checks the parent interface (if any) by calling its `match()` method. This fixes the unit test. Co-authored-by: Arlie Davis <ardavis@microsoft.com>
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The definition of a COM interface may inherit from another interface. These are known as "interface chains". The
#[implement]macro allows designers to specify only the minimal set of interface chains that are needed for a given COM object implementation. The#[implement]macro (and the#[interface]macro) work together to pull in the implementations of all interfaces along the chain.Unfortunately there is a bug in the implementation of
QueryInterfacefor interface chains. The currentQueryInterfaceimplementation will only check the IIDs of the interfaces at the root of the chian, i.e. the "most-derived" interface.QueryInterfacewill not search the IIDs of interfaces that are in the inheritance chain.This bug is demonstrated (detected) by the new unit tests in
crates/tests/implement_core/src/com_chain.rs. This PR fixes the bug by generating anfn matches()method that checks the current IID and then checks the parent interface (if any) by calling itsmatch()method. This fixes the unit test.