Fix CheckEndOfDirective to diagnose lines that contain macros that expand to

zero tokens.  This fixes PR2045, thanks to Neil for finding another 
incredibly subtle corner case :)



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@47203 91177308-0d34-0410-b5e6-96231b3b80d8

Lex/Preprocessor.cpp

@@ -1498,11 +1498,14 @@ void Preprocessor::ReadMacroName(Token &MacroNameTok, char isDefineUndef) {
 /// not, emit a diagnostic and consume up until the eom.
 void Preprocessor::CheckEndOfDirective(const char *DirType) {
   Token Tmp;
-  Lex(Tmp);
+  // Lex unexpanded tokens: macros might expand to zero tokens, causing us to
+  // miss diagnosing invalid lines.
+  LexUnexpandedToken(Tmp);
+  
   // There should be no tokens after the directive, but we allow them as an
   // extension.
   while (Tmp.is(tok::comment))  // Skip comments in -C mode.
-    Lex(Tmp);
+    LexUnexpandedToken(Tmp);
   
   if (Tmp.isNot(tok::eom)) {
     Diag(Tmp, diag::ext_pp_extra_tokens_at_eol, DirType);

Sema/SemaDecl.cpp

@@ -1032,8 +1032,7 @@ Sema::DeclTy *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Declarator &D) {
     }
   }
   Decl *decl = static_cast<Decl*>(ActOnDeclarator(GlobalScope, D, 0));
-  FunctionDecl *FD = dyn_cast<FunctionDecl>(decl);
-  assert(FD != 0 && "ActOnDeclarator() didn't return a FunctionDecl");
+  FunctionDecl *FD = cast<FunctionDecl>(decl);
   CurFunctionDecl = FD;
   
   // Create Decl objects for each parameter, adding them to the FunctionDecl.

test/Preprocessor/undef-error.c

@@ -0,0 +1,5 @@
+// RUN: not clang %s -pedantic-errors -E
+// PR2045
+
+#define b
+#undef a b