Track skipped files in dependency scanning.

It's possible for a header to be a symlink to another header. In this
case both will be represented by clang::FileEntry with the same UID and
they'll use the same clang::HeaderFileInfo.

If you include both headers and use some single-inclusion mechanism
like a header guard or #import, one header will get a FileChanged
callback, and another FileSkipped.

So that we get an accurate dependency file, we therefore need to also
implement the FileSkipped callback in dependency scanning.

Patch by Pete Cooper.

Reviewers: bruno, pete

Reviewed By: bruno

Subscribers: cfe-commits, jkorous, vsapsai

Differential Revision: https://reviews.llvm.org/D30881

llvm-svn: 331319

1 files changed, 14 insertions, 0 deletions

diff --git a/clang/lib/Frontend/DependencyFile.cpp b/clang/lib/Frontend/DependencyFile.cpp
index 561eb9c4a31..5ad1e97a8ff 100644
--- a/clang/lib/Frontend/DependencyFile.cpp
+++ b/clang/lib/Frontend/DependencyFile.cpp
@@ -185,6 +185,10 @@ public:
   void FileChanged(SourceLocation Loc, FileChangeReason Reason,
                    SrcMgr::CharacteristicKind FileType,
                    FileID PrevFID) override;
+
+  void FileSkipped(const FileEntry &SkippedFile, const Token &FilenameTok,
+                   SrcMgr::CharacteristicKind FileType) override;
+
   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
                           StringRef FileName, bool IsAngled,
                           CharSourceRange FilenameRange, const FileEntry *File,
@@ -291,6 +295,16 @@ void DFGImpl::FileChanged(SourceLocation Loc,
   AddFilename(llvm::sys::path::remove_leading_dotslash(Filename));
 }
 
+void DFGImpl::FileSkipped(const FileEntry &SkippedFile,
+                          const Token &FilenameTok,
+                          SrcMgr::CharacteristicKind FileType) {
+  StringRef Filename = SkippedFile.getName();
+  if (!FileMatchesDepCriteria(Filename.data(), FileType))
+    return;
+
+  AddFilename(llvm::sys::path::remove_leading_dotslash(Filename));
+}
+
 void DFGImpl::InclusionDirective(SourceLocation HashLoc,
                                  const Token &IncludeTok,
                                  StringRef FileName,