🍒[cxx-interop] C++ reference types are not AnyObjects
#76720
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C++ foreign reference types have custom reference counting mechanisms, so they cannot conform to `AnyObject`. Currently Swift's type system treats C++ FRTs as `AnyObject`s on non-Darwin platforms, which is incorrect. This change makes sure the behavior is consistent with Darwin platform, i.e. a cast of C++ FRT to `AnyObject` is rejected by the typechecker. rdar://136664617 (cherry picked from commit 82c076c)
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@swift-ci please test |
DougGregor
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Sep 26, 2024
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Explanation: C++ foreign reference types have custom reference counting mechanisms, so they cannot conform to
AnyObject. Currently Swift's type system treats C++ FRTs asAnyObjects on non-Darwin platforms, which is incorrect. This change makes sure the behavior is consistent with Darwin platform, i.e. a cast of C++ FRT toAnyObjectis rejected by the typechecker.Scope: Makes sure the special typechecker rule for FRTs is applied when Obj-C interop is disabled.
Risk: Low, only takes effect when Obj-C interop is disabled, and FRTs are used.
Testing: Enabled an existing compiler test on Linux and Windows.
Issue: rdar://136664617
Reviewer: @Xazax-hun
Original PR: #74185