🌸 [6.1] Work around Foundation NS_TYPED_ENUM bug #78989
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beccadax
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🍒 release cherry pick
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@swift-ci test |
nkcsgexi
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Jan 28, 2025
Consider code like:
```
// Foo.h
typealias NSString * FooKey NS_EXTENSIBLE_TYPED_ENUM;
// Foo.swift
extension FooKey { … }
```
When Swift binds the extension to `FooKey`, that forces ClangImporter to import `FooKey`. ClangImporter’s newtype logic, among other things, checks whether the underlying type (`Swift.String` here) is Objective-C bridgeable and, if so, makes `FooKey` bridgeable too.
But what happens if this code is actually *in* Foundation, which is where the `extension String: _ObjectiveCBridgeable` lives? Well, if the compiler has already bound that extension, it works fine…but if it hasn’t, `FooKey` ends up unbridgeable, which can cause both type checking failures and IRGen crashes when code tries to use its bridging capabilities. And these symptoms are sensitive to precise details of the order Swift happens to bind extensions in, so e.g. adding empty files to the project can make the bug appear or disappear. Spooky.
Add a narrow hack to ClangImporter (only active for types in Foundation) to *assume* that `String` is bridgeable even if the extension declaring this hasn’t been bound yet.
Fixes rdar://142693093.
These would have helped us to debug rdar://142693093 more quickly.
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Cleared up conflict with #78955. |
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@swift-ci please test |
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NS_TYPED_ENUMs extended in Foundation by assuming the existence of a conformance the compiler may not have discovered yet. Without this fix, the compiler may importNS_TYPED_ENUMs without the correct bridging conformances, causing typechecking failures or compiler crashes. This change also includes compiler debugging improvements, including new PrettyStackTraces around the crash site.NS_TYPED_ENUMtypes from the Foundation module.