[clang-tidy] Add a generic header guard checker + LLVM implementation.

The implementation is split into a generic part and a LLVM-specific part.
Other codebases can implement it with their own style. The specific features
supported are:

- Verification (and fixing) of header guards against a style based on the file path
- Automatic insertion of header guards for headers that are missing them
- A warning when the header guard doesn't enable our fancy header guard optimization
(e.g. when there's an include preceeding the guard)
- Automatic insertion of a comment with the guard name after #endif.

For the LLVM style we disable #endif comments for now, they're not very common
in the codebase. We also only flag headers in the include directories, there
doesn't seem to be a common style outside.

Differential Revision: http://reviews.llvm.org/D4867

llvm-svn: 215548

4 files changed, 87 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt b/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
index d405874d347..6f07cd9c176 100644
--- a/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/llvm/CMakeLists.txt
@@ -1,6 +1,7 @@
 set(LLVM_LINK_COMPONENTS support)
 
 add_clang_library(clangTidyLLVMModule
+  HeaderGuardCheck.cpp
   IncludeOrderCheck.cpp
   LLVMTidyModule.cpp
   NamespaceCommentCheck.cpp
@@ -12,4 +13,5 @@ add_clang_library(clangTidyLLVMModule
   clangBasic
   clangLex
   clangTidy
+  clangTidyUtils
   )
diff --git a/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
new file mode 100644
index 00000000000..abb60368d65
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.cpp
@@ -0,0 +1,53 @@
+//===--- HeaderGuardCheck.cpp - clang-tidy --------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "HeaderGuardCheck.h"
+
+namespace clang {
+namespace tidy {
+
+bool LLVMHeaderGuardCheck::shouldFixHeaderGuard(StringRef Filename) {
+  return Filename.endswith(".h");
+}
+
+std::string LLVMHeaderGuardCheck::getHeaderGuard(StringRef Filename,
+                                                 StringRef OldGuard) {
+  std::string Guard = tooling::getAbsolutePath(Filename);
+
+  // Sanitize the path. There are some rules for compatibility with the historic
+  // style in include/llvm and include/clang which we want to preserve.
+
+  // We don't want _INCLUDE_ in our guards.
+  size_t PosInclude = Guard.rfind("include/");
+  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/"));
+
+  // 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(), '-', '_');
+
+  // The prevalent style in clang is LLVM_CLANG_FOO_BAR_H
+  if (StringRef(Guard).startswith("clang"))
+    Guard = "LLVM_" + Guard;
+
+  return StringRef(Guard).upper();
+}
+
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.h b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.h
new file mode 100644
index 00000000000..fa99f9967f0
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/llvm/HeaderGuardCheck.h
@@ -0,0 +1,29 @@
+//===--- HeaderGuardCheck.h - clang-tidy ------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_HEADER_GUARD_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_HEADER_GUARD_CHECK_H
+
+#include "../utils/HeaderGuard.h"
+
+namespace clang {
+namespace tidy {
+
+/// Finds and fixes header guards that do not adhere to LLVM style.
+class LLVMHeaderGuardCheck : public HeaderGuardCheck {
+public:
+  bool shouldSuggestEndifComment(StringRef Filename) override { return false; }
+  bool shouldFixHeaderGuard(StringRef Filename) override;
+  std::string getHeaderGuard(StringRef Filename, StringRef OldGuard) override;
+};
+
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_LLVM_HEADER_GUARD_CHECK_H
diff --git a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
index 0586525228b..a8ef6299028 100644
--- a/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
+++ b/clang-tools-extra/clang-tidy/llvm/LLVMTidyModule.cpp
@@ -10,6 +10,7 @@
 #include "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
+#include "HeaderGuardCheck.h"
 #include "IncludeOrderCheck.h"
 #include "NamespaceCommentCheck.h"
 #include "TwineLocalCheck.h"
@@ -21,6 +22,8 @@ class LLVMModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.addCheckFactory(
+        "llvm-header-guard", new ClangTidyCheckFactory<LLVMHeaderGuardCheck>());
+    CheckFactories.addCheckFactory(
         "llvm-include-order", new ClangTidyCheckFactory<IncludeOrderCheck>());
     CheckFactories.addCheckFactory(
         "llvm-namespace-comment",