Index: clang-tools-extra/trunk/clang-tidy/utils/HeaderGuard.cpp
===================================================================
--- clang-tools-extra/trunk/clang-tidy/utils/HeaderGuard.cpp
+++ clang-tools-extra/trunk/clang-tidy/utils/HeaderGuard.cpp
@@ -223,9 +223,10 @@
 
       std::string CPPVar = Check->getHeaderGuard(FileName);
       std::string CPPVarUnder = CPPVar + '_'; // Allow a trailing underscore.
-      // If there is a header guard macro but it's not in the topmost position
-      // emit a plain warning without fix-its. This often happens when the guard
-      // macro is preceeded by includes.
+      // If there's a macro with a name that follows the header guard convention
+      // but was not recognized by the preprocessor as a header guard there must
+      // be code outside of the guarded area. Emit a plain warning without
+      // fix-its.
       // FIXME: Can we move it into the right spot?
       bool SeenMacro = false;
       for (const auto &MacroEntry : Macros) {
@@ -233,9 +234,8 @@
         SourceLocation DefineLoc = MacroEntry.first.getLocation();
         if ((Name == CPPVar || Name == CPPVarUnder) &&
             SM.isWrittenInSameFile(StartLoc, DefineLoc)) {
-          Check->diag(
-              DefineLoc,
-              "Header guard after code/includes. Consider moving it up.");
+          Check->diag(DefineLoc, "code/includes outside of area guarded by "
+                                 "header guard; consider moving it");
           SeenMacro = true;
           break;
         }
Index: clang-tools-extra/trunk/unittests/clang-tidy/LLVMModuleTest.cpp
===================================================================
--- clang-tools-extra/trunk/unittests/clang-tidy/LLVMModuleTest.cpp
+++ clang-tools-extra/trunk/unittests/clang-tidy/LLVMModuleTest.cpp
@@ -12,11 +12,16 @@
 // FIXME: It seems this might be incompatible to dos path. Investigating.
 #if !defined(_WIN32)
 static std::string runHeaderGuardCheck(StringRef Code, const Twine &Filename,
-                                       unsigned ExpectedWarnings) {
+                                       Optional<StringRef> ExpectedWarning) {
   std::vector<ClangTidyError> Errors;
   std::string Result = test::runCheckOnCode<LLVMHeaderGuardCheck>(
       Code, &Errors, Filename, std::string("-xc++-header"));
-  return Errors.size() == ExpectedWarnings ? Result : "invalid error count";
+  if (Errors.size() != (size_t)ExpectedWarning.hasValue())
+    return "invalid error count";
+  if (ExpectedWarning && *ExpectedWarning != Errors.back().Message.Message)
+    return "expected: '" + ExpectedWarning->str() + "', saw: '" +
+           Errors.back().Message.Message + "'";
+  return Result;
 }
 
 namespace {
@@ -27,24 +32,30 @@
 };
 } // namespace
 
-static std::string runHeaderGuardCheckWithEndif(StringRef Code,
-                                                const Twine &Filename,
-                                                unsigned ExpectedWarnings) {
+static std::string
+runHeaderGuardCheckWithEndif(StringRef Code, const Twine &Filename,
+                             Optional<StringRef> ExpectedWarning) {
   std::vector<ClangTidyError> Errors;
   std::string Result = test::runCheckOnCode<WithEndifComment>(
       Code, &Errors, Filename, std::string("-xc++-header"));
-  return Errors.size() == ExpectedWarnings ? Result : "invalid error count";
+  if (Errors.size() != (size_t)ExpectedWarning.hasValue())
+    return "invalid error count";
+  if (ExpectedWarning && *ExpectedWarning != Errors.back().Message.Message)
+    return "expected: '" + ExpectedWarning->str() + "', saw: '" +
+           Errors.back().Message.Message + "'";
+  return Result;
 }
 
