tmp

liblangutil/Token.h

@@ -330,7 +330,7 @@ namespace TokenTraits
 	constexpr bool isExperimentalSolidityKeyword(Token tok)
 	{
 		return tok == Token::Assembly || tok == Token::Contract || tok == Token::External || tok == Token::Fallback ||
-			tok == Token::Pragma || tok == Token::Import || tok == Token::As || tok == Token::Function ||
+			tok == Token::Pragma || tok == Token::Import || tok == Token::As || tok == Token::Function || tok == Token::Let ||
 			(tok >= Token::Word && tok < Token::ExperimentalEnd);
 	}
 	constexpr bool isExperimentalSolidityOnlyKeyword(Token tok)

libsolidity/CMakeLists.txt

@@ -74,6 +74,8 @@ set(sources
 	ast/Types.h
 	ast/TypeProvider.cpp
 	ast/TypeProvider.h
+	ast/experimental/TypeSystem.cpp
+	ast/experimental/TypeSystem.h
 	codegen/ABIFunctions.cpp
 	codegen/ABIFunctions.h
 	codegen/ArrayUtils.cpp

libsolidity/analysis/experimental/Analysis.cpp

@@ -18,14 +18,27 @@
 #include <libsolidity/analysis/experimental/Analysis.h>
 
 #include <libsolidity/analysis/experimental/SyntaxRestrictor.h>
+#include <libsolidity/analysis/experimental/TypeInference.h>
 
+using namespace std;
 using namespace solidity::langutil;
 using namespace solidity::frontend::experimental;
 
-bool Analysis::check(ASTNode const& _node)
+Analysis::Analysis(langutil::ErrorReporter& _errorReporter, uint64_t _maxAstId):
+	m_errorReporter(_errorReporter),
+	m_maxAstId(_maxAstId)
+{
+}
+
+bool Analysis::check(vector<shared_ptr<SourceUnit const>> const& _sourceUnits)
 {
 	SyntaxRestrictor syntaxRestrictor{m_errorReporter};
-	if (!syntaxRestrictor.check(_node))
+	for (auto source: _sourceUnits)
+		if (!syntaxRestrictor.check(*source))
+			return false;
+	TypeInference typeInference{m_errorReporter};
+	for (auto source: _sourceUnits)
+		if (!typeInference.analyze(*source))
 			return false;
 	return true;
 }

libsolidity/analysis/experimental/Analysis.h

@@ -18,10 +18,12 @@
 #pragma once
 
 #include <cstdint>
+#include <memory>
+#include <vector>
 
 namespace solidity::frontend
 {
-class ASTNode;
+class SourceUnit;
 }
 
 namespace solidity::langutil
@@ -35,11 +37,8 @@ namespace solidity::frontend::experimental
 class Analysis
 {
 public:
-	Analysis(langutil::ErrorReporter& _errorReporter, uint64_t _maxAstId):
-	m_errorReporter(_errorReporter),
-	m_maxAstId(_maxAstId)
-	{}
-	bool check(ASTNode const& _ast);
+	Analysis(langutil::ErrorReporter& _errorReporter, uint64_t _maxAstId);
+	bool check(std::vector<std::shared_ptr<SourceUnit const>> const& _sourceUnits);
 private:
 	langutil::ErrorReporter& m_errorReporter;
 	uint64_t m_maxAstId = 0;

libsolidity/analysis/experimental/SyntaxRestrictor.cpp

@@ -49,10 +49,10 @@ bool SyntaxRestrictor::visit(FunctionDefinition const& _functionDefinition)
 {
 	if (!_functionDefinition.isImplemented())
 		m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Functions must be implemented.");
-	if (!_functionDefinition.parameterList().parameters().empty())
-		m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Function may not have arguments.");
-	if (_functionDefinition.returnParameterList() && !_functionDefinition.returnParameterList()->parameters().empty())
-		m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Function may not have return variables.");
+	if (!_functionDefinition.modifiers().empty())
+		m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Function may not have modifiers.");
+	if (_functionDefinition.overrides())
+		m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Function may not have override specifiers.");
 	if (_functionDefinition.isFree())
 	{
 		if (_functionDefinition.stateMutability() != StateMutability::NonPayable)
@@ -69,9 +69,7 @@ bool SyntaxRestrictor::visit(FunctionDefinition const& _functionDefinition)
 			m_errorReporter.syntaxError(0000_error, _functionDefinition.location(), "Only fallback functions are supported in contracts.");
 	}
 
