Fix SIL printer issue with concrete constrained extensions #5266
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Sugared GenericTypeParamTypes point to GenericTypeParamDecls, allowing the name of the parameter as written by the user to be recovered. Canonical GenericTypeParamTypes on the other hand only store a depth and index, without referencing the original declaration. When printing SIL, we wish to output the original generic parameter names, even though SIL only uses canonical types. Previously, we used to accomplish this by mapping the generic parameter to an archetype and printing the name of the archetype. This was not adequate if multiple generic parameters mapped to the same archetype, or if a generic parameter was mapped to a concrete type. The new approach preserves the original sugared types in the GenericEnvironment, adding a new GenericEnvironment::getSugaredType() method. There are also some other assorted simplifications made possible by this. Unfortunately this makes GenericEnvironments use a bit more memory, however I have more improvements coming that will offset the gains, in addition to making substitution lists smaller also.
Previous refactorings introducing GenericEnvironment left behind some lint.
Now that we have the ability to write extensions where one of the type parameters is equivalent to a concrete type, eliminate _AnyHashableProtocol and provide AnyHashable-specific behavior for Dictionary (where Key == AnyHashable) and Set (where Element == AnyHashable) rather than employing the "Key: _AnyHashableProtocol" hack. Fixes standard library ABI FIXME's swiftlang#35, swiftlang#37, swiftlang#39.
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@swift-ci Please smoke test |
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Awesome! -3 ABI FIXMEs. I suggest that you add a ChangeLong entry for this highly-requested feature. |
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@DougGregor I added a changelog entry with the original PR, before the follow-up bug fixes. |
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SIL uses canonical types, but we still want to print them as if they were sugared, using the original generic parameter name instead of τ_M_N. Previously we would print the name of the archetype, which was wrong if a generic parameter was mapped to a concrete type, or if multiple generic parameters mapped to the same archetype. Re-work the AST printer and SIL serialization to preserve the sugar on the
GenericTypeParamTypeproperly.This allows @DougGregor's ABI fix to be re-applied.
This is the last remaining issue before we can close rdar://problem/17821143 (that I'm aware of).