 TEST(LLVMHeaderGuardCheckTest, FixHeaderGuards) {
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif\n",
-            runHeaderGuardCheck("#ifndef FOO\n"
-                                "#define FOO\n"
-                                "#endif\n",
-                                "include/llvm/ADT/foo.h",
-                                /*ExpectedWarnings=*/1));
+            runHeaderGuardCheck(
+                "#ifndef FOO\n"
+                "#define FOO\n"
+                "#endif\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("header guard does not follow preferred style")));
 
   // Allow trailing underscores.
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H_\n"
@@ -53,8 +64,7 @@
             runHeaderGuardCheck("#ifndef LLVM_ADT_FOO_H_\n"
                                 "#define LLVM_ADT_FOO_H_\n"
                                 "#endif\n",
-                                "include/llvm/ADT/foo.h",
-                                /*ExpectedWarnings=*/0));
+                                "include/llvm/ADT/foo.h", None));
 
   EXPECT_EQ("#ifndef LLVM_CLANG_C_BAR_H\n"
             "#define LLVM_CLANG_C_BAR_H\n"
@@ -62,7 +72,7 @@
             "\n"
             "#endif\n",
             runHeaderGuardCheck("", "./include/clang-c/bar.h",
-                                /*ExpectedWarnings=*/1));
+                                StringRef("header is missing header guard")));
 
   EXPECT_EQ("#ifndef LLVM_CLANG_LIB_CODEGEN_C_H\n"
             "#define LLVM_CLANG_LIB_CODEGEN_C_H\n"
@@ -70,7 +80,7 @@
             "\n"
             "#endif\n",
             runHeaderGuardCheck("", "tools/clang/lib/CodeGen/c.h",
-                                /*ExpectedWarnings=*/1));
+                                StringRef("header is missing header guard")));
 
   EXPECT_EQ("#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_X_H\n"
             "#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_X_H\n"
@@ -78,17 +88,33 @@
             "\n"
             "#endif\n",
             runHeaderGuardCheck("", "tools/clang/tools/extra/clang-tidy/x.h",
-                                /*ExpectedWarnings=*/1));
+                                StringRef("header is missing header guard")));
 
-  EXPECT_EQ("int foo;\n"
-            "#ifndef LLVM_CLANG_BAR_H\n"
-            "#define LLVM_CLANG_BAR_H\n"
-            "#endif\n",
-            runHeaderGuardCheck("int foo;\n"
-                                "#ifndef LLVM_CLANG_BAR_H\n"
-                                "#define LLVM_CLANG_BAR_H\n"
-                                "#endif\n",
-                                "include/clang/bar.h", /*ExpectedWarnings=*/1));
+  EXPECT_EQ(
+      "int foo;\n"
+      "#ifndef LLVM_CLANG_BAR_H\n"
+      "#define LLVM_CLANG_BAR_H\n"
+      "#endif\n",
+      runHeaderGuardCheck("int foo;\n"
+                          "#ifndef LLVM_CLANG_BAR_H\n"
+                          "#define LLVM_CLANG_BAR_H\n"
+                          "#endif\n",
+                          "include/clang/bar.h",
+                          StringRef("code/includes outside of area guarded by "
+                                    "header guard; consider moving it")));
+
+  EXPECT_EQ(
+      "#ifndef LLVM_CLANG_BAR_H\n"
+      "#define LLVM_CLANG_BAR_H\n"
+      "#endif\n"
+      "int foo;\n",
+      runHeaderGuardCheck("#ifndef LLVM_CLANG_BAR_H\n"
+                          "#define LLVM_CLANG_BAR_H\n"
+                          "#endif\n"
+                          "int foo;\n",
+                          "include/clang/bar.h",
+                          StringRef("code/includes outside of area guarded by "
+                                    "header guard; consider moving it")));
 
