Introduce experimental analysis basic infrastructure

liblangutil/Scanner.cpp

@@ -1019,15 +1019,28 @@ std::tuple<Token, unsigned, unsigned> Scanner::scanIdentifierOrKeyword()
 	while (isIdentifierPart(m_char) || (m_char == '.' && m_kind == ScannerKind::Yul))
 		addLiteralCharAndAdvance();
 	literal.complete();
+
 	auto const token = TokenTraits::fromIdentifierOrKeyword(m_tokens[NextNext].literal);
-	if (m_kind == ScannerKind::Yul)
+	switch (m_kind)
 	{
+	case ScannerKind::Solidity:
+		// Turn experimental Solidity keywords that are not keywords in legacy Solidity into identifiers.
+		if (TokenTraits::isExperimentalSolidityOnlyKeyword(std::get<0>(token)))
+			return std::make_tuple(Token::Identifier, 0, 0);
+		break;
+	case ScannerKind::Yul:
 		// Turn Solidity identifier into a Yul keyword
 		if (m_tokens[NextNext].literal == "leave")
 			return std::make_tuple(Token::Leave, 0, 0);
 		// Turn non-Yul keywords into identifiers.
 		if (!TokenTraits::isYulKeyword(std::get<0>(token)))
 			return std::make_tuple(Token::Identifier, 0, 0);
+		break;
+	case ScannerKind::ExperimentalSolidity:
+		// Turn legacy Solidity keywords that are not keywords in experimental Solidity into identifiers.
+		if (!TokenTraits::isExperimentalSolidityKeyword(std::get<0>(token)))
+			return std::make_tuple(Token::Identifier, 0, 0);
+		break;
 	}
 	return token;
 }

liblangutil/Scanner.h

@@ -69,7 +69,8 @@ class ParserRecorder;
 enum class ScannerKind
 {
 	Solidity,
-	Yul
+	Yul,
+	ExperimentalSolidity
 };
 
 enum class ScannerError

liblangutil/Token.h

@@ -268,6 +268,8 @@ namespace solidity::langutil
 	/* Yul-specific tokens, but not keywords. */                       \
 	T(Leave, "leave", 0)                                               \
 	\
+	T(NonExperimentalEnd, nullptr, 0) /* used as non-experimental enum end marker */ \
+	T(ExperimentalEnd, nullptr, 0) /* used as experimental enum end marker */ \
 	/* Illegal token - not able to scan. */                            \
 	T(Illegal, "ILLEGAL", 0)                                           \
 	\
@@ -323,6 +325,39 @@ namespace TokenTraits
 			tok == Token::TrueLiteral || tok == Token::FalseLiteral || tok == Token::HexStringLiteral || tok == Token::Hex;
 	}
 
+	constexpr bool isExperimentalSolidityKeyword(Token token)
+	{
+		return
+			token == Token::Assembly ||
+			token == Token::Contract ||
+			token == Token::External ||
+			token == Token::Fallback ||
+			token == Token::Pragma ||
+			token == Token::Import ||
+			token == Token::As ||
+			token == Token::Function ||
+			token == Token::Let ||
+			token == Token::Return ||
+			token == Token::Type ||
+			token == Token::If ||
+			token == Token::Else ||
+			token == Token::Do ||
+			token == Token::While ||
+			token == Token::For ||
+			token == Token::Continue ||
+			token == Token::Break;
+			// TODO: see isExperimentalSolidityKeyword below
+			// || (token > Token::NonExperimentalEnd && token < Token::ExperimentalEnd);
+	}
+
+	constexpr bool isExperimentalSolidityOnlyKeyword(Token)
+	{
+		// TODO: use token > Token::NonExperimentalEnd && token < Token::ExperimentalEnd
+		// as soon as other experimental tokens are added. For now the comparison generates
+		// a warning from clang because it is always false.
+		return false;
+	}
+
 	bool isYulKeyword(std::string const& _literal);
 
 	Token AssignmentToBinaryOp(Token op);