[Explicit Module Builds] Use a stable hash to encode build arguments into PCM filenames #358
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@swift-ci please test |
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😬 Linux build failing with: |
owenv
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Nov 13, 2020
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| if #available(macOS 10.15, iOS 13, *) { | ||
| hashedArguments = CryptoKitSHA256().hash(hashInput).hexadecimalRepresentation |
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It looks like this is failing on Linux because the true branch of the #available condition is taken. I'm not sure if there's a better way to write this than something like:
#if os(macOS)
if #available(macOS 10.15, iOS 13, *) {
hashedArguments = CryptoKitSHA256().hash(hashInput).hexadecimalRepresentation
} else {
hashedArguments = SHA256().hash(hashInput).hexadecimalRepresentation
}
#else
hashedArguments = SHA256().hash(hashInput).hexadecimalRepresentation
#endif
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Right, the wildcard...
I can't think of a better way either.
Thanks, @owenv.
…into PCM filenames When generating build jobs for explicit module dependencies, we must distinguish multiple versions of the same Clang module/pcm by encoding the arguments used to build it (e.g. target triple) into the pcm filename. So far, we have been using an unstable hash, which means that these filenames were not stable across invocations and were being needlessly re-built in some scenarios (e.g. many-target builds). Switching to a stable hash (SHA256 in this instance) ensures that the same Clang module, built with the same command line, will produce the same .pcm filename. This will allow the client build system (such as SwiftPM) to deduplicate identical compilation jobs because their output filenames will now also match.
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@swift-ci please test |
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owenv
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Nov 14, 2020
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When generating build jobs for explicit module dependencies, we must distinguish multiple versions of the same Clang module/pcm by encoding the arguments used to build it (e.g. target triple) into the pcm filename.
So far, we have been using an unstable hash, which means that these filenames were not stable across invocations and were being needlessly re-built in some scenarios (e.g. many-target builds).
Switching to a stable hash (SHA256) ensures that the same Clang module, built with the same command line, will produce the same .pcm filename. This will allow the client build system (e.g. SwiftPM) to deduplicate identical compilation jobs because their output filenames will now also match.