swift234

[swiftc] Add test case for crash triggered in swift::ArchetypeBuilder::addSuperclassRequirement(swift::ArchetypeBuilder::PotentialArchetype*, swift::Type, swift::RequirementSource)

Stack trace:

```
swift: /path/to/swift/lib/AST/Module.cpp:922: Optional<swift::ProtocolConformanceRef> swift::ModuleDecl::lookupConformance(swift::Type, swift::ProtocolDecl *, swift::LazyResolver *): Assertion `inheritedConformance && "We already found the inherited conformance"' failed.
11 swift           0x0000000000fd0afc swift::ArchetypeBuilder::addSuperclassRequirement(swift::ArchetypeBuilder::PotentialArchetype*, swift::Type, swift::RequirementSource) + 188
14 swift           0x0000000000fd260f swift::ArchetypeBuilder::visitInherited(llvm::ArrayRef<swift::TypeLoc>, llvm::function_ref<bool (swift::Type, swift::SourceLoc)>) + 175
15 swift           0x0000000000fd062a swift::ArchetypeBuilder::addAbstractTypeParamRequirements(swift::AbstractTypeParamDecl*, swift::ArchetypeBuilder::PotentialArchetype*, swift::RequirementSource::Kind, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 426
16 swift           0x0000000000fd09b7 swift::ArchetypeBuilder::addConformanceRequirement(swift::ArchetypeBuilder::PotentialArchetype*, swift::ProtocolDecl*, swift::RequirementSource, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 471
19 swift           0x0000000000fd260f swift::ArchetypeBuilder::visitInherited(llvm::ArrayRef<swift::TypeLoc>, llvm::function_ref<bool (swift::Type, swift::SourceLoc)>) + 175
20 swift           0x0000000000fd062a swift::ArchetypeBuilder::addAbstractTypeParamRequirements(swift::AbstractTypeParamDecl*, swift::ArchetypeBuilder::PotentialArchetype*, swift::RequirementSource::Kind, llvm::SmallPtrSetImpl<swift::ProtocolDecl*>&) + 426
21 swift           0x0000000000fd0455 swift::ArchetypeBuilder::addGenericParameterRequirements(swift::GenericTypeParamDecl*) + 165
22 swift           0x0000000000ed4b17 swift::TypeChecker::checkGenericParamList(swift::ArchetypeBuilder*, swift::GenericParamList*, swift::GenericSignature*, bool, swift::GenericTypeResolver*) + 375
23 swift           0x0000000000ed6217 swift::TypeChecker::validateGenericSignature(swift::GenericParamList*, swift::DeclContext*, swift::GenericSignature*, std::function<bool (swift::ArchetypeBuilder&)>, bool&) + 135
24 swift           0x0000000000ed65b6 swift::TypeChecker::validateGenericTypeSignature(swift::GenericTypeDecl*) + 102
25 swift           0x0000000000e99e1e swift::TypeChecker::validateDecl(swift::ValueDecl*, bool) + 1630
30 swift           0x0000000000e9edc6 swift::TypeChecker::typeCheckDecl(swift::Decl*, bool) + 150
33 swift           0x0000000000f0217a swift::TypeChecker::typeCheckFunctionBodyUntil(swift::FuncDecl*, swift::SourceLoc) + 346
34 swift           0x0000000000f01fde swift::TypeChecker::typeCheckAbstractFunctionBodyUntil(swift::AbstractFunctionDecl*, swift::SourceLoc) + 46
35 swift           0x0000000000f02ba3 swift::TypeChecker::typeCheckAbstractFunctionBody(swift::AbstractFunctionDecl*) + 179
37 swift           0x0000000000ec0c31 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int) + 1249
38 swift           0x0000000000c57d19 swift::CompilerInstance::performSema() + 3289
40 swift           0x00000000007d6a5f swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2863
41 swift           0x00000000007a2aa8 main + 2872
Stack dump:
0.	Program arguments: /path/to/swift/bin/swift -frontend -c -primary-file validation-test/compiler_crashers/28294-swift-archetypebuilder-addsuperclassrequirement.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/28294-swift-archetypebuilder-addsuperclassrequirement-c14518.o
1.	While type-checking 'a' at validation-test/compiler_crashers/28294-swift-archetypebuilder-addsuperclassrequirement.swift:10:1
2.	While type-checking 'B' at validation-test/compiler_crashers/28294-swift-archetypebuilder-addsuperclassrequirement.swift:11:1
<unknown>:0: error: unable to execute command: Aborted
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)
```