[clang] [clang][Preprocessor] Handle the first pp-token in EnterMainSourceFile (PR #145244)

[Shafik Yaghmour via cfe-commits]

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@@ -139,10 +139,9 @@ class TokenLexer {
   void Init(const Token *TokArray, unsigned NumToks, bool DisableMacroExpansion,
             bool OwnsTokens, bool IsReinject);
 
-  /// If the next token lexed will pop this macro off the
-  /// expansion stack, return 2.  If the next unexpanded token is a '(', return
-  /// 1, otherwise return 0.
-  unsigned isNextTokenLParen() const;
+  /// If the next token lexed will pop this macro off the expansion stack,
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shafik wrote:

What is the `(` doing there?

https://github.com/llvm/llvm-project/pull/145244