[6.2][cxx-interop] Fix runtime crash passing FRTs as const FRT* #81096
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Explanation: There was an inconsistency between non-const and const FRT pointers. The former used Direct_Unowned the latter used Indirect calling convention. We want to use Direct_Unowned for both cases. The crash was the result of a calling convention mismatch between the SILFunctionType of a Swift closure and the SILFunctionType of the C++ function's formal parameter that is taking a function pointer. The compiler tried to insert a conversion between the two function types that does not exist and caused an assertion in debug compilers and miscompilation in production compilers. Issue: rdar://149398905 Risk: Low, the fix is targeted and we change to a well-tested behavior with non-const FRT pointers. Testing: Regression test added. Original PR: #81070 Reviewer: @j-hui
Xazax-hun
added
c++ interop
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@swift-ci please test |
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@swift-ci please test macOS |
j-hui
approved these changes
Apr 25, 2025
DougGregor
approved these changes
Apr 25, 2025
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Explanation: There was an inconsistency between non-const and const FRT pointers. The former used Direct_Unowned the latter used Indirect calling convention. We want to use Direct_Unowned for both cases. The crash was the result of a calling convention mismatch between the SILFunctionType of a Swift closure and the SILFunctionType of the C++ function's formal parameter that is taking a function pointer. The compiler tried to insert a conversion between the two function types that does not exist and caused an assertion in debug compilers and miscompilation in production compilers.
Issue: rdar://149398905
Risk: Low, the fix is targeted and we change to a well-tested behavior with non-const FRT pointers.
Testing: Regression test added.
Original PR: #81070
Reviewer: @j-hui