CNA-BUG-238: Win32Window's CnaPlatformWindow.Owned property is written and removed but never read, and its comment misdescribes AdoptWindowHandle

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

The kOwnedWindowProperty is set on every CNA-created HWND and removed on destroy but read nowhere; its comment says it lets AdoptWindowHandle refuse an owned window, whereas adoption returns a borrowed wrapper sharing the owner's id.

Identifier

CNA-BUG-238

Category

Bug

Subsystem

Documentation & release tooling

Status

Open

Verified against

CNA 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

Severity

Low (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

The CnaPlatformWindow.Owned window property and its documentation in CNA::Platform::Win32::Win32Window

Expected behaviour

A window property CNA sets on every owned HWND, with a comment explaining what reads it, should either be read for that purpose or not be described as one.

Actual behaviour at TARGET

Win32Window calls SetPropW(hwnd_, kOwnedWindowProperty, ...) after CreateWindowExW and RemovePropW on teardown, and its comment says the property is “so AdoptWindowHandle can refuse to adopt a window the platform already owns.” No GetPropW reads it anywhere. Win32Platform::AdoptWindowHandle does not consult the property: for a known HWND it finds the id in windows_ and returns a borrowed wrapper that shares the owner's id, and Win32WindowTest.LegacyTokenRoundTripsThroughAdoption asserts exactly that (adopted->GetId() == window->GetId()). The property is dead, and its comment describes behaviour the code does not implement.

Source locations

• modules/platform/src/Win32/Win32Window.cpp — kOwnedWindowProperty SetPropW/RemovePropW and the comment; no GetPropW
• modules/platform/src/Win32/Win32Platform.cpp — AdoptWindowHandle returns a borrowed wrapper for a known HWND, not a refusal
• modules/platform/tests/CNA/Platform/Win32WindowTests.cpp — LegacyTokenRoundTripsThroughAdoption asserts the shared id

Evidence

Checked by reading the property's SetPropW/RemovePropW sites, AdoptWindowHandle and the adoption test, and searching the Win32 sources for GetPropW (none) at 009d40f5. Not executed. The Development Win32 page records the same maintainer note.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

LegacyTokenRoundTripsThroughAdoption and AdoptedWindowDoesNotDestroy pin the borrow-and-share-id behaviour; no test reads the owned property.

Regression test

Either remove the property and correct the comment, or make AdoptWindowHandle read it and behave as the comment says; a test should then assert whichever contract is chosen.

Blast radius

Maintainers of Win32 window adoption who trust the comment; no runtime effect, since nothing reads the property.

Workaround

No workaround is known.