Fix MSVC control path warnings

Author: hughbe

lib/Index/Index.cpp

@@ -24,6 +24,7 @@
 #include "swift/Basic/StringExtras.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 
 using namespace swift;
@@ -570,6 +571,8 @@ bool IndexSwiftASTWalker::startEntity(Decl *D, IndexSymbol &Info) {
       EntitiesStack.push_back({D, Info.symInfo, Info.roles, {}});
       return true;
   }
+
+  llvm_unreachable("Unhandled IndexDataConsumer in switch.");
 }
 
 bool IndexSwiftASTWalker::startEntityDecl(ValueDecl *D) {

lib/Sema/TypeCheckProtocol.cpp

@@ -38,6 +38,7 @@
 #include "llvm/ADT/ScopedHashTable.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/SaveAndRestore.h"
 
 #define DEBUG_TYPE "protocol-conformance-checking"
@@ -5482,6 +5483,8 @@ bool TypeChecker::useObjectiveCBridgeableConformancesOfArgs(
     return anyUnsatisfied;
   }
   }
+
+  llvm_unreachable("Unhandled RequirementCheckResult in switch.");
 }
 
 void TypeChecker::useBridgedNSErrorConformances(DeclContext *dc, Type type) {