[cxx-interop] Allow Swift to access non-public C++ members #79093
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This patch introduces an a C++ class annotation, SWIFT_PRIVATE_FILEID,
which will specify where Swift extensions of that class will be allowed
to access its non-public members, e.g.:
class SWIFT_PRIVATE_FILEID("MyModule/MyFile.swift") Foo { ... };
The goal of this feature is to help C++ developers incrementally migrate
the implementation of their C++ classes to Swift, without breaking
encapsulation and indiscriminately exposing those classes' private and
protected fields.
rdar://137764620
j-hui
requested review from
zoecarver,
hyp,
egorzhdan,
Xazax-hun,
ian-twilightcoder,
hborla,
slavapestov and
xedin
as code owners
|
@swift-ci please smoke test |
DougGregor
reviewed
Feb 10, 2025
- Make StringRef("private_fileid:") a constexpr
- Move fileID handling code into SourceFile::FileIDStr class
- Document what is a valid fileID format
- Diagnose multiple/invalid SWIFT_PRIVATE_FILEID annotations
- Handle multiple SWIFT_PRIVATE_FILEID annotations, even though
it should not be valid (makes it robust against feature changes
and diagnostic implementation issues)
|
@swift-ci Please test |
|
Thanks for the feedback @DougGregor and @Xazax-hun ! I think I addressed most of the points; I'll add the test case that Gabor suggested tomorrow. I also think it would be nice to add a test case to ensure the diagnostics are behaving as expected. Test cases:
|
Xazax-hun
approved these changes
Feb 13, 2025
|
@swift-ci Please test |
|
@swift-ci Please test |
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@swift-ci please test windows platform |
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@swift-ci please test windows platform |
|
@swift-ci please test |
|
@swift-ci please smoke test |
j-hui
added
c++ interop
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This patch introduces an a C++ class annotation, SWIFT_PRIVATE_FILEID, which will specify where Swift extensions of that class will be allowed to access its non-public members, e.g.:
The goal of this feature is to help C++ developers incrementally migrate the implementation of their C++ classes to Swift, without breaking encapsulation and indiscriminately exposing those classes' private and protected fields.
rdar://137764620
This patch is a reimplementation of the feature work from #77726, which got too large to be properly tested and reviewed. I first proposed this feature on Swift Forums: https://forums.swift.org/t/feature-proposal-accessing-non-public-c-members-from-swift/76116.
For those reviewing: I'd like feedback one aspect of this feature/patch, which is the name of the annotation. Specifically, I'm worried about it being named "Swift private" because that that could be confused with the existing
swift_privateattribute (which tells ClangImporter not to import a field).Several other pieces of follow-up/concurrent work are needed (though none block this patch):
Those are not being imported yet. (This work was already done in [cxx-interop] Allow Swift extensions to access non-public C++ members #77726 so it should be pretty straightforward to port.)PR: [cxx-interop] Import non-public inherited members #79348