Open Radar

 
Summary:
Constraints on type extensions crash the compiler if they reference typealiases introduced by conformance to a protocol.


Steps to Reproduce:
1. This code:
protocol P {
	typealias T
	init(T)
}

struct S<Q>: P {
	init(Q)
}
extension S where T : Equatable {}


Expected Results:
should not crash the compiler


Actual Results:
but totally does:
Assertion failed: (!pa->getUnresolvedReferences().empty() && "Missing unresolved references?"), function operator(), file /Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-700.0.42.3/src/swift/lib/AST/ArchetypeBuilder.cpp, line 1253.
0  swift                    0x0000000102dafb9b llvm::sys::PrintStackTrace(__sFILE*) + 43
1  swift                    0x0000000102db02db SignalHandler(int) + 379
2  libsystem_platform.dylib 0x00007fff8a9b5f1a _sigtramp + 26
3  libsystem_platform.dylib 0x00007fff5ee4f9a0 _sigtramp + 3561593504
4  libsystem_c.dylib        0x00007fff8cb9fb53 abort + 129
5  libsystem_c.dylib        0x00007fff8cb67c39 basename + 0
6  swift                    0x000000010149b286 swift::ArchetypeBuilder::finalize(swift::SourceLoc) + 2534
7  swift                    0x000000010145de69 swift::TypeChecker::validateGenericSignature(swift::GenericParamList*, swift::DeclContext*, swift::GenericSignature*, std::__1::function<bool (swift::ArchetypeBuilder&)>, bool&) + 201
8  swift                    0x000000010144083a checkExtensionGenericParams(swift::TypeChecker&, swift::ExtensionDecl*, swift::Type, swift::GenericParamList*, swift::GenericSignature*&) + 426
9  swift                    0x000000010143761f swift::TypeChecker::validateExtension(swift::ExtensionDecl*) + 239
10 swift                    0x0000000101445dd3 (anonymous namespace)::DeclChecker::visitExtensionDecl(swift::ExtensionDecl*) + 35
…
Stack dump:
0.	Program arguments: /Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file boom.swift -target x86_64-apple-darwin14.3.0 -enable-objc-interop -module-name boom -o /var/folders/9y/f7n4rvx901nctm_5d16c1wm40000gn/T/boom-a3edd8.o 
1.	While type-checking declaration 0x7ffb2189a450 at boom.swift:9:1
<unknown>:0: error: unable to execute command: Abort trap: 6
<unknown>:0: error: swift frontend command failed due to signal (use -v to see invocation)


Regression:
N/A

Notes:
N/A