Detect source location overflow due includes

Summary:
As discussed in http://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html
the overflow of the souce locations (limited to 2^31 chars) can generate all sorts of
weird things (bogus warnings, hangs, crashes, miscompilation and correct compilation).
In debug mode this assert would fail. So it might be a good start, as in PR42301,
to detect the failure and exit with a proper error message.

Reviewers: rsmith, thakis, miyuki

Reviewed By: miyuki

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70183

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/Lex/Preprocessor.cpp b/clang/lib/Lex/Preprocessor.cpp
index 0e9be3923630..a18dc4af4226 100644
--- a/clang/lib/Lex/Preprocessor.cpp
+++ b/clang/lib/Lex/Preprocessor.cpp
@@ -906,6 +906,9 @@ void Preprocessor::Lex(Token &Result) {
     }
   } while (!ReturnedToken);
 
+  if (Result.is(tok::unknown) && TheModuleLoader.HadFatalFailure)
+    return;
+
   if (Result.is(tok::code_completion) && Result.getIdentifierInfo()) {
     // Remember the identifier before code completion token.
     setCodeCompletionIdentifierInfo(Result.getIdentifierInfo());
@@ -1200,6 +1203,13 @@ bool Preprocessor::LexAfterModuleImport(Token &Result) {
       Suffix[0].setAnnotationValue(Action.ModuleForHeader);
       // FIXME: Call the moduleImport callback?
       break;
+    case ImportAction::Failure:
+      assert(TheModuleLoader.HadFatalFailure &&
+             "This should be an early exit only to a fatal error");
+      Result.setKind(tok::eof);
+      CurLexer->cutOffLexing();
+      EnterTokens(Suffix);
+      return true;
     }
 
     EnterTokens(Suffix);