fix a bug Steve noticed, where a #import of the main file itself would fail.

llvm-svn: 44178

clang/Lex/Preprocessor.cpp

@@ -416,7 +416,12 @@ void Preprocessor::EnterMainSourceFile(unsigned MainFileID) {
   // Enter the main file source buffer.
   EnterSourceFile(MainFileID, 0);
   
-  
+  // Tell the header info that the main file was entered.  If the file is later
+  // #imported, it won't be re-entered.
+  if (const FileEntry *FE = 
+        SourceMgr.getFileEntryForLoc(SourceLocation::getFileLoc(MainFileID, 0)))
+    HeaderInfo.IncrementIncludeCount(FE);
+    
   std::vector<char> PrologFile;
   PrologFile.reserve(4080);
   

clang/test/Preprocessor/import_self.c

@@ -0,0 +1,7 @@
+// RUN: clang -E -I. %s | grep BODY_OF_FILE | wc -l | grep 1
+
+// This #import should have no effect, as we're importing the current file.
+#import <import_self.c>
+
+BODY_OF_FILE
+