-	_functionDefinition.body().accept(*this);
-
-	return false;
+	return true;
 }
 
 bool SyntaxRestrictor::visit(VariableDeclarationStatement const& _variableDeclarationStatement)

libsolidity/analysis/experimental/SyntaxRestrictor.h

@@ -42,12 +42,15 @@ private:
 	bool visit(ImportDirective const&) override { return true; }
 	bool visit(ContractDefinition const& _contractDefinition) override;
 	bool visit(FunctionDefinition const& _functionDefinition) override;
+	bool visit(ExpressionStatement const&) override { return true; }
+	bool visit(Assignment const&) override { return true; }
 	bool visit(Block const&) override { return true; }
 	bool visit(InlineAssembly const&) override { return true; }
 	bool visit(Identifier const&) override { return true; }
 	bool visit(VariableDeclarationStatement const&) override;
 	bool visit(VariableDeclaration const&) override;
 	bool visit(ElementaryTypeName const&) override { return true; }
+	bool visit(ParameterList const&) override { return true; }
 
 	langutil::ErrorReporter& m_errorReporter;
 };

libsolidity/analysis/experimental/TypeInference.cpp

@@ -20,18 +20,119 @@
 #include <libsolidity/analysis/experimental/TypeInference.h>
 #include <liblangutil/Exceptions.h>
 
+#include <libyul/AsmAnalysis.h>
+#include <libyul/AsmAnalysisInfo.h>
+#include <libyul/AST.h>
+
+using namespace std;
 using namespace solidity::frontend;
 using namespace solidity::frontend::experimental;
 using namespace solidity::langutil;
 
+bool TypeInference::analyze(SourceUnit const& _sourceUnit)
+{
+	_sourceUnit.accept(*this);
+	return !m_errorReporter.hasErrors();
+}
+
+bool TypeInference::visit(FunctionDefinition const& _functionDefinition)
+{
+	ScopedSaveAndRestore env{m_env, {}};
+	_functionDefinition.parameterList().accept(*this);
+	if (_functionDefinition.returnParameterList())
+		_functionDefinition.returnParameterList()->accept(*this);
+
+	_functionDefinition.body().accept(*this);
+
+	return false;
+}
+
+bool TypeInference::visit(ParameterList const&)
+{
+	return true;
+}
+
 bool TypeInference::visitNode(ASTNode const& _node)
 {
 	m_errorReporter.typeError(0000_error, _node.location(), "Unsupported AST node during type inference.");
 	return false;
 }
 
-bool TypeInference::visit(VariableDeclaration const&)
+experimental::Type TypeInference::fromTypeName(TypeName const& _typeName)
 {
-//	m_env.assignType(&_varialeDeclaration, m_env.lookupType(_varialeDeclaration.typeName()));
+	if (auto const* elementaryTypeName = dynamic_cast<ElementaryTypeName const*>(&_typeName))
+	{
+		switch(elementaryTypeName->typeName().token())
+		{
+		case Token::Word:
+			return WordType{};
+		default:
+			m_errorReporter.typeError(0000_error, _typeName.location(), "Only elementary types are supported.");
+			break;
+		}
+	}
+	else
+		m_errorReporter.typeError(0000_error, _typeName.location(), "Only elementary types are supported.");
+	return m_env.freshFreeType();
+
+}
+
+bool TypeInference::visit(InlineAssembly const& _inlineAssembly)
+{
+	// External references have already been resolved in a prior stage and stored in the annotation.
+	// We run the resolve step again regardless.
+	yul::ExternalIdentifierAccess::Resolver identifierAccess = [&](
+		yul::Identifier const& _identifier,
+		yul::IdentifierContext _context,
+		bool
+	) -> bool
+	{
+		if (_context == yul::IdentifierContext::NonExternal)
+		{
+			// Hack until we can disallow any shadowing: If we found an internal reference,
+			// clear the external references, so that codegen does not use it.
+			_inlineAssembly.annotation().externalReferences.erase(& _identifier);
+			return false;
+		}
+		auto ref = _inlineAssembly.annotation().externalReferences.find(&_identifier);
+		if (ref == _inlineAssembly.annotation().externalReferences.end())
+			return false;
+		InlineAssemblyAnnotation::ExternalIdentifierInfo& identifierInfo = ref->second;
+		Declaration const* declaration = identifierInfo.declaration;
+		solAssert(!!declaration, "");
+
+		m_env.assignType(m_typeSystem, declaration, WordType{});
+		identifierInfo.valueSize = 1;
+		return true;
+	};
+	solAssert(!_inlineAssembly.annotation().analysisInfo, "");
+	_inlineAssembly.annotation().analysisInfo = make_shared<yul::AsmAnalysisInfo>();
+	yul::AsmAnalyzer analyzer(
+		*_inlineAssembly.annotation().analysisInfo,
+		m_errorReporter,
+		_inlineAssembly.dialect(),
+		identifierAccess
+	);
+	if (!analyzer.analyze(_inlineAssembly.operations()))
+		solAssert(m_errorReporter.hasErrors());
 	return false;
 }
+
+bool TypeInference::visit(VariableDeclaration const& _variableDeclaration)
+{
+	Type type = _variableDeclaration.hasTypeName() ? fromTypeName(_variableDeclaration.typeName()) : m_typeSystem.freshTypeVariable();
+	m_env.assignType(m_typeSystem, &_variableDeclaration, type);
+	return false;
+}
+
+bool TypeInference::visit(Assignment const& _assignment)
+{
+	(void)_assignment;
+	return true;
+}
+
+bool TypeInference::visit(Identifier const& _identifier)
+{
+	(void)_identifier;
+	return true;
+}

