Allow resetting of NumCreatedFIDsForFileID

[v.g.vassilev]

Summary

Our internal clients implement parsing cache based on FileID. In order for the Preprocessor to reenter the cached FileID it needs to reset its NumCreatedFIDsForFileID.

Alternatively we can simply remove the assert ;)

[v.g.vassilev]

Add parens.

include/clang/Basic/SourceManager.h

unsigned getNumCreatedFIDsForFileID(FileID FID) const {
     if (Invalid || !Entry.isFile())
       return 0;
 
     return Entry.getFile().NumCreatedFIDs;
   }
 
   /// Set the number of FileIDs (files and macros) that were created
   /// during preprocessing of \p FID, including it.
-  void setNumCreatedFIDsForFileID(FileID FID, unsigned NumFIDs) const {
+  void setNumCreatedFIDsForFileID(FileID FID, unsigned NumFIDs,
+                                  bool Force = false) const {
     bool Invalid = false;
     const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
     if (Invalid || !Entry.isFile())
       return;
 
-    assert(Entry.getFile().NumCreatedFIDs == 0 && "Already set!");
+    assert((Force || Entry.getFile().NumCreatedFIDs == 0) && "Already set!");
     const_cast<SrcMgr::FileInfo &>(Entry.getFile()).NumCreatedFIDs = NumFIDs;
   }
 
   //===--------------------------------------------------------------------===//
   // SourceLocation manipulation methods.
   //===--------------------------------------------------------------------===//
 
   /// Return the FileID for a SourceLocation.