title: Debug merge .swiftmodule: segmentation fault: 11
body: <p>I'm trying to compile Swift 1.2 iOS project with XCode v. 6.3 (6D520o).
  It goes through "Compile Swift source files" with</p>
  
  <pre><code>&lt;unknown&gt;:0: error: unable to execute command: Segmentation fault: 11
  &lt;unknown&gt;:0: error: merge-module command failed due to signal (use -v to see invocation)
  </code></pre>
  
  <p>and crashes on "Merge Project.swiftmodule".</p>
  
  <p>Clang's stack trace:</p>
  
  <pre><code>0  swift                    0x000000010ffa8d38 llvm::sys::PrintStackTrace(__sFILE*) + 40
  1  swift                    0x000000010ffa9214 SignalHandler(int) + 452
  2  libsystem_platform.dylib 0x00007fff84503f1a _sigtramp + 26
  3  libsystem_c.dylib        0x00007fff91d6076c sprintf_l + 134
  4  swift                    0x000000011065a502 swift::getFullComment(swift::CommentContext&amp;, swift::Decl const*) + 34
  5  swift                    0x000000010fba0e5a (anonymous namespace)::ObjCPrinter::printAbstractFunction(swift::AbstractFunctionDecl*, bool, bool) + 58
  6  swift                    0x000000010fba03ce (anonymous namespace)::ObjCPrinter::visitVarDecl(swift::VarDecl*) + 126
  7  swift                    0x000000010fba55c1 (anonymous namespace)::ObjCPrinter::printMembers(swift::IteratorRange&lt;swift::DeclIterator&gt;) + 433
  8  swift                    0x000000010fba0202 swift::ASTVisitor&lt;(anonymous namespace)::ObjCPrinter, void, void, void, void, void, void&gt;::visit(swift::Decl*) + 3266
  9  swift                    0x000000010fb9e45c swift::printAsObjC(llvm::raw_ostream&amp;, swift::Module*, llvm::StringRef, swift::Accessibility) + 2876
  10 swift                    0x000000010f8a1bcc printAsObjC(std::__1::basic_string&lt;char, std::__1::char_traits&lt;char&gt;, std::__1::allocator&lt;char&gt; &gt; const&amp;, swift::Module*, llvm::StringRef, bool) + 332
  11 swift                    0x000000010f8a04b5 frontend_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) + 4901
  12 swift                    0x000000010f89efe6 main + 1814
  13 libdyld.dylib            0x00007fff8f6ca5c9 start + 1
  </code></pre>
  
  <p>And here is the <a href="http://ix.io/gnW">full output of Compile and Merge phases</a>.</p>
  
  <p>Is it possible to find the true cause of crash from the clang output?
  Or I have to delete code until it is works again?</p>