[6.3][cxx-interop] Fix miscompilation for inferred shared references #86196
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…tance-refcounts [cxx-interop] Fix miscompilation for inferred shared references
…efcount-followup [cxx-interop] Fix missing implicit cast in synthesized code
Xazax-hun
added
c++ interop
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|
@swift-ci please test |
j-hui
approved these changes
Dec 24, 2025
DougGregor
approved these changes
Jan 5, 2026
| auto importRefCountOp = [&](const clang::CXXMethodDecl *op) { | ||
| auto importedOp = | ||
| cast<ValueDecl>(context.getClangModuleLoader()->importDeclDirectly(op)); | ||
| ImporterImpl.markMemberSynthesizedPerType(importedOp); |
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This "mark" seems to happen very late. Are we sure that we're preventing recursive cases from adding these twice?
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I think it should be fine in this case because we have some restrictions on the signature of the reference counting operations, so the import should not cascade into importing other types. We already started importing the reference counted type T and it should have the signature like (integral|void) operation(T *); and we should not import T again as part of importing this function. Let me know if you had a different concern in mind.
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Explanation: When the reference count operation is defined for a base class and that base class is not at offset 0 we need to do offset adjustments before calling the refcount operations. We did not do that. This PR adds clang stubs that will do correct codegen for the derived to base conversions to avoid the miscompilation. This is a similar strategy what we do for inherited member functions.
Issues: rdar://166227787
Original PRs: #86124, #86184
Risk: Medium, there is a change in how we handle shared reference annotations when only a base class is annotated but this is a case that was already buggy in many cases. On the other hand, synthesizing new/more code always have a slight risk of generating code that would not compile.
Testing: Added a compiler test.
Reviewers: @egorzhdan @j-hui