libsolidity/analysis/experimental/TypeInference.h

@@ -18,6 +18,7 @@
 #pragma once
 
 #include <libsolidity/ast/ASTVisitor.h>
+#include <libsolidity/ast/experimental/TypeSystem.h>
 
 #include <liblangutil/ErrorReporter.h>
 
@@ -26,84 +27,32 @@
 namespace solidity::frontend::experimental
 {
 
-class GlobalTypeContext;
-
-struct SumType;
-struct TupleType;
-struct FunctionType;
-struct WordType;
-struct UserDefinedType;
-struct TypeVariable;
-struct FreeType;
-
-using Type = std::variant<SumType, TupleType, FunctionType, WordType, UserDefinedType, TypeVariable, FreeType>;
-
-struct SumType
-{
-	std::vector<Type const*> alternatives;
-};
-
-struct TupleType
-{
-	std::vector<Type const*> components;
-};
-
-struct FunctionType
-{
-	Type const* codomain = nullptr;
-	Type const* domain = nullptr;
-};
-
-struct WordType
-{
-};
-
-struct UserDefinedType
-{
-	Declaration const* declaration = nullptr;
-	std::vector<Type const*> arguments;
-};
-
-struct TypeVariable
-{
-	uint64_t index = 0;
-};
-
-struct FreeType
-{
-	uint64_t index = 0;
-};
-
-Type unify(Type _a, Type _b)
-{
-	
-}
-
-class TypeEnvironment
-{
-public:
-	TypeEnvironment() {}
-	void assignType(Declaration const* _declaration, Type _typeAssignment)
-	{
-		m_types.emplace(std::piecewise_construct, std::forward_as_tuple(_declaration), std::forward_as_tuple(std::move(_typeAssignment)));
-	}
-private:
-	uint64_t m_numTypeVariables = 0;
-	std::map<Declaration const*, Type> m_types;
-};
-
 class TypeInference: public ASTConstVisitor
 {
 public:
 	TypeInference(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
+
+	bool analyze(SourceUnit const& _sourceUnit);
 private:
 	bool visit(Block const&) override { return true; }
 	bool visit(VariableDeclarationStatement const&) override { return true; }
 	bool visit(VariableDeclaration const& _variableDeclaration) override;
 
+	bool visit(FunctionDefinition const& _functionDefinition) override;
+	bool visit(ParameterList const& _parameterList) override;
+	bool visit(SourceUnit const&) override { return true; }
+	bool visit(ContractDefinition const&) override { return true; }
+	bool visit(InlineAssembly const& _inlineAssembly) override;
+	bool visit(PragmaDirective const&) override { return false; }
+
+	bool visit(ExpressionStatement const&) override { return true; }
+	bool visit(Assignment const&) override;
+	bool visit(Identifier const&) override;
+
 	bool visitNode(ASTNode const& _node) override;
 
-private:
+	Type fromTypeName(TypeName const& _typeName);
+	TypeSystem m_typeSystem;
 	langutil::ErrorReporter& m_errorReporter;
 	TypeEnvironment m_env;
 };

libsolidity/ast/AST.h

@@ -1077,13 +1077,15 @@ public:
 		m_overrides(std::move(_overrides)),
 		m_location(_referenceLocation)
 	{
-		solAssert(m_typeName, "");
+		// TODO: consider still asserting unless we are in experimental solidity.
+		// solAssert(m_typeName, "");
 	}
 
 
 	void accept(ASTVisitor& _visitor) override;
 	void accept(ASTConstVisitor& _visitor) const override;
 
