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Merge pull request #3047 from antlr/fix-swift-crasher 

work around Swift crash where reading hashValue on SemanticContext.AND
(merged by @ericvergnaud  since @ewanmellor is not able to look into it)
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ericvergnaud 2021-01-24 15:04:46 +08:00 committed by GitHub
parent b050ac43de 020333deff
commit 8227df1c1e
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1 changed files with 21 additions and 7 deletions
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28
runtime/Swift/Sources/Antlr4/atn/LookupDictionary.swift
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@ -28,13 +28,27 @@ public struct LookupDictionary {
private func hash(_ config: ATNConfig) -> Int {
if type == LookupDictionaryType.lookup {
var hashCode: Int = 7
hashCode = 31 * hashCode + config.state.stateNumber
hashCode = 31 * hashCode + config.alt
hashCode = 31 * hashCode + config.semanticContext.hashValue
return hashCode
/* migrating to XCode 12.3/Swift 5.3 introduced a very weird bug
where reading hashValue from a SemanticContext.AND instance woul:
call the AND empty constructor
NOT call AND.hash(into)
Could it be a Swift compiler bug ?
All tests pass when using Hasher.combine()
Keeping the old code for reference:
var hashCode: Int = 7
hashCode = 31 * hashCode + config.state.stateNumber
hashCode = 31 * hashCode + config.alt
hashCode = 31 * hashCode + config.semanticContext.hashValue // <- the crash would occur here
return hashCode
*/
var hasher = Hasher()
hasher.combine(7)
hasher.combine(config.state.stateNumber)
hasher.combine(config.alt)
hasher.combine(config.semanticContext)
return hasher.finalize()
} else {
//Ordered
return config.hashValue