Open Radar

 
Summary:
- For the last several Xcode releases, it’s been impossible to develop on the attached project without SourceKit immediately crashing.

Steps to Reproduce:
- Unzip attached file.
- Open `ReactiveCocoa.xcworkspace`.
- Select `ReactiveCocoa-iOS` scheme.
- Open `SignalProducer.swift`

Expected Results:
- You can easily edit the file with syntax highlighting and autocompletion.

Actual Results:
- SourceKit crashes right away:

Thread 5 Crashed:
0   com.apple.SourceKitService    	0x0000000107614b7f (anonymous namespace)::ExprWalker::walkToExprPre(swift::Expr*) + 575
1   com.apple.SourceKitService    	0x000000010776abda swift::Expr::walk(swift::ASTWalker&) + 26
2   com.apple.SourceKitService    	0x000000010760e9a9 swift::constraints::ConstraintSystem::applySolution(swift::constraints::Solution&, swift::Expr*, swift::Type, bool, bool, bool) + 473
3   com.apple.SourceKitService    	0x0000000107693b2e swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*) + 782
4   com.apple.SourceKitService    	0x000000010762da9a (anonymous namespace)::FailureDiagnosis::typeCheckChildIndependently(swift::Expr*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<TCCFlags, unsigned int>, swift::ExprTypeCheckListener*) + 1002
5   com.apple.SourceKitService    	0x0000000107632656 (anonymous namespace)::FailureDiagnosis::visitApplyExpr(swift::ApplyExpr*) + 1318
6   com.apple.SourceKitService    	0x0000000107629488 swift::ASTVisitor<(anonymous namespace)::FailureDiagnosis, bool, void, void, void, void, void>::visit(swift::Expr*) + 264
7   com.apple.SourceKitService    	0x0000000107624ae2 swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 82
8   com.apple.SourceKitService    	0x0000000107628f82 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 4194
9   com.apple.SourceKitService    	0x000000010768e1b0 swift::TypeChecker::solveForExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::FreeTypeVariableBinding, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem&, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 736
10  com.apple.SourceKitService    	0x0000000107693a42 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*) + 546
11  com.apple.SourceKitService    	0x000000010762da9a (anonymous namespace)::FailureDiagnosis::typeCheckChildIndependently(swift::Expr*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<TCCFlags, unsigned int>, swift::ExprTypeCheckListener*) + 1002
12  com.apple.SourceKitService    	0x0000000107624b28 swift::constraints::ConstraintSystem::diagnoseFailureForExpr(swift::Expr*) + 152
13  com.apple.SourceKitService    	0x0000000107628f82 swift::constraints::ConstraintSystem::salvage(llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::Expr*) + 4194
14  com.apple.SourceKitService    	0x000000010768e1b0 swift::TypeChecker::solveForExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::FreeTypeVariableBinding, swift::ExprTypeCheckListener*, swift::constraints::ConstraintSystem&, llvm::SmallVectorImpl<swift::constraints::Solution>&, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>) + 736
15  com.apple.SourceKitService    	0x0000000107693a42 swift::TypeChecker::typeCheckExpression(swift::Expr*&, swift::DeclContext*, swift::Type, swift::ContextualTypePurpose, swift::OptionSet<swift::TypeCheckExprFlags, unsigned int>, swift::ExprTypeCheckListener*) + 546
16  com.apple.SourceKitService    	0x00000001076e5deb swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 4411
17  com.apple.SourceKitService    	0x00000001076e4dbb swift::ASTVisitor<(anonymous namespace)::StmtChecker, void, swift::Stmt*, void, void, void, void>::visit(swift::Stmt*) + 267
18  com.apple.SourceKitService    	0x00000001076e3a3b swift::TypeChecker::typeCheckFunctionBodyUntil(swift::FuncDecl*, swift::SourceLoc) + 347
19  com.apple.SourceKitService    	0x00000001076e42ea swift::TypeChecker::typeCheckAbstractFunctionBody(swift::AbstractFunctionDecl*) + 186
20  com.apple.SourceKitService    	0x000000010767cd86 typeCheckFunctionsAndExternalDecls(swift::TypeChecker&) + 182
21  com.apple.SourceKitService    	0x000000010767d9e5 swift::performTypeChecking(swift::SourceFile&, swift::TopLevelContext&, swift::OptionSet<swift::TypeCheckingFlags, unsigned int>, unsigned int) + 1781
22  com.apple.SourceKitService    	0x00000001072a10c2 swift::CompilerInstance::performSema() + 4738
23  com.apple.SourceKitService    	0x000000010716663e void SourceKit::WorkQueue::DispatchData::callAndDelete<(anonymous namespace)::ASTProducer::getASTUnitAsync(SourceKit::SwiftASTManager::Implementation&, llvm::ArrayRef<llvm::IntrusiveRefCntPtr<SourceKit::ImmutableTextSnapshot> >, std::__1::function<void (llvm::IntrusiveRefCntPtr<SourceKit::ASTUnit>, llvm::StringRef)>)::$_2>(void*) + 5806
24  libdispatch.dylib             	0x00007fff915bf33f _dispatch_client_callout + 8
25  libdispatch.dylib             	0x00007fff915cd03a _dispatch_block_invoke + 474
26  com.apple.SourceKitService    	0x00000001089acbbf executeBlock(void*) + 15
27  com.apple.SourceKitService    	0x000000010723b58d ExecuteOnThread_Dispatch(void*) + 13
28  libsystem_pthread.dylib       	0x00007fff98f84c13 _pthread_body + 131
29  libsystem_pthread.dylib       	0x00007fff98f84b90 _pthread_start + 168
30  libsystem_pthread.dylib       	0x00007fff98f82375 thread_start + 13


Regression:
This has been happening at least since Xcode 7.2, although SourceKit has never really been stable.