Disable _Pragma during HTML macro rewriting to keep from crashing.

The preprocessor's handling of diagnostic push/pops is stateful, so
encountering pragmas during a re-parse causes problems. HTMLRewrite
already filters out normal # directives including #pragma, so it's
clear it's not expected to be interpreting pragmas in this mode.

This fix adds a flag to Preprocessor to explicitly disable pragmas.
The "right" fix might be to separate pragma lexing from pragma
parsing so that we can throw away pragmas like we do preprocessor
directives, but right now it's important to get the fix in.

Note that this has nothing to do with the "hack" of re-using the
input preprocessor in HTMLRewrite. Even if we someday copy the
preprocessor instead of re-using it, the copy would (and should) include
the diagnostic level tables and have the same problems.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158214 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 1 deletions

diff --git a/lib/Rewrite/HTMLRewrite.cpp b/lib/Rewrite/HTMLRewrite.cpp
index dc39dde7ff..e2da26fc80 100644
--- a/lib/Rewrite/HTMLRewrite.cpp
+++ b/lib/Rewrite/HTMLRewrite.cpp
@@ -495,6 +495,11 @@ void html::HighlightMacros(Rewriter &R, FileID FID, const Preprocessor& PP) {
   // Inform the preprocessor that we don't want comments.
   TmpPP.SetCommentRetentionState(false, false);
 
+  // We don't want pragmas either. Although we filtered out #pragma, removing
+  // _Pragma and __pragma is much harder.
+  bool PragmasPreviouslyEnabled = TmpPP.getPragmasEnabled();
+  TmpPP.setPragmasEnabled(false);
+
   // Enter the tokens we just lexed.  This will cause them to be macro expanded
   // but won't enter sub-files (because we removed #'s).
   TmpPP.EnterTokenStream(&TokenStream[0], TokenStream.size(), false, false);
@@ -571,6 +576,7 @@ void html::HighlightMacros(Rewriter &R, FileID FID, const Preprocessor& PP) {
                    "<span class='macro'>", Expansion.c_str());
   }
 
-  // Restore diagnostics object back to its own thing.
+  // Restore the preprocessor's old state.
   TmpPP.setDiagnostics(*OldDiags);
+  TmpPP.setPragmasEnabled(PragmasPreviouslyEnabled);
 }