   EXPECT_EQ("#ifndef LLVM_CLANG_BAR_H\n"
             "#define LLVM_CLANG_BAR_H\n"
@@ -103,35 +129,40 @@
                                 "#ifndef FOOLOLO\n"
                                 "#define FOOLOLO\n"
                                 "#endif\n",
-                                "include/clang/bar.h", /*ExpectedWarnings=*/1));
+                                "include/clang/bar.h",
+                                StringRef("header is missing header guard")));
 
   // Fix incorrect #endif comments even if we shouldn't add new ones.
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif // LLVM_ADT_FOO_H\n",
-            runHeaderGuardCheck("#ifndef FOO\n"
-                                "#define FOO\n"
-                                "#endif // FOO\n",
-                                "include/llvm/ADT/foo.h",
-                                /*ExpectedWarnings=*/1));
+            runHeaderGuardCheck(
+                "#ifndef FOO\n"
+                "#define FOO\n"
+                "#endif // FOO\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("header guard does not follow preferred style")));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif // LLVM_ADT_FOO_H\n",
-            runHeaderGuardCheckWithEndif("#ifndef FOO\n"
-                                         "#define FOO\n"
-                                         "#endif\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/1));
+            runHeaderGuardCheckWithEndif(
+                "#ifndef FOO\n"
+                "#define FOO\n"
+                "#endif\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("header guard does not follow preferred style")));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif // LLVM_ADT_FOO_H\n",
-            runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H\n"
-                                         "#define LLVM_ADT_FOO_H\n"
-                                         "#endif // LLVM_H\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/1));
+            runHeaderGuardCheckWithEndif(
+                "#ifndef LLVM_ADT_FOO_H\n"
+                "#define LLVM_ADT_FOO_H\n"
+                "#endif // LLVM_H\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("#endif for a header guard should reference the "
+                          "guard macro in a comment")));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
@@ -139,8 +170,7 @@
             runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H\n"
                                          "#define LLVM_ADT_FOO_H\n"
                                          "#endif /* LLVM_ADT_FOO_H */\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/0));
+                                         "include/llvm/ADT/foo.h", None));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H_\n"
             "#define LLVM_ADT_FOO_H_\n"
@@ -148,28 +178,29 @@
             runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H_\n"
                                          "#define LLVM_ADT_FOO_H_\n"
                                          "#endif // LLVM_ADT_FOO_H_\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/0));
+                                         "include/llvm/ADT/foo.h", None));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif // LLVM_ADT_FOO_H\n",
-            runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H_\n"
-                                         "#define LLVM_ADT_FOO_H_\n"
-                                         "#endif // LLVM\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/1));
+            runHeaderGuardCheckWithEndif(
+                "#ifndef LLVM_ADT_FOO_H_\n"
+                "#define LLVM_ADT_FOO_H_\n"
+                "#endif // LLVM\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("header guard does not follow preferred style")));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
             "#endif \\ \n"
             "// LLVM_ADT_FOO_H\n",
-            runHeaderGuardCheckWithEndif("#ifndef LLVM_ADT_FOO_H\n"
-                                         "#define LLVM_ADT_FOO_H\n"
-                                         "#endif \\ \n"
-                                         "// LLVM_ADT_FOO_H\n",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/1));
+            runHeaderGuardCheckWithEndif(
+                "#ifndef LLVM_ADT_FOO_H\n"
+                "#define LLVM_ADT_FOO_H\n"
+                "#endif \\ \n"
+                "// LLVM_ADT_FOO_H\n",
+                "include/llvm/ADT/foo.h",
+                StringRef("backslash and newline separated by space")));
 
   EXPECT_EQ("#ifndef LLVM_ADT_FOO_H\n"
             "#define LLVM_ADT_FOO_H\n"
@@ -179,8 +210,7 @@
                                          "#define LLVM_ADT_FOO_H\n"
                                          "#endif  /* LLVM_ADT_FOO_H\\ \n"
                                          " FOO */",
-                                         "include/llvm/ADT/foo.h",
-                                         /*ExpectedWarnings=*/0));
+                                         "include/llvm/ADT/foo.h", None));
 }
 #endif