[cxx-interop] Import typedef-ed template instantiations
#32950
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Co-authored-by: Dmitri Gribenko <gribozavr@gmail.com>
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We are seeing following test failures: https://ci.swift.org/job/oss-swift-incremental-RA-osx/12557/console |
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I'm investigating, but it's getting late here in Europe, so the fix might get submitted tomorrow morning. Feel free to rollback if that's not soon enough. |
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This is the error from the log: Building on my mac in the meantime. |
| ### Class templates: Importing full class template instantiations | ||
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| A class template instantiation could be imported as a struct named | ||
| `__CxxTemplateInst` plus Itanium mangled type of the instantiation (see the |
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Instead of prefixing each declaration name, could we add another special module context like So and SC for ObjC/C synthesized declarations?
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Yes we could. The benefit would be having shorter mangled names and smaller metadata. The downside is slight increase in implementation complexity. For my use cases, I'd definitely appreciate any shortening of mangled names I can get. However, we biased towards reducing implementation complexity.
What's your preference?
) This is a roll-forward of #32950, with explicit c++17 version removed from tests. This is not needed since C++17 is the default anyway. -- In this PR we teach `ClangImporter` to import typedef statements with template instantiation as its underlying type. ```c++ template<class T> struct MagicWrapper { T t; }; struct MagicNumber {}; typedef MagicWrapper<MagicNumber> WrappedMagicNumber; ``` will be made available in Swift as if `WrappedMagicNumber` is a regular struct. In C++, multiple distinct typedeffed instantiations resolve to the same canonical type. We implement this by creating a hidden intermediate struct that typedef aliasses. The struct is named as `__CxxTemplateInst` plus Itanium mangled type of the instantiation. For the example above the name of the hidden struct is `__CxxTemplateInst12MagicWrapperI11MagicNumberE`. Double underscore (denoting a reserved C++ identifier) is used to discourage direct usage. We chose Itanium mangling scheme because it produces valid Swift identifiers and covers all C++ edge cases. Imported module interface of the example above: ```swift struct __CxxTemplateInst12MagicWrapperI11MagicNumberE { var t: MagicNumber } struct MagicNumber {} typealias WrappedMagicNumber = __CxxTemplateInst12MagicWrapperI11MagicNumberE ``` We modified the `SwiftLookupTable` logic to show hidden structs in `swift_ide_test` for convenience. Co-authored-by: Rosica Dejanovska <rosica@google.com> Co-authored-by: Dmitri Gribenko <gribozavr@gmail.com> Co-authored-by: Robert Widmann <devteam.codafi@gmail.com>
…2950. Specifically: * class template with variadic parameter * class template with non-type parameter * class template with template template parameter
In this PR we teach
ClangImporterto import typedef statements with template instantiation as its underlying type.will be made available in Swift as if
WrappedMagicNumberis a regular struct.In C++, multiple distinct typedeffed instantiations resolve to the same canonical type. We implement this by creating a hidden intermediate struct that typedef aliasses.
The struct is named as
__CxxTemplateInstplus Itanium mangled type of the instantiation. For the example above the name of the hidden struct is__CxxTemplateInst12MagicWrapperI11MagicNumberE. Double underscore (denoting a reserved C++ identifier) is used to discourage direct usage. We chose Itanium mangling scheme because it produces valid Swift identifiers and covers all C++ edge cases.Imported module interface of the example above:
We modified the
SwiftLookupTablelogic to show hidden structs inswift_ide_testfor convenience.Resolves https://bugs.swift.org/browse/SR-12591.