[NFC][Clang][Preprocessor] Refine the implementation of isNextPPTokenOneOf (#145546)

This PR follow the
suggestion(#143898 (comment))
to refine the implementation of `Preprocessor::isNextPPToken`, also use
C++ fold expression to refine `Token::isOneOf`. We don't need `bool
isOneOf(tok::TokenKind K1, tok::TokenKind K2) const` anymore.

In order to reduce the impact, specificed `TokenKind` is still passed to
`Token::isOneOf` and `Preprocessor::isNextPPTokenOneOf` as function
parameters.

---------

Signed-off-by: yronglin <[email protected]>

Author: yronglin

clang/include/clang/Lex/Preprocessor.h

@@ -2304,7 +2304,9 @@ class Preprocessor {
 
   /// Check whether the next pp-token is one of the specificed token kind. this
   /// method should have no observable side-effect on the lexed tokens.
-  template <tok::TokenKind K, tok::TokenKind... Ks> bool isNextPPTokenOneOf() {
+  template <typename... Ts> bool isNextPPTokenOneOf(Ts... Ks) {
+    static_assert(sizeof...(Ts) > 0,
+                  "requires at least one tok::TokenKind specified");
     // Do some quick tests for rejection cases.
     std::optional<Token> Val;
     if (CurLexer)
@@ -2335,7 +2337,7 @@ class Preprocessor {
 
     // Okay, we found the token and return.  Otherwise we found the end of the
     // translation unit.
-    return Val->is(K) || (... || Val->is(Ks));
+    return Val->isOneOf(Ks...);
   }
 
 private:

clang/include/clang/Lex/Token.h

@@ -101,11 +101,10 @@ class Token {
   /// "if (Tok.is(tok::l_brace)) {...}".
   bool is(tok::TokenKind K) const { return Kind == K; }
   bool isNot(tok::TokenKind K) const { return Kind != K; }
-  bool isOneOf(tok::TokenKind K1, tok::TokenKind K2) const {
-    return is(K1) || is(K2);
-  }
-  template <typename... Ts> bool isOneOf(tok::TokenKind K1, Ts... Ks) const {
-    return is(K1) || isOneOf(Ks...);
+  template <typename... Ts> bool isOneOf(Ts... Ks) const {
+    static_assert(sizeof...(Ts) > 0,
+                  "requires at least one tok::TokenKind specified");
+    return (is(Ks) || ...);
   }
 
   /// Return true if this is a raw identifier (when lexing

clang/lib/Lex/PPDirectives.cpp

@@ -183,9 +183,9 @@ static bool isReservedCXXAttributeName(Preprocessor &PP, IdentifierInfo *II) {
     AttributeCommonInfo::AttrArgsInfo AttrArgsInfo =
         AttributeCommonInfo::getCXX11AttrArgsInfo(II);
     if (AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Required)
-      return PP.isNextPPTokenOneOf<tok::l_paren>();
+      return PP.isNextPPTokenOneOf(tok::l_paren);
 
-    return !PP.isNextPPTokenOneOf<tok::l_paren>() ||
+    return !PP.isNextPPTokenOneOf(tok::l_paren) ||
            AttrArgsInfo == AttributeCommonInfo::AttrArgsInfo::Optional;
   }
   return false;

clang/lib/Lex/Preprocessor.cpp

@@ -813,14 +813,14 @@ bool Preprocessor::HandleIdentifier(Token &Identifier) {
       if (!Identifier.isExpandDisabled() && MI->isEnabled()) {
         // C99 6.10.3p10: If the preprocessing token immediately after the
         // macro name isn't a '(', this macro should not be expanded.
-        if (!MI->isFunctionLike() || isNextPPTokenOneOf<tok::l_paren>())
+        if (!MI->isFunctionLike() || isNextPPTokenOneOf(tok::l_paren))
           return HandleMacroExpandedIdentifier(Identifier, MD);
       } else {
         // C99 6.10.3.4p2 says that a disabled macro may never again be
         // expanded, even if it's in a context where it could be expanded in the
         // future.
         Identifier.setFlag(Token::DisableExpand);
-        if (MI->isObjectLike() || isNextPPTokenOneOf<tok::l_paren>())
+        if (MI->isObjectLike() || isNextPPTokenOneOf(tok::l_paren))
           Diag(Identifier, diag::pp_disabled_macro_expansion);
       }
     }