import Foundation

public protocol A: RawRepresentable {}
extension A {
  static func +(lhs: RawValue, rhs: Self) -> Self {
    return Self(rawValue: rhs + lhs.rawValue)!
  }
}

open class Foo<Bar: NSObject> {
  fileprivate var foobar: Bar {
    fatalError()
  }
  lazy var foo: () -> () = { [weak self] in
    guard let a = self else { return }
    _ = a.foobar + nil
  }
}

1.  While type-checking 'Foo' at /tmp/dasdasdf/dasdasdf/main.swift:18:6
2.  While type-checking declaration 0x7fe92f060050 at /tmp/dasdasdf/dasdasdf/main.swift:22:8
3.  While type-checking expression at [/tmp/dasdasdf/dasdasdf/main.swift:22:28 - line:25:3] RangeText="{ [weak self] in
    guard let a = self else { return }
    _ = a.foobar + nil
  "
4.  While type-checking statement at [/tmp/dasdasdf/dasdasdf/main.swift:22:28 - line:25:3] RangeText="{ [weak self] in
    guard let a = self else { return }
    _ = a.foobar + nil
  "
5.  While type-checking expression at [/tmp/dasdasdf/dasdasdf/main.swift:24:5 - line:24:20] RangeText="_ = a.foobar + "
 

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   swift                           0x000000010828c7a0 swift::GenericContext::getGenericSignature() const + 16
1   swift                           0x0000000107e756a0 swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 5584
2   swift                           0x0000000107f158a7 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 1319
3   swift                           0x0000000107ecf408 swift::constraints::ConstraintSystem::solve(swift::Expr*&, swift::Type, swift::ExprTypeCheckListener*, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::FreeTypeVariableBinding) + 72
4   swift                           0x0000000107f70817 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) + 951
5   swift                           0x0000000107ffe1e8 swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 584
6   swift                           0x0000000107ffd498 bool (anonymous namespace)::StmtChecker::typeCheckStmt<swift::BraceStmt>(swift::BraceStmt*&) + 136
7   swift                           0x0000000107ffd24c swift::TypeChecker::typeCheckClosureBody(swift::ClosureExpr*) + 268
8   swift                           0x0000000107e4e02b swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::Expr*, swift::Type, bool, bool) + 555
9   swift                           0x0000000107f708cc swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::TypeLoc, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem*) + 1132
10  swift                           0x0000000107f75965 swift::TypeChecker::typeCheckBinding(swift::Pattern*&, swift::Expr*&, swift::DeclContext*, bool) + 357
11  swift                           0x0000000107f75c6b swift::TypeChecker::typeCheckPatternBinding(swift::PatternBindingDecl*, unsigned int, bool) + 315
12  swift                           0x0000000107f84d04 (anonymous namespace)::DeclChecker::visit(swift::Decl*) + 2484
13  swift                           0x0000000107f9120b (anonymous namespace)::DeclChecker::visitClassDecl(swift::ClassDecl*) + 267
14  swift                           0x0000000107f8466e (anonymous namespace)::DeclChecker::visit(swift::Decl*) + 798
15  swift                           0x0000000107f84346 swift::TypeChecker::typeCheckDecl(swift::Decl*) + 38
16  swift                           0x000000010801def8 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int, unsigned int, unsigned int, unsigned int, unsigned int) + 872
17  swift                           0x000000010782a53c swift::CompilerInstance::parseAndTypeCheckMainFileUpTo(swift::SourceFile::ASTStage_t, swift::PersistentParserState&, swift::DelayedParsingCallbacks*, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>) + 492
18  swift                           0x0000000107829173 swift::CompilerInstance::parseAndCheckTypesUpTo(swift::CompilerInstance::ImplicitImports const&, swift::SourceFile::ASTStage_t) + 435
19  swift                           0x0000000107828838 swift::CompilerInstance::performSemaUpTo(swift::SourceFile::ASTStage_t) + 616
20  swift                           0x0000000106febc4d performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*, swift::UnifiedStatsReporter*) + 1309
21  swift                           0x0000000106fea69d swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3021
22  swift                           0x0000000106f9c6de main + 686
23  libdyld.dylib                   0x00007fff742fd085 start + 1