swift234

[swiftc] Add test case for crash triggered in swift::TypeChecker::checkGenericParamList(swift::ArchetypeBuilder*, swift::GenericParamList*, swift::GenericSignature*, bool, swift::GenericTypeResolver*)

Stack trace:

```
4  swift           0x0000000000ed76dd swift::TypeChecker::checkGenericParamList(swift::ArchetypeBuilder*, swift::GenericParamList*, swift::GenericSignature*, bool, swift::GenericTypeResolver*) + 93
5  swift           0x0000000000ed8ef7 swift::TypeChecker::validateGenericSignature(swift::GenericParamList*, swift::DeclContext*, swift::GenericSignature*, std::function<bool (swift::ArchetypeBuilder&)>, bool&) + 135
6  swift           0x0000000000ed9296 swift::TypeChecker::validateGenericTypeSignature(swift::GenericTypeDecl*) + 102
7  swift           0x0000000000e9b20f swift::TypeChecker::validateDecl(swift::ValueDecl*, bool) + 1583
11 swift           0x0000000000f0b99e swift::TypeChecker::resolveIdentifierType(swift::DeclContext*, swift::IdentTypeRepr*, swift::OptionSet<swift::TypeResolutionFlags, unsigned int>, bool, swift::GenericTypeResolver*, llvm::function_ref<bool (swift::TypeCheckRequest)>*) + 158
13 swift           0x0000000000f0c9a4 swift::TypeChecker::resolveType(swift::TypeRepr*, swift::DeclContext*, swift::OptionSet<swift::TypeResolutionFlags, unsigned int>, swift::GenericTypeResolver*, llvm::function_ref<bool (swift::TypeCheckRequest)>*) + 164
14 swift           0x0000000000f0b890 swift::TypeChecker::validateType(swift::TypeLoc&, swift::DeclContext*, swift::OptionSet<swift::TypeResolutionFlags, unsigned int>, swift::GenericTypeResolver*, llvm::function_ref<bool (swift::TypeCheckRequest)>*) + 192
15 swift           0x0000000000eded47 swift::TypeChecker::typeCheckPattern(swift::Pattern*, swift::DeclContext*, swift::OptionSet<swift::TypeResolutionFlags, unsigned int>, swift::GenericTypeResolver*) + 967
17 swift           0x0000000000e9bc19 swift::TypeChecker::validateDecl(swift::ValueDecl*, bool) + 4153
18 swift           0x0000000000f1d49d swift::createImplicitConstructor(swift::TypeChecker&, swift::NominalTypeDecl*, swift::ImplicitConstructorKind) + 413
19 swift           0x0000000000ea6176 swift::TypeChecker::addImplicitConstructors(swift::NominalTypeDecl*) + 1526
22 swift           0x0000000000ea0566 swift::TypeChecker::typeCheckDecl(swift::Decl*, bool) + 150
25 swift           0x0000000000f060c4 swift::TypeChecker::typeCheckClosureBody(swift::ClosureExpr*) + 244
26 swift           0x0000000000f3094c swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::Expr*, swift::Type, bool, bool, bool) + 876
27 swift           0x0000000000e8e211 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*) + 769
29 swift           0x0000000000f06206 swift::TypeChecker::typeCheckTopLevelCodeDecl(swift::TopLevelCodeDecl*) + 134
30 swift           0x0000000000ec387d swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int) + 1101
31 swift           0x0000000000c585e9 swift::CompilerInstance::performSema() + 3289
33 swift           0x00000000007d6f4f swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 2863
34 swift           0x00000000007a2f58 main + 2872
Stack dump:
0.	Program arguments: /path/to/swift/bin/swift -frontend -c -primary-file validation-test/compiler_crashers/28303-swift-typechecker-checkgenericparamlist.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -module-name main -o /tmp/28303-swift-typechecker-checkgenericparamlist-4befae.o
1.	While type-checking expression at [validation-test/compiler_crashers/28303-swift-typechecker-checkgenericparamlist.swift:9:1 - line:9:41] RangeText="{struct T{let t:e}typealias e:T where h:a"
2.	While type-checking 'T' at validation-test/compiler_crashers/28303-swift-typechecker-checkgenericparamlist.swift:9:2
3.	While resolving type e at [validation-test/compiler_crashers/28303-swift-typechecker-checkgenericparamlist.swift:9:17 - line:9:17] RangeText="e"
<unknown>:0: error: unable to execute command: Segmentation fault
<unknown>:0: error: compile command failed due to signal (use -v to see invocation)
```