Check for system include paths by looking at clang's HeaderSearchOptions,

tools/clang/translation_unit/TranslationUnitGenerator.cpp

Index: tools/clang/translation_unit/TranslationUnitGenerator.cpp
diff --git a/tools/clang/translation_unit/TranslationUnitGenerator.cpp b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
index 5db8d640b74c5c6e5b6328c9ee7ab49e6f8cbe95..3590b0c4ea30d7a1719e1a16348e42b2397070e9 100644
--- a/tools/clang/translation_unit/TranslationUnitGenerator.cpp
+++ b/tools/clang/translation_unit/TranslationUnitGenerator.cpp
@@ -23,6 +23,7 @@
 #include "clang/Basic/SourceManager.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendActions.h"
+#include "clang/Lex/HeaderSearchOptions.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Tooling/CommonOptionsParser.h"
@@ -31,6 +32,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/Support/CommandLine.h"
 
+using clang::HeaderSearchOptions;
 using clang::tooling::CommonOptionsParser;
 using std::set;
 using std::stack;
@@ -43,10 +45,8 @@ class IncludeFinderPPCallbacks : public clang::PPCallbacks {
  public:
   IncludeFinderPPCallbacks(clang::SourceManager* source_manager,
                            string* main_source_file,
-                           set<string>* source_file_paths)
-      : source_manager_(source_manager),
-        main_source_file_(main_source_file),
-        source_file_paths_(source_file_paths) {}
+                           set<string>* source_file_paths,
+                           const HeaderSearchOptions* header_search_options);
   void FileChanged(clang::SourceLocation /*loc*/,
                    clang::PPCallbacks::FileChangeReason reason,
                    clang::SrcMgr::CharacteristicKind /*file_type*/,
@@ -64,9 +64,13 @@ class IncludeFinderPPCallbacks : public clang::PPCallbacks {
   void EndOfMainFile() override;
 
  private:
+  string DoubleSlashSystemHeaders(const string& search_path,
+                                  const string& relative_path) const;
+
   clang::SourceManager* const source_manager_;
   string* const main_source_file_;
   set<string>* const source_file_paths_;
+  set<string> system_header_prefixes_;
   // The path of the file that was last referenced by an inclusion directive,
   // normalized for includes that are relative to a different source file.
   string last_inclusion_directive_;
@@ -74,6 +78,39 @@ class IncludeFinderPPCallbacks : public clang::PPCallbacks {
   stack<string> current_files_;
 };
 
+IncludeFinderPPCallbacks::IncludeFinderPPCallbacks(
+    clang::SourceManager* source_manager,
+    string* main_source_file,
+    set<string>* source_file_paths,
+    const HeaderSearchOptions* header_search_options)
+      : source_manager_(source_manager),
+        main_source_file_(main_source_file),
+        source_file_paths_(source_file_paths) {
+  // In practice this list seems to be empty, but add it anyway just in case.
+  for (const auto& prefix : header_search_options->SystemHeaderPrefixes) {
+    system_header_prefixes_.insert(prefix.Prefix);
+  }
+
+  // This list contains all the include directories of different type.  We add
+  // all system headers to the set - excluding the Quoted and Angled groups
+  // which are from -iquote and -I flags.
+  for (const auto& entry : header_search_options->UserEntries) {
+    switch (entry.Group) {
+      case clang::frontend::System:
+      case clang::frontend::ExternCSystem:
+      case clang::frontend::CSystem:
+      case clang::frontend::CXXSystem:
+      case clang::frontend::ObjCSystem:
+      case clang::frontend::ObjCXXSystem:
+      case clang::frontend::After:
+        system_header_prefixes_.insert(entry.Path);
+        break;
+      default:
+        break;
+    }
+  }
+}
+
 void IncludeFinderPPCallbacks::FileChanged(
     clang::SourceLocation /*loc*/,
     clang::PPCallbacks::FileChangeReason reason,
@@ -135,21 +172,30 @@ void IncludeFinderPPCallbacks::InclusionDirective(
 
     // Otherwise we take the literal path as we stored it for the current
     // file, and append the relative path.
-    last_inclusion_directive_ = parent + "/" + relative_path.str();
+    last_inclusion_directive_ =
+        DoubleSlashSystemHeaders(parent, relative_path.str());
   } else if (!search_path.empty()) {
-    // We want to be able to extract the search path relative to which the
-    // include statement is defined. Therefore if search_path is an absolute
-    // path (indicating it is most likely a system header) we use "//" as a
-    // separator between the search path and the relative path.
-    last_inclusion_directive_ = search_path.str() +
-        (llvm::sys::path::is_absolute(search_path) ? "//" : "/") +
-        relative_path.str();
+    last_inclusion_directive_ =
+        DoubleSlashSystemHeaders(search_path.str(), relative_path.str());
   } else {
     last_inclusion_directive_ = file_name.str();
   }
   AddFile(last_inclusion_directive_);
 }
 
+string IncludeFinderPPCallbacks::DoubleSlashSystemHeaders(
+    const string& search_path,
+    const string& relative_path) const {
+  // We want to be able to extract the search path relative to which the
+  // include statement is defined. Therefore if search_path is a system header
+  // we use "//" as a separator between the search path and the relative path.
+  const bool is_system_header =
+      system_header_prefixes_.find(search_path) !=
+      system_header_prefixes_.end();
+
+  return search_path + (is_system_header ? "//" : "/") + relative_path;
+}
+
 void IncludeFinderPPCallbacks::EndOfMainFile() {
   const clang::FileEntry* main_file =
       source_manager_->getFileEntryForID(source_manager_->getMainFileID());
@@ -190,7 +236,8 @@ void CompilationIndexerAction::Preprocess() {
   preprocessor.addPPCallbacks(llvm::make_unique<IncludeFinderPPCallbacks>(
       &getCompilerInstance().getSourceManager(),
       &main_source_file_,
-      &source_file_paths_));
+      &source_file_paths_,
+      &getCompilerInstance().getHeaderSearchOpts()));
   preprocessor.getDiagnostics().setIgnoreAllWarnings(true);
   preprocessor.SetSuppressIncludeNotFoundError(true);
   preprocessor.EnterMainSourceFile();
@@ -202,7 +249,7 @@ void CompilationIndexerAction::Preprocess() {
 
 void CompilationIndexerAction::EndSourceFileAction() {
   std::ofstream out(main_source_file_ + ".filepaths");
-  for (string path : source_file_paths_) {
+  for (const string& path : source_file_paths_) {

[dcheng, 2016/02/03 05:18:33]

Oops.

     out << path << std::endl;
   }
 }