Index: cfe/trunk/lib/CodeGen/CGObjCMac.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGObjCMac.cpp
+++ cfe/trunk/lib/CodeGen/CGObjCMac.cpp
@@ -4921,7 +4921,7 @@
 std::string CGObjCCommonMac::GetSectionName(StringRef Section,
                                             StringRef MachOAttributes) {
   switch (CGM.getTriple().getObjectFormat()) {
-  default:
+  case llvm::Triple::UnknownObjectFormat:
     llvm_unreachable("unexpected object file format");
   case llvm::Triple::MachO: {
     if (MachOAttributes.empty())
@@ -4936,6 +4936,10 @@
     assert(Section.substr(0, 2) == "__" &&
            "expected the name to begin with __");
     return ("." + Section.substr(2) + "$B").str();
+  case llvm::Triple::Wasm:
+  case llvm::Triple::XCOFF:
+    llvm::report_fatal_error(
+        "Objective-C support is unimplemented for object file format.");
   }
 }
 
Index: llvm/trunk/include/llvm/Support/TargetRegistry.h
===================================================================
--- llvm/trunk/include/llvm/Support/TargetRegistry.h
+++ llvm/trunk/include/llvm/Support/TargetRegistry.h
@@ -470,7 +470,7 @@
                                      bool DWARFMustBeAtTheEnd) const {
     MCStreamer *S;
     switch (T.getObjectFormat()) {
-    default:
+    case Triple::UnknownObjectFormat:
       llvm_unreachable("Unknown object format");
     case Triple::COFF:
       assert(T.isOSWindows() && "only Windows COFF is supported");
@@ -504,6 +504,8 @@
         S = createWasmStreamer(Ctx, std::move(TAB), std::move(OW),
                                std::move(Emitter), RelaxAll);
       break;
+    case Triple::XCOFF:
+      report_fatal_error("XCOFF MCObjectStreamer not implemented yet.");
     }
     if (ObjectTargetStreamerCtorFn)
       ObjectTargetStreamerCtorFn(*S, STI);