NFC: make headers compatible with C++20 #67619
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In a downstream project we are using the Swift code as a library and compiling with C++20. This mostly works except for two backward incompatibilities introduced by C++20: * [P1008] disallows aggregate initialization when defaulted or deleted constructors are specified. This lead to a compilation error for aggregate initialization of `swift::Compilation::Result`. The backward and forward compatible fix for that is to provide a constructor turning aggregate initializations into a normal constructor call. * [P1185] introduces more candidates for overload resolution of comparison operator calls. As explained in [P1630], this leads in some cases to ambiguity compilation errors in C++20, which is exactly the case with `swift::ValueOwnershipKind`. The fix in this case is to remove some redundant operator calls conditionally on the `__cpp_impl_three_way_comparison` feature test macro, which [includes the papers mentioned above][feature_test]. [P1008]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1008r1.pdf [P1185]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1185r2.html [P1630]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1630r1.html [feature_test]: https://en.cppreference.com/w/cpp/feature_test
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@allevato this PR ties to C++20 compatibility that I've seen you have been working on recently, so I think you might be interested in having a look 🙂 |
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@swift-ci please test |
allevato
reviewed
Aug 10, 2023
include/swift/Driver/Compilation.h
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| @@ -102,8 +102,7 @@ class Compilation { | |||
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| /// Construct a \c Compilation::Result from just an exit code. | |||
| static Result code(int code) { | |||
| return Compilation::Result{false, code, | |||
| fine_grained_dependencies::ModuleDepGraph()}; | |||
| return Compilation::Result{false, code}; | |||
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It looks like the removal of the ModuleDepGraph argument here is causing a compilation failure: https://ci.swift.org/job/swift-PR-macos/10494/console
Does that behave differently under C++20?
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ah, no, this is me not testing the git merge I did 😅 I had default arguments set in the constructor before
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can you retest now?
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@swift-ci please test |
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In a downstream project we are using the Swift code as a library and compiling with C++20. This mostly works except for two backward incompatibilities introduced by C++20:
swift::Compilation::Result. The backward and forward compatible fix for that is to provide a constructor turning aggregate initializations into a normal constructor call.depGraphparameter (that ultimately holds twostd::unordered_maps) ofswift::Compilation::Result's constructor.swift::ValueOwnershipKind. The fix in this case is to remove some redundant operator definitions conditionally on the__cpp_impl_three_way_comparisonfeature test macro, which includes the papers mentioned above.