If PCH refers to a file that doesn't exist anymore, emit a nice error

like:
fatal error: could not find file '1.h' referenced by PCH file
instead of aborting with an assertion failure, PR4219

llvm-svn: 73371

1 files changed, 10 insertions, 3 deletions

diff --git a/clang/lib/Frontend/PCHReader.cpp b/clang/lib/Frontend/PCHReader.cpp
index 87fc8394c8d..8ea917c3e34 100644
--- a/clang/lib/Frontend/PCHReader.cpp
+++ b/clang/lib/Frontend/PCHReader.cpp
@@ -804,9 +804,16 @@ PCHReader::PCHReadResult PCHReader::ReadSLocEntryRecord(unsigned ID) {
     return Failure;
 
   case pch::SM_SLOC_FILE_ENTRY: {
-    const FileEntry *File 
-      = PP.getFileManager().getFile(BlobStart, BlobStart + BlobLen);
-    // FIXME: Error recovery if file cannot be found.
+    const FileEntry *File = PP.getFileManager().getFile(BlobStart,
+                                                        BlobStart + BlobLen);
+    if (File == 0) {
+      std::string ErrorStr = "could not find file '";
+      ErrorStr.append(BlobStart, BlobLen);
+      ErrorStr += "' referenced by PCH file";
+      Error(ErrorStr.c_str());
+      return Failure;
+    }
+    
     FileID FID = SourceMgr.createFileID(File,
                                 SourceLocation::getFromRawEncoding(Record[1]),
                                        (SrcMgr::CharacteristicKind)Record[2],