Use the name of the file on disk to issue a new diagnostic about non-portable #include and #import paths.

Differential Revision: http://reviews.llvm.org/D19843
Corresponding LLVM change: http://reviews.llvm.org/D19842

Re-commit after addressing issues with of generating too many warnings for Windows and asan test failures.

Patch by Eric Niebler

llvm-svn: 272562

2 files changed, 15 insertions, 4 deletions

diff --git a/clang/lib/Basic/FileManager.cpp b/clang/lib/Basic/FileManager.cpp
index c4cc8dc5419..ce9b7e1bb48 100644
--- a/clang/lib/Basic/FileManager.cpp
+++ b/clang/lib/Basic/FileManager.cpp
@@ -312,6 +312,9 @@ const FileEntry *FileManager::getFile(StringRef Filename, bool openFile,
   UFE.InPCH = Data.InPCH;
   UFE.File = std::move(F);
   UFE.IsValid = true;
+  if (UFE.File)
+    if (auto RealPathName = UFE.File->getName())
+      UFE.RealPathName = *RealPathName;
   return &UFE;
 }
 
diff --git a/clang/lib/Basic/VirtualFileSystem.cpp b/clang/lib/Basic/VirtualFileSystem.cpp
index 2eb7a84521f..8ace2b3dc83 100644
--- a/clang/lib/Basic/VirtualFileSystem.cpp
+++ b/clang/lib/Basic/VirtualFileSystem.cpp
@@ -140,16 +140,19 @@ namespace {
 class RealFile : public File {
   int FD;
   Status S;
+  std::string RealName;
   friend class RealFileSystem;
-  RealFile(int FD, StringRef NewName)
+  RealFile(int FD, StringRef NewName, StringRef NewRealPathName)
       : FD(FD), S(NewName, {}, {}, {}, {}, {},
-                  llvm::sys::fs::file_type::status_error, {}) {
+                  llvm::sys::fs::file_type::status_error, {}),
+        RealName(NewRealPathName.str()) {
     assert(FD >= 0 && "Invalid or inactive file descriptor");
   }
 
 public:
   ~RealFile() override;
   ErrorOr<Status> status() override;
+  ErrorOr<std::string> getName() override;
   ErrorOr<std::unique_ptr<MemoryBuffer>> getBuffer(const Twine &Name,
                                                    int64_t FileSize,
                                                    bool RequiresNullTerminator,
@@ -170,6 +173,10 @@ ErrorOr<Status> RealFile::status() {
   return S;
 }
 
+ErrorOr<std::string> RealFile::getName() {
+  return RealName.empty() ? S.getName().str() : RealName;
+}
+
 ErrorOr<std::unique_ptr<MemoryBuffer>>
 RealFile::getBuffer(const Twine &Name, int64_t FileSize,
                     bool RequiresNullTerminator, bool IsVolatile) {
@@ -207,9 +214,10 @@ ErrorOr<Status> RealFileSystem::status(const Twine &Path) {
 ErrorOr<std::unique_ptr<File>>
 RealFileSystem::openFileForRead(const Twine &Name) {
   int FD;
-  if (std::error_code EC = sys::fs::openFileForRead(Name, FD))
+  SmallString<256> RealName;
+  if (std::error_code EC = sys::fs::openFileForRead(Name, FD, &RealName))
     return EC;
-  return std::unique_ptr<File>(new RealFile(FD, Name.str()));
+  return std::unique_ptr<File>(new RealFile(FD, Name.str(), RealName.str()));
 }
 
 llvm::ErrorOr<std::string> RealFileSystem::getCurrentWorkingDirectory() const {