[Serialization] Track whether a cross-reference came from Clang #17333
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Cross-references are identified by their containing module, with the assumption that two modules will never have the same name. However, an overlay has the same name as its underlying Clang module, which means that there can be two declarations with the same name, the same type, and the same module name. This is the underlying cause of the 'UIEdgeInsetsZero' problem, but it also affects the CloudKit overlay. By tracking a bit that just says "this came from Clang", we're able to resolve otherwise ambiguous cross-references. (Why didn't we do it this way all along? Because if a declaration moves from Clang to Swift or vice versa, that would break the cross-reference. But that's only interesting if the swiftmodule format is meant to be persistent across changing dependencies, and it looks like we're moving away from that anyway. It's also a little weird for SerializedModuleLoader to have special cases for Clang, but this isn't the first.) Note that I'm not reverting the UIEdgeInsetsZero workaround here; the end state will have that coming just from UIKit as originally described. rdar://problem/40839486
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@swift-ci Please test |
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@swift-ci Please test source compatibility |
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A more general way of thinking about this is that our cross-references exist at a lower level than the source language and that therefore there are just separate namespaces of modules that we need to build cross-references to. I think that makes it more obvious that this is a reasonable design and that, if we started importing e.g. Rust modules, we would just have to generalize this bit to a tri-state or beyond. |
DougGregor
approved these changes
Jun 20, 2018
| @@ -1226,6 +1227,8 @@ static void filterValues(Type expectedTy, ModuleDecl *expectedModule, | |||
| return true; | |||
| if (value->isStatic() != isStatic) | |||
| return true; | |||
| if (value->hasClangNode() != importedFromClang) | |||
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IIRC, hasClangNode() won't be true for NS_ERROR_ENUM struct types, so you likely have the same issue with cross-references to those.
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Yeah, I was going to punt on that. I suppose this could all be a getModuleScopeContext check instead.
jrose-apple
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…e#17333) Cross-references are identified by their containing module, with the assumption that two modules will never have the same name. However, an overlay has the same name as its underlying Clang module, which means that there can be two declarations with the same name, the same type, and the same module name. This is the underlying cause of the 'UIEdgeInsetsZero' problem, but it also affects the CloudKit overlay. By tracking a bit that just says "this came from Clang", we're able to resolve otherwise ambiguous cross-references. (Why didn't we do it this way all along? Because if a declaration moves from Clang to Swift or vice versa, that would break the cross-reference. But that's only interesting if the swiftmodule format is meant to be persistent across changing dependencies, and it looks like we're moving away from that anyway. It's also a little weird for SerializedModuleLoader to have special cases for Clang, but this isn't the first.) Note that I'm not reverting the UIEdgeInsetsZero workaround here; the end state will have that coming just from UIKit as originally described. rdar://problem/40839486 (cherry picked from commit 6b89415)
jrose-apple
added a commit
to jrose-apple/swift
that referenced
this pull request
Jun 20, 2018
…e#17333) Cross-references are identified by their containing module, with the assumption that two modules will never have the same name. However, an overlay has the same name as its underlying Clang module, which means that there can be two declarations with the same name, the same type, and the same module name. This is the underlying cause of the 'UIEdgeInsetsZero' problem, but it also affects the CloudKit overlay. By tracking a bit that just says "this came from Clang", we're able to resolve otherwise ambiguous cross-references. (Why didn't we do it this way all along? Because if a declaration moves from Clang to Swift or vice versa, that would break the cross-reference. But that's only interesting if the swiftmodule format is meant to be persistent across changing dependencies, and it looks like we're moving away from that anyway. It's also a little weird for SerializedModuleLoader to have special cases for Clang, but this isn't the first.) Note that I'm not reverting the UIEdgeInsetsZero workaround here; the end state will have that coming just from UIKit as originally described. rdar://problem/40839486 (cherry picked from commit 6b89415)
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Cross-references are identified by their containing module, with the assumption that two modules will never have the same name. However, an overlay has the same name as its underlying Clang module, which means that there can be two declarations with the same name, the same type, and the same module name. This is the underlying cause of the 'UIEdgeInsetsZero' problem (#17122), but it also affects the CloudKit overlay.
By tracking a bit that just says "this came from Clang", we're able to resolve otherwise ambiguous cross-references.
(Why didn't we do it this way all along? Because if a declaration moves from Clang to Swift or vice versa, that would break the cross-reference. But that's only interesting if the swiftmodule format is meant to be persistent across changing dependencies, and it looks like we're moving away from that anyway. It's also a little weird for SerializedModuleLoader to have special cases for Clang, but this isn't the first.)
Note that I'm not reverting the UIEdgeInsetsZero workaround here; the end state will have that coming just from UIKit as originally described in #17122.
rdar://problem/40839486