[ASTMangler] Mangle nested imported error structs correctly #24804
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Error structs synthesized by ClangImporter can be renamed using SWIFT_NAME() to syntactically appear anywhere in the type hierarchy with any name, but they should always be mangled as `__C_Synthesized.related decl ‘e’ of <Objective-C enum name>`. Unforunately, when SWIFT_NAME() was used to nest the error struct inside another type, an ASTMangler bug would cause it to be mangled as `<parent type>.related decl ‘e’ of <Objective-C enum name>`, and an ASTDemangler bug would also require a valid parent type. This created a mismatch between the compiler’s and runtime’s manglings which caused crashes when you tried to match the imported error struct in a `catch`. This PR corrects the compiler bugs so that it generates the mangling the runtime expects. This is theoretically ABI-breaking, but as far as I can determine nobody has shipped the incorrectly mangled names, presumably because they crash when you try to use them. Fixes <rdar://problem/48040880>.
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@swift-ci please test |
slavapestov
approved these changes
May 15, 2019
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Error structs synthesized by ClangImporter can be renamed using
SWIFT_NAME()to syntactically appear anywhere in the type hierarchy with any name, but they should always be mangled as__C_Synthesized.related decl ‘e’ of <clang enum name>. Unfortunately, whenSWIFT_NAME()was used to nest the error struct inside another type, an ASTMangler bug would cause it to be mangled as<parent type>.related decl ‘e’ of <clang enum name>, and an ASTDemangler bug would also require a valid parent type. This created a mismatch between the compiler’s and runtime’s manglings which caused crashes when you tried to match the imported error struct in acatch.This PR corrects the compiler bugs so that it generates the mangling the runtime expects. This is theoretically ABI-breaking, but as far as I can determine nobody has shipped the incorrectly mangled names, presumably because they crash when you try to use them.
Fixes rdar://problem/48040880.
(This PR does not affect the mangling of error types written in Swift, only ones imported from Clang.)