+	bool hasTypeName() const { return m_typeName != nullptr; }
 	TypeName const& typeName() const { return *m_typeName; }
 	ASTPointer<Expression> const& value() const { return m_value; }
 

libsolidity/ast/experimental/TypeSystem.cpp

@@ -0,0 +1,64 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+
+#include <libsolidity/ast/experimental/TypeSystem.h>
+#include <liblangutil/Exceptions.h>
+
+using namespace std;
+using namespace solidity::frontend;
+using namespace solidity::frontend::experimental;
+
+void TypeEnvironment::assignType(TypeSystem& _typeSystem, Declaration const* _declaration, Type _typeAssignment)
+{
+	auto&& [type, newlyInserted] = m_types.emplace(std::piecewise_construct, std::forward_as_tuple(_declaration), std::forward_as_tuple(std::move(_typeAssignment)));
+	if (!newlyInserted)
+	{
+		unify(_typeSystem, type->second, _typeAssignment);
+	}
+}
+Type TypeEnvironment::lookup(TypeSystem& _typeSystem, Declaration const* _declaration)
+{
+	if (m_types.count(_declaration))
+		return m_types[_declaration];
+	Type result = _typeSystem.freshTypeVariable();
+	m_types.emplace(std::piecewise_construct, std::forward_as_tuple(_declaration), std::forward_as_tuple(result));
+	return result;
+}
+Type TypeEnvironment::freshFreeType()
+{
+	return FreeType{m_numFreeTypes++};
+}
+
+
+void TypeEnvironment::unify(TypeSystem& _context, Type _a, Type _b)
+{
+	_a = _context.resolve(_a);
+	_b = _context.resolve(_b);
+	if (auto* varA = get_if<TypeVariable>(&_a))
+		_context.instantiate(*varA, _b);
+	else if (holds_alternative<WordType>(_a))
+	{
+		if (holds_alternative<WordType>(_b))
+			return;
+		else
+			solAssert(false, "unification failed");
+	}
+
+	solAssert(false, fmt::format("cannot unify {} and {}", typeToString(_a), typeToString(_b)));
+}

libsolidity/ast/experimental/TypeSystem.h

@@ -0,0 +1,167 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+#pragma once
+
+#include <liblangutil/Exceptions.h>
+
+#include <fmt/format.h>
+
+#include <optional>
+#include <string>
+#include <variant>
+#include <vector>
+
+namespace solidity::frontend
+{
+class Declaration;
+}
+
+namespace solidity::frontend::experimental
+{
+
+class TypeSystem;
+
+struct SumType;
+struct TupleType;
+struct FunctionType;
+struct WordType;
+struct UserDefinedType;
+struct TypeVariable;
+struct FreeType;
+
+using Type = std::variant<SumType, TupleType, FunctionType, WordType, UserDefinedType, TypeVariable, FreeType>;
+
+struct SumType
+{
+	std::vector<Type const*> alternatives;
+	std::string toString() const
+	{
+		return "sum";
+	}
+};
+
+struct TupleType
+{
+	std::vector<Type const*> components;
+	std::string toString() const
+	{
+		return "tuple";
+	}
+};
+
+struct FunctionType
+{
+	Type const* codomain = nullptr;
+	Type const* domain = nullptr;
+	std::string toString() const
+	{
+		return "fun";
+	}
+};
+
+struct WordType
+{
+	std::string toString() const
+	{
+		return "word";
+	}
+};
+
+struct UserDefinedType
+{
+	Declaration const* declaration = nullptr;
+	std::vector<Type const*> arguments;
+	std::string toString() const
+	{
+		return "user_defined_type";
+	}
+};
+
+struct TypeVariable
+{
+	std::string toString() const
+	{
+		return fmt::format("var<{}>", m_index);
+	}
+private:
+	uint64_t index() const { return m_index; }
+	friend class TypeSystem;
+	uint64_t m_index = 0;
+	TypeVariable(uint64_t _index): m_index(_index) {}
+};
+
+struct FreeType
+{
+	uint64_t index = 0;
+	std::string toString() const
+	{
+		return fmt::format("free<{}>", index);
+	}
+};
+
+inline std::string typeToString(Type const& _type)
+{
+	return std::visit([](auto _type) { return _type.toString(); }, _type);
+}
+
+class TypeEnvironment
+{
+public:
+	void assignType(TypeSystem& _typeSystem, Declaration const* _declaration, Type _typeAssignment);
+	Type lookup(TypeSystem& _typeSystem, Declaration const* _declaration);
+	Type freshFreeType();
+	void unify(TypeSystem& _typeSystem, Type _a, Type _b);
+private:
+	uint64_t m_numFreeTypes = 0;
+	std::map<Declaration const*, Type> m_types;
+};
+
+
+class TypeSystem
+{
+public:
+	TypeSystem() {}
+	TypeSystem(TypeSystem const&) = delete;
+	TypeSystem const& operator=(TypeSystem const&) = delete;
+	Type freshTypeVariable()
+	{
+		uint64_t index = m_typeVariables.size();
+		m_typeVariables.emplace_back(std::nullopt);
+		return TypeVariable(index);
+	}
+	void instantiate(TypeVariable _variable, Type _type)
+	{
+		solAssert(_variable.index() < m_typeVariables.size());
+		solAssert(!m_typeVariables.at(_variable.index()).has_value());
+		m_typeVariables[_variable.index()] = _type;
+	}
+	Type resolve(Type _type)
+	{
+		Type result = _type;
+		while(auto const* var = std::get_if<TypeVariable>(&result))
+			if (auto value = m_typeVariables.at(var->index()))
+				result = *value;
+			else
+				break;
+		return result;
+	}
+private:
+	std::vector<std::optional<Type>> m_typeVariables;
+};
+
+}

