generic pack iteration compiler crash when accessing property

[lukaskollmer]

Description

Not sure how to describe this exactly, but basically if you try to access, in a pack iteration, a property of a generic type, which is itself a property of a generic type, the compiler crashes.

The program below is a simplified version of a program where I encountered this issue; i'm not sure if there's just one bug here or multiple, since there seem to be multilpe constellations of changes one can apply to the program to get it to work/crash.

For example, in the program below, any of the following changes will make it compile

• make SampleType non-generic
• add a property of type T to SampleType
• remove either the title: String or the range: ClosedRange<Double>? property
• make the range property non-optional
• change the type of range to e.g. Int

Reproduction

struct SampleType<T> {
    let title: String
    let range: ClosedRange<Double>?
}


protocol Results {
    associatedtype Sample
    var sampleType: SampleType<Sample> { get }
}


final class Entry<R: Results> {
    let results: R
    
    init(results: R) {
        self.results = results
    }
}


struct View<each R: Results> {
    let entry: (repeat Entry<each R>)
    
    var broken: Void {
        for entry in repeat each entry {
            _ = entry.results.sampleType
        }
    }
    
    var fine: Void {
        func imp<T>(_ entry: Entry<T>) {
            _ = entry.results.sampleType
        }
        repeat imp(each entry)
    }
}

Stack dump

1.	Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
2.	Compiling with the current language version
3.	While evaluating request IRGenRequest(IR Generation for file "/Users/lukas/Developer/test/test_2024-12-29b/test_2024-12-29b/main.swift")
4.	While emitting IR SIL function "@$s16test_2024_12_29b4ViewV6brokenytvg".
 for getter for broken (at /Users/lukas/Developer/test/test_2024-12-29b/test_2024-12-29b/main.swift:42:9)
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           0x0000000106426a9c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1  swift-frontend           0x0000000106424cf0 llvm::sys::RunSignalHandlers() + 112
2  swift-frontend           0x0000000106427068 SignalHandler(int) + 292
3  libsystem_platform.dylib 0x000000019179a584 _sigtramp + 56
4  swift-frontend           0x00000001014a9924 swift::irgen::getTypeAndGenericSignatureForManglingOutlineFunction(swift::SILType) + 344
5  swift-frontend           0x00000001014abc44 swift::irgen::OutliningMetadataCollector::emitCallToOutlinedRelease(swift::irgen::Address, swift::SILType, swift::irgen::TypeInfo const&, swift::irgen::Atomicity) const + 352
6  swift-frontend           0x00000001014aba40 swift::irgen::TypeInfo::callOutlinedRelease(swift::irgen::IRGenFunction&, swift::irgen::Address, swift::SILType, swift::irgen::Atomicity) const + 120
7  swift-frontend           0x0000000101421a88 (anonymous namespace)::IRGenSILFunction::visitSILBasicBlock(swift::SILBasicBlock*) + 75976
8  swift-frontend           0x000000010140dea4 (anonymous namespace)::IRGenSILFunction::emitSILFunction() + 13220
9  swift-frontend           0x000000010140a65c swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 2088
10 swift-frontend           0x0000000101255834 swift::irgen::IRGenerator::emitGlobalTopLevel(std::__1::vector<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, std::__1::allocator<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>> const&) + 3364
11 swift-frontend           0x00000001013c15a8 swift::IRGenRequest::evaluate(swift::Evaluator&, swift::IRGenDescriptor) const + 4700
12 swift-frontend           0x0000000101409ba8 swift::SimpleRequest<swift::IRGenRequest, swift::GeneratedModule (swift::IRGenDescriptor), (swift::RequestFlags)9>::evaluateRequest(swift::IRGenRequest const&, swift::Evaluator&) + 176
13 swift-frontend           0x00000001013ca394 swift::IRGenRequest::OutputType swift::Evaluator::getResultUncached<swift::IRGenRequest, swift::IRGenRequest::OutputType swift::evaluateOrFatal<swift::IRGenRequest>(swift::Evaluator&, swift::IRGenRequest)::'lambda'()>(swift::IRGenRequest const&, swift::IRGenRequest::OutputType swift::evaluateOrFatal<swift::IRGenRequest>(swift::Evaluator&, swift::IRGenRequest)::'lambda'()) + 784
14 swift-frontend           0x00000001013c3e90 swift::performIRGeneration(swift::FileUnit*, swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::GlobalVariable**) + 180
15 swift-frontend           0x0000000100dd34bc generateIR(swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, llvm::GlobalVariable*&, llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>>) + 156
16 swift-frontend           0x0000000100dcece4 performCompileStepsPostSILGen(swift::CompilerInstance&, std::__1::unique_ptr<swift::SILModule, std::__1::default_delete<swift::SILModule>>, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, swift::PrimarySpecificPaths const&, int&, swift::FrontendObserver*) + 2176
17 swift-frontend           0x0000000100dcdbd0 swift::performCompileStepsPostSema(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 984
18 swift-frontend           0x0000000100dd0e88 performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 1684
19 swift-frontend           0x0000000100dcfbb4 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3572
20 swift-frontend           0x0000000100d56a5c swift::mainEntry(int, char const**) + 3680
21 dyld                     0x00000001913df154 start + 2476

Expected behavior

the code, as above, should compile fine when using pack iteration

Environment

swift-driver version: 1.115.1 Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Target: arm64-apple-macosx14.0

Additional information

The slightly-less-simplified version where I encountered this bug, which does in fact use the `T` generic parameter in the `SampleType` struct:

class IdentifierBase {}

protocol IdentifierTypeProviding {
    associatedtype Identifier: IdentifierBase
}


struct SampleType<T: IdentifierTypeProviding> {
    let id: T.Identifier
    let title: String
    let range: ClosedRange<Double>?
}


protocol Results {
    associatedtype Sample: IdentifierTypeProviding
    var sampleType: SampleType<Sample> { get }
}


final class Entry<R: Results> {
    let results: R
    
    init(results: R) {
        self.results = results
    }
}


struct View<each R: Results> {
    let entry: (repeat Entry<each R>)
    
    var broken: Void {
        for entry in repeat each entry {
            _ = entry.results.sampleType
        }
    }
    
    var fine: Void {
        func imp<T>(_ entry: Entry<T>) {
            _ = entry.results.sampleType
        }
        repeat imp(each entry)
    }
}