NFC: Work around 'cycle detected while resolving' warning #71032
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When building the Swift sources of the compiler many instances of the following
warning are emitted:
```
.../swift-project/swift/include/swift/AST/Attr.h:3075:10: warning: cycle detected while resolving 'iterator' in swift_name attribute for 'operator=='
bool operator==(iterator x) const { return x.attr == attr; }
^
```
These warnings were implemented in swiftlang#37940
and they indicate that Swift compiler is failing to import a clang decl because
of circular references. Something about the structure of some operator
declarations in C++ headers triggers this warning. I'm not sure what the
correct long term fix for this is, but in the meantime the build log for the
compiler is getting drowned in these warnings which makes it difficult to
notice and find other diagnostics. Since these declarations are getting dropped
instead of imported, we can simply hide them from the Swift compiler in the
first place by guarding the declarations with `#ifdef __swift__`.
|
@swift-ci please smoke test |
egorzhdan
approved these changes
Jan 22, 2024
tshortli
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Mar 3, 2024
Swift C++ interop has a bug where certain operator declarations cannot be imported successfully due to percieved circular references in the declarations. Since these declarations are already dropped by the ClangImporter, it's helpful to hide the declarations entirely from Swift to avoid spurious diagnostics that cannot be addressed. See swiftlang/swift#71032 for a similar workaround in the Swift compiler implementation.
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When building the Swift sources of the compiler many instances of the following warning are emitted:
These warnings were implemented in #37940 and they indicate that Swift compiler is failing to import a clang decl because of circular references. Something about the structure of some operator declarations in C++ headers triggers this warning. I'm not sure what the correct long term fix for this is, but in the meantime the build log for the compiler is getting drowned in these warnings which makes it difficult to notice and find other diagnostics. Since these declarations are getting dropped instead of imported, we can simply hide them from the Swift compiler in the first place by guarding the declarations with
#ifdef __swift__.