Build ASTs before relexing the file. This avoids having comment finding mutate the

preprocessor state, causing bogus diagnostics when the file is parsed for real.  This
implements Misc/diag-checker.c.  Thanks to Ted for noticing this.

llvm-svn: 41000

clang/Driver/DiagChecker.cpp

@@ -216,13 +216,13 @@ static bool CheckResults(Preprocessor &PP,
 
 /// CheckDiagnostics - Implement the -parse-ast-check diagnostic verifier.
 bool clang::CheckDiagnostics(Preprocessor &PP, unsigned MainFileID) {
+  // Parse the specified input file.
+  BuildASTs(PP, MainFileID, false);
+
   // Gather the set of expected diagnostics.
   DiagList ExpectedErrors, ExpectedWarnings;
   FindExpectedDiags(PP, MainFileID, ExpectedErrors, ExpectedWarnings);
   
-  // Parse the specified input file.
-  BuildASTs(PP, MainFileID, false);
-
   // Check that the expected diagnostics occurred.
   return CheckResults(PP, ExpectedErrors, ExpectedWarnings);
 }

clang/test/Misc/diag-checker.c

@@ -0,0 +1,5 @@
+// RUN: clang -parse-ast-check %s
+
+#include <stdio.h>
+
+void foo(FILE *FP) {}