[4.2] Don't mangle generic type aliases at all #17576
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This reverts commit 410940c. Generic typealias mangling is incomplete, causing demangling and remangling failures on a number of projects. Disable it for now.
Mangling of generic typealiases for debug info is causing a long tail of bugs. Disable it on the Swift 4.2 branch; we'll fall back to the underlying type. Fixes rdar://problem/41444286.
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@swift-ci please test |
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@swift-ci please test source compatibility |
dcci
approved these changes
Jun 27, 2018
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@swift-ci please nominate |
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Build failed |
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apple/swift-lldb#724 loosens the LLDB test that was checking for a generic typealias demangling. |
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@swift-ci please test macOS |
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Build failed |
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"Jenkins error". ARGH! |
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@swift-ci please test macOS |
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@swift-ci please test macOS |
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Explanation: The recently-introduced mangling for generic typealiases produced both incorrect manglings as well as correct manglings that both the demangler and remangler would break on. Remove this functionality, which effectively reverts the behavior back to what was in Swift <= 4.1.
Scope: Affects debug builds of effectively any Swift project, because only debug builds include mangling of typealiases. A number of these were triggering compiler assertions (when the compiler was built with assertions).
Risk: Very low; we're effectively reverting back to a non-typealias mangling, which puts the debug-info path on the same code path as the rest of the compiler.
Testing: Compiler regression tests, built various other projects that were
Reviewer: @dcci
SR / Radar: rdar://problem/41444286