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Circular reference and compiler crash on memberAttribute macro expansion #78154

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Circular reference and compiler crash on memberAttribute macro expansion#78154
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bugA deviation from expected or documented behavior. Also: expected but undesirable behavior.crashBug: A crash, i.e., an abnormal termination of softwaretriage neededThis issue needs more specific labels
@li3zhen1

Description

@li3zhen1
li3zhen1
opened on Dec 13, 2024

Description

No response

Reproduction

public protocol G {
    associatedtype T: Hashable // Doesn't crash if T has no constraints

    init(t: [T])
}

@Noop             // A member Attribute macro that return an empty list of syntax node.
extension G {
    public static var empty: Self {
        .init(t: [])
    }
}

Macro:

public struct NoopMacro: MemberAttributeMacro {
    public static func expansion(
        of node: SwiftSyntax.AttributeSyntax,
        attachedTo declaration: some SwiftSyntax.DeclGroupSyntax,
        providingAttributesFor member: some SwiftSyntax.DeclSyntaxProtocol,
        in context: some SwiftSyntaxMacros.MacroExpansionContext
    ) throws -> [SwiftSyntax.AttributeSyntax] {
        return []
    }
}
@attached(memberAttribute)
public macro Noop() = #externalMacro(module: "...", type: "NoopMacro")

Stack dump

144 | 
145 | 
146 | public protocol G {
    |                 |- error: circular reference
    |                 |- note: through reference here
    |                 |- note: through reference here
    |                 |- note: through reference here
    |                 `- note: through reference here
147 |     associatedtype T: Hashable
    |                       |- note: while resolving type 'Hashable'
    |                       `- note: through reference here
148 | 
149 |     init(t: [T])
    :
151 | 
152 | @Noop
153 | extension G {
    | `- note: through reference here
154 |     public static var empty: Self {
    |                       `- note: circular reference expanding member attribute macros on 'empty'
155 |         .init(t: [])
156 |     }

/Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/CompactGraph.swift:146:17: error: circular reference
144 | 
145 | 
146 | public protocol G {
    |                 |- error: circular reference
    |                 |- note: through reference here
    |                 |- note: through reference here
    |                 |- note: through reference here
    |                 |- note: through reference here
    |                 `- note: through reference here
147 |     associatedtype T: Hashable
    |                       |- note: while resolving type 'Hashable'
    |                       `- note: through reference here
148 | 
149 |     init(t: [T])
    :
151 | 
152 | @Noop
153 | extension G {
    | `- note: through reference here
154 |     public static var empty: Self {
    |                       `- note: circular reference expanding member attribute macros on 'empty'
155 |         .init(t: [])
156 |     }

