Fix Swift 6.2 library evolution build failures caused by @inlinable initializer restrictions - #122
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JHeisecke wants to merge 4 commits into
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Fix Swift 6.2 library evolution build failures caused by @inlinable initializer restrictions#122JHeisecke wants to merge 4 commits into
JHeisecke wants to merge 4 commits into
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Swift 6.2 with SWIFT_ENABLE_LIBRARY_EVOLUTION=YES rejects @inlinable
designated initializers that directly assign stored properties
(self.foo = ...). The compiler cannot guarantee binary compatibility
if stored property layout changes after clients have inlined the body.
Fix: remove @inlinable from all affected designated initializers
across
11 files. Inits called from @inlinable functions are annotated
@usableFromInline instead of being left internal (which would cause a
separate "cannot be referenced from @inlinable function" error).
Affected types:
- ASN1.ParserNode, ASN1.ParseResult (→ @usableFromInline)
- ASN1Node, ASN1NodeCollection, ASN1NodeCollection.Iterator (→
@usableFromInline)
- ASN1.LazySetOfSequence.Iterator (→ @usableFromInline)
- ASN1Identifier (shortIdentifier init → @usableFromInline;
tagWithNumber → public only)
- IntegerBytesCollection.Index (→ @usableFromInline)
- DER.Serializer, ASN1OctetString, ASN1BitString, ObjectIdentifier,
ASN1Any, UTCTime, GeneralizedTime, all ASN1String variants
(→ public, no inlining attribute)
…nd LazySetOfSequence
Lukasa
requested changes
May 11, 2026
Lukasa
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Lukasa
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Thanks for this patch!
SwiftASN1 does not support BUILD_LIBRARY_FOR_DISTRIBUTION. Specifically, we do not provide a stable ABI, and at this time have no intention of doing so. To that end we do not recommend using SwiftASN1 in this way.
We would be willing to accept a patch that fixes the build in that environment, but we would not be willing to do so at the cost of performance without that flag. This change removes some @inlinable flags, which will harm the performance of the stack. If you can provide a version of this patch that meets your use-case and doesn't regress your stack, I'll happily accept it.
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Motivation:
Swift 6.2 enforces stricter definite initialization rules for
@inlinableinitializers under library evolution mode (BUILD_LIBRARY_FOR_DISTRIBUTION=YES). Two distinct violations occur acrossswift-asn1:@inlinablebecause the definite initialization proof cannot be verified across module boundaries withoutself = .init(...)syntax.ASN1Null.init(derEncoded:withIdentifier:)) returns normally after validation but never explicitly sets self, which Swift 6.2 now flags as an error.This prevents
swift-asn1from compiling as a distributed binary framework (XCFramework or any library evolution target) under Swift 6.2.Modifications:
@inlinable →
@usableFromInline(or removed) on designated initializers acrossASN1.swift,ASN1BitString.swift,ASN1Identifier.swift,ASN1Integer.swift,ASN1OctetString.swift,ASN1Strings.swift,GeneralizedTime.swift,ObjectIdentifier.swift,UTCTime.swift, andDER.swift; these inits assign storedproperties directly and cannot satisfy @inlinable definite initialization requirements.
ASN1Null.init(derEncoded:withIdentifier:), addedself = .init()at end of success path, keeping the init@inlinable.ASN1Any, extracted a@usableFromInlinedesignatedinit(_serializedBytes:), then converted the two throwing@inlinablepublic inits to delegate viaself.init(_serializedBytes:...)instead of assigning the stored property directly. Removed@inlinablefrominit(derEncoded:)(non-throwing, directly assigns a computed property).Result:
swift-asn1compiles cleanly under Swift 6.2 with library evolution enabled. No behavior change, all public APIs remain callable from inlinable client code via @usableFromInline internal inits.