[Preamble] Stop circular inclusion of main file when building preamble

If a header file was processed for the second time, we could end up with a
wrong conditional stack and skipped ranges:

In the particular example, if the header guard is evaluated the second time and
it is decided to skip the conditional block, the corresponding "#endif" is
never seen since the preamble does not include it and we end up in the
Tok.is(tok::eof) case with a wrong conditional stack.

Detect the circular inclusion, emit a diagnostic and stop processing the
inclusion.

llvm-svn: 360418

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 0ffad1bc475..712cbb0d0ea 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -1582,7 +1582,7 @@ FileID SourceManager::translateFile(const FileEntry *SourceFile) const {
     if (MainSLoc.isFile()) {
       const ContentCache *MainContentCache
         = MainSLoc.getFile().getContentCache();
-      if (!MainContentCache) {
+      if (!MainContentCache || !MainContentCache->OrigEntry) {
         // Can't do anything
       } else if (MainContentCache->OrigEntry == SourceFile) {
         FirstFID = MainFileID;