Index: clang-tools-extra/trunk/clangd/GlobalCompilationDatabase.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/GlobalCompilationDatabase.cpp
+++ clang-tools-extra/trunk/clangd/GlobalCompilationDatabase.cpp
@@ -58,9 +58,11 @@
 tooling::CompileCommand
 GlobalCompilationDatabase::getFallbackCommand(PathRef File) const {
   std::vector<std::string> Argv = {getFallbackClangPath()};
-  // Clang treats .h files as C by default, resulting in unhelpful diagnostics.
+  // Clang treats .h files as C by default and files without extension as linker
+  // input, resulting in unhelpful diagnostics.
   // Parsing as Objective C++ is friendly to more cases.
-  if (llvm::sys::path::extension(File) == ".h")
+  auto FileExtension = llvm::sys::path::extension(File);
+  if (FileExtension.empty() || FileExtension == ".h")
     Argv.push_back("-xobjective-c++-header");
   Argv.push_back(File);
   tooling::CompileCommand Cmd(llvm::sys::path::parent_path(File),
Index: clang-tools-extra/trunk/clangd/unittests/GlobalCompilationDatabaseTests.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/unittests/GlobalCompilationDatabaseTests.cpp
+++ clang-tools-extra/trunk/clangd/unittests/GlobalCompilationDatabaseTests.cpp
@@ -36,6 +36,10 @@
   EXPECT_THAT(Cmd.CommandLine,
               ElementsAre(EndsWith("clang"), "-xobjective-c++-header",
                           testPath("foo/bar.h")));
+  Cmd = DB.getFallbackCommand(testPath("foo/bar"));
+  EXPECT_THAT(Cmd.CommandLine,
+              ElementsAre(EndsWith("clang"), "-xobjective-c++-header",
+                          testPath("foo/bar")));
 }
 
 static tooling::CompileCommand cmd(llvm::StringRef File, llvm::StringRef Arg) {