Redundant conformance requirements in signature <Self where Self : G>:
Ours:
- Copyable
- Escapable
- Hashable
Theirs:
- Hashable
All requirements:
(requirement "Self" conforms_to "Copyable")
(requirement "Self" conforms_to "Escapable")
(requirement "Self.[G]T" conforms_to "Copyable")
(requirement "Self.[G]T" conforms_to "Escapable")
(requirement "Self.[G]T" conforms_to "Hashable")
Requirement machine for <τ_0_0 where τ_0_0 : G>
Rewrite system: {
- [G].[G] => [G] [permanent]
- [G].T => [G:T] [permanent]
- [G].[Copyable] => [G] [explicit]
- [G].[Escapable] => [G] [explicit]
- [G:T].[Copyable] => [G:T] [explicit]
- [G:T].[Escapable] => [G:T] [explicit]
- [G].[G:T] => [G:T]
- τ_0_0.[G] => τ_0_0 [explicit]
- τ_0_0.T => τ_0_0.[G:T]
- τ_0_0.[Copyable] => τ_0_0
- τ_0_0.[Escapable] => τ_0_0
}
Property map: {
  [G] => { conforms_to: [G Copyable Escapable] }
  [G:T] => { conforms_to: [Copyable Escapable] }
  τ_0_0 => { conforms_to: [G Copyable Escapable] }
}
Conformance paths: {
}
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.
Stack dump:
0.      Program arguments: /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/bin/swift-frontend -frontend -emit-module -experimental-skip-non-inlinable-function-bodies-without-types /Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/Algorithms/DepthFirstSearch.swift /Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/Algorithms/GreedyFAS.swift /Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/CompactGraph.swift /Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/CompactGraphProtocol.swift -target arm64-apple-macosx15.0 -Xllvm -aarch64-use-tbi -enable-objc-interop -sdk /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk -I /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/Modules -I /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/lib/swift/macosx/testing -I /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/lib -F /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/Library/Frameworks -color-diagnostics -enable-testing -g -debug-info-format=dwarf -dwarf-version=5 -module-cache-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/ModuleCache -swift-version 6 -Onone -D SWIFT_PACKAGE -D DEBUG -load-plugin-executable /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/MakeEverythingInlinableMacros-tool#MakeEverythingInlinableMacros -empty-abi-descriptor -plugin-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/lib/swift/host/plugins/testing -resource-dir /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/lib/swift -enable-anonymous-context-mangled-names -file-compilation-dir /Users/lizhen/Projects/GraphEssentials -Xcc -fmodule-map-file=/Users/lizhen/Projects/GraphEssentials/.build/checkouts/swift-syntax/Sources/_SwiftSyntaxCShims/include/module.modulemap -Xcc -I -Xcc /Users/lizhen/Projects/GraphEssentials/.build/checkouts/swift-syntax/Sources/_SwiftSyntaxCShims/include -Xcc -isysroot -Xcc /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk -Xcc -F -Xcc /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/Library/Frameworks -Xcc -fPIC -Xcc -g -module-name GraphEssentials -package-name graphessentials -in-process-plugin-server-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/lib/swift/host/libSwiftInProcPluginServer.dylib -plugin-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Library/Developer/Toolchains/swift-DEVELOPMENT-SNAPSHOT-2024-11-09-a.xctoolchain/usr/local/lib/swift/host/plugins -target-sdk-version 15.2 -target-sdk-name macosx15.2 -external-plugin-path /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/lib/swift/host/plugins#/Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server -external-plugin-path /Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/local/lib/swift/host/plugins#/Users/lizhen/Downloads/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server -emit-module-doc-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/Modules/GraphEssentials.swiftdoc -emit-module-source-info-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/Modules/GraphEssentials.swiftsourceinfo -emit-objc-header-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/GraphEssentials.build/GraphEssentials-Swift.h -emit-dependencies-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/GraphEssentials.build/GraphEssentials.emit-module.d -parse-as-library -o /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/Modules/GraphEssentials.swiftmodule -emit-abi-descriptor-path /Users/lizhen/Projects/GraphEssentials/.build/arm64-apple-macosx/debug/Modules/GraphEssentials.abi.json
1.      Apple Swift version 6.1-dev (LLVM 5c0d283c37132bf, Swift b5af518638c9a16)
2.      Compiling with the current language version
3.      While evaluating request TypeCheckSourceFileRequest(source_file "/Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/CompactGraph.swift")
4.      While type-checking 'G' (at /Users/lizhen/Projects/GraphEssentials/Sources/GraphEssentials/CompactGraph.swift:146:8)
5.      While checking generic signature <τ_0_0 where τ_0_0 : G>
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  swift-frontend           0x0000000106c3f0f8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000106c3d7dc llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x0000000106c3f754 SignalHandler(int) + 304
3  libsystem_platform.dylib 0x000000018fc5ae04 _sigtramp + 56
4  libsystem_pthread.dylib  0x000000018fc23f70 pthread_kill + 288
5  libsystem_c.dylib        0x000000018fb30908 abort + 128
6  swift-frontend           0x0000000102996c58 swift::GenericSignature::verify(llvm::ArrayRef<swift::Requirement>) const::$_7::operator()() const + 152
7  swift-frontend           0x0000000102996104 swift::GenericSignature::verify(llvm::ArrayRef<swift::Requirement>) const + 2600
8  swift-frontend           0x00000001024b6850 (anonymous namespace)::DeclChecker::visit(swift::Decl*) + 8848
9  swift-frontend           0x00000001024b45ac swift::TypeChecker::typeCheckDecl(swift::Decl*) + 136
10 swift-frontend           0x00000001025942c8 swift::TypeCheckSourceFileRequest::evaluate(swift::Evaluator&, swift::SourceFile*) const + 164
11 swift-frontend           0x0000000102595e84 swift::TypeCheckSourceFileRequest::OutputType swift::Evaluator::getResultUncached<swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()>(swift::TypeCheckSourceFileRequest const&, swift::TypeCheckSourceFileRequest::OutputType swift::evaluateOrDefault<swift::TypeCheckSourceFileRequest>(swift::Evaluator&, swift::TypeCheckSourceFileRequest, swift::TypeCheckSourceFileRequest::OutputType)::'lambda'()) + 232
12 swift-frontend           0x00000001025941fc swift::performTypeChecking(swift::SourceFile&) + 84
13 swift-frontend           0x000000010139e980 bool llvm::function_ref<bool (swift::SourceFile&)>::callback_fn<swift::CompilerInstance::performSema()::$_8>(long, swift::SourceFile&) + 16
14 swift-frontend           0x00000001013979f4 swift::CompilerInstance::forEachFileToTypeCheck(llvm::function_ref<bool (swift::SourceFile&)>) + 156
15 swift-frontend           0x0000000101397938 swift::CompilerInstance::performSema() + 76
16 swift-frontend           0x0000000101150f58 withSemanticAnalysis(swift::CompilerInstance&, swift::FrontendObserver*, llvm::function_ref<bool (swift::CompilerInstance&)>, bool) + 60
17 swift-frontend           0x000000010114693c performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 716
18 swift-frontend           0x0000000101146008 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2328
19 swift-frontend           0x0000000100f1d540 swift::mainEntry(int, char const**) + 3100
20 dyld                     0x000000018f8a4274 start + 2840

Expected behavior

Compiles.

Environment

Apple Swift version 6.1-dev (LLVM 5c0d283c37132bf, Swift b5af518)
Target: arm64-apple-macosx15.0

Additional information

The same crash happens if @Noop is replaced with @Observable from Observation.

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    bugA deviation from expected or documented behavior. Also: expected but undesirable behavior.crashBug: A crash, i.e., an abnormal termination of softwaretriage neededThis issue needs more specific labels

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