Scanner hack.

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 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

@@ -322,6 +322,14 @@ namespace TokenTraits
 			tok == Token::Default || tok == Token::For || tok == Token::Break || tok == Token::Continue || tok == Token::Leave ||
 			tok == Token::TrueLiteral || tok == Token::FalseLiteral || tok == Token::HexStringLiteral || tok == Token::Hex;
 	}
+	constexpr bool isExperimentalSolidityKeyword(Token tok)
+	{
+		return tok == Token::Assembly || tok == Token::Contract || tok == Token::External || tok == Token::Fallback;
+	}
+	constexpr bool isExperimentalSolidityOnlyKeyword(Token)
+	{
+		return false;
+	}
 
 	bool isYulKeyword(std::string const& _literal);
 

libsolidity/interface/CompilerStack.h

@@ -503,6 +503,7 @@ private:
 	std::map<std::string, util::h160> m_libraries;
 	ImportRemapper m_importRemapper;
 	std::map<std::string const, Source> m_sources;
+	std::optional<int64_t> m_maxAstId;
 	std::vector<std::string> m_unhandledSMTLib2Queries;
 	std::map<util::h256, std::string> m_smtlib2Responses;
 	std::shared_ptr<GlobalContext> m_globalContext;

libsolidity/parsing/Parser.cpp

@@ -100,6 +100,9 @@ ASTPointer<SourceUnit> Parser::parse(CharStream& _charStream)
 		while (m_scanner->currentToken() == Token::Pragma)
 			nodes.push_back(parsePragmaDirective(false));
 
+		if (m_experimentalSolidityEnabledInCurrentSourceUnit)
+			m_scanner->setScannerMode(ScannerKind::ExperimentalSolidity);
+
 		while (m_scanner->currentToken() != Token::EOS)
 		{
 			switch (m_scanner->currentToken())

libsolidity/parsing/Parser.h

@@ -197,6 +197,8 @@ private:
 
 	/// Returns the next AST node ID
 	int64_t nextID() { return ++m_currentNodeID; }
+	/// Returns the maximal AST node ID assigned so far
+	int64_t maxID() const { return m_currentNodeID; }
 
 	std::pair<LookAheadInfo, IndexAccessedPath> tryParseIndexAccessedPath();
 	/// Performs limited look-ahead to distinguish between variable declaration and expression statement.