[lex] Provide a valid token when __has_include is found outside of a pp directive

ExpandBuiltinMacro would strip the identifier and downstream users crash
when they encounter an identifier token with nullptr identifier info.

Found by afl-fuzz.

llvm-svn: 233497

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index f2baddd0b83..3ceba05401a 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -1073,6 +1073,9 @@ static bool EvaluateHasIncludeCommon(Token &Tok,
   // These expressions are only allowed within a preprocessor directive.
   if (!PP.isParsingIfOrElifDirective()) {
     PP.Diag(LParenLoc, diag::err_pp_directive_required) << II->getName();
+    // Return a valid identifier token.
+    assert(Tok.is(tok::identifier));
+    Tok.setIdentifierInfo(II);
     return false;
   }