[clang-tidy] Make llvm-header-guard work on llvm git monorepo

[hokein]

upload correct diff.

clang-tools-extra/trunk/clang-tidy/llvm/HeaderGuardCheck.cpp

std::string LLVMHeaderGuardCheck::getHeaderGuard(StringRef Filename,
   if (PosInclude != StringRef::npos)
     Guard = Guard.substr(PosInclude + std::strlen("include/"));
 
   // For clang we drop the _TOOLS_.
   size_t PosToolsClang = Guard.rfind("tools/clang/");
   if (PosToolsClang != StringRef::npos)
     Guard = Guard.substr(PosToolsClang + std::strlen("tools/"));
 
+  // Unlike LLVM svn, LLVM git monorepo is named llvm-project, so we replace
+  // "/llvm-project/" with the cannonical "/llvm/".
+  const static StringRef LLVMProject = "/llvm-project/";
+  size_t PosLLVMProject = Guard.rfind(LLVMProject);
+  if (PosLLVMProject != StringRef::npos)
+    Guard = Guard.replace(PosLLVMProject, LLVMProject.size(), "/llvm/");
+
   // The remainder is LLVM_FULL_PATH_TO_HEADER_H
   size_t PosLLVM = Guard.rfind("llvm/");
   if (PosLLVM != StringRef::npos)
     Guard = Guard.substr(PosLLVM);
 
   std::replace(Guard.begin(), Guard.end(), '/', '_');
   std::replace(Guard.begin(), Guard.end(), '.', '_');
   std::replace(Guard.begin(), Guard.end(), '-', '_');

clang-tools-extra/trunk/unittests/clang-tidy/LLVMModuleTest.cpp

EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif  /* LLVM_ADT_FOO_H\\ \n"
             " FOO */",
             runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H\n"
                                          "#define LLVM_ADT_FOO_H\n"
                                          "#endif  /* LLVM_ADT_FOO_H\\ \n"
                                          " FOO */",
                                          "include/llvm/ADT/foo.h", None));
+
+  EXPECT_EQ("#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FOO_H\n"
+            "#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FOO_H\n"
+            "\n"
+            "\n"
+            "#endif\n",
+            runHeaderGuardCheck(
+                "", "/llvm-project/clang-tools-extra/clangd/foo.h",
+                StringRef("header is missing header guard")));
 }
 #endif
 
 } // namespace test
 } // namespace tidy
 } // namespace clang