🍒[cxx-interop] Allow more C++ decls in public Swift interfaces #78084
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When compiling with C++ interop enabled, we enable extra safety checks to prevent library authors from accidentally exposing ABI-fragile C++ symbols in resilient Swift interfaces. The heuristic we use is overly strict, and it prevents the compiler from being able to typecheck various modules from their interfaces when C++ interop is enabled. Darwin and System are two of such modules. The underlying challenge is that there isn't a good distinction between C structs and C++ structs: whenever parsing a header file in C++ language mode, Clang assumes that every struct is a C++ struct. This relaxes the heuristic to allow exposing C-like structs in resilient interfaces. rdar://140203932 (cherry picked from commit 8859b62)
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@swift-ci please test |
DougGregor
approved these changes
Dec 10, 2024
Xazax-hun
approved these changes
Dec 10, 2024
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@swift-ci please test |
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Explanation: When compiling with C++ interop enabled, we enable extra safety checks to prevent library authors from accidentally exposing ABI-fragile C++ symbols in resilient Swift interfaces. The heuristic we use is overly strict, and it prevents the compiler from being able to typecheck various modules from their interfaces when C++ interop is enabled. Darwin and System are two of such modules. This relaxes the heuristic to allow exposing C-like structs, as well as constructors and fields of such structs in resilient interfaces.
Scope: Changes the resilience validation mechanism in the typechecker.
Risk: Low, this doesn't change the binaries that are produced by the compiler in any way.
Issue: rdar://140203932 & rdar://141124318
Reviewer: @Xazax-hun @tshortli
Original PRs: #78022 & #78057