libsolidity/codegen/experimental/IRGenerator.cpp

@@ -18,6 +18,8 @@
 
 #include <libsolidity/codegen/experimental/IRGenerator.h>
 
+#include <libsolidity/codegen/experimental/IRGeneratorForStatements.h>
+
 #include <libsolidity/codegen/ir/Common.h>
 
 #include <libyul/YulStack.h>
@@ -87,74 +89,9 @@ string IRGenerator::generate(FunctionDefinition const& _function) const
 	code << "function " << IRNames::function(_function) << "() {\n";
 	for (auto _statement: _function.body().statements())
 	{
-		if (auto assembly = dynamic_cast<InlineAssembly const*>(_statement.get()))
-			code << generate(*assembly) << "\n";
-		else
-			solUnimplemented("Unsupported statement type.");
+		IRGeneratorForStatements statementGenerator{m_analysis};
+		code << statementGenerator.generate(*_statement);
 	}
 	code << "}\n";
 	return code.str();
 }
-
-namespace {
-
-struct CopyTranslate: public yul::ASTCopier
-{
-	CopyTranslate(
-		yul::Dialect const& _dialect,
-		map<yul::Identifier const*, void*> _references
-	): m_dialect(_dialect), m_references(std::move(_references)) {}
-
-	using ASTCopier::operator();
-
-	yul::Expression operator()(yul::Identifier const& _identifier) override
-	{
-		// The operator() function is only called in lvalue context. In rvalue context,
-		// only translate(yul::Identifier) is called.
-		if (m_references.count(&_identifier))
-			return translateReference(_identifier);
-		else
-			return ASTCopier::operator()(_identifier);
-	}
-
-	yul::YulString translateIdentifier(yul::YulString _name) override
-	{
-		if (m_dialect.builtin(_name))
-			return _name;
-		else
-			return yul::YulString{"usr$" + _name.str()};
-	}
-
-	yul::Identifier translate(yul::Identifier const& _identifier) override
-	{
-		if (!m_references.count(&_identifier))
-			return ASTCopier::translate(_identifier);
-
-		yul::Expression translated = translateReference(_identifier);
-		solAssert(holds_alternative<yul::Identifier>(translated));
-		return get<yul::Identifier>(std::move(translated));
-	}
-
-private:
-
-	/// Translates a reference to a local variable, potentially including
-	/// a suffix. Might return a literal, which causes this to be invalid in
-	/// lvalue-context.
-	yul::Expression translateReference(yul::Identifier const&)
-	{
-		solUnimplemented("External references in inline assembly not implemented.");
-	}
-
-	yul::Dialect const& m_dialect;
-	map<yul::Identifier const*, void*> m_references;
-};
-
-}
-
-string IRGenerator::generate(InlineAssembly const& _assembly) const
-{
-	CopyTranslate bodyCopier{_assembly.dialect(), {}};
-	yul::Statement modified = bodyCopier(_assembly.operations());
-	solAssert(holds_alternative<yul::Block>(modified));
-	return yul::AsmPrinter()(std::get<yul::Block>(modified));
-}

libsolidity/codegen/experimental/IRGenerator.h

@@ -35,6 +35,7 @@ namespace solidity::frontend::experimental
 {
 
 class SourceUnit;
+class Analysis;
 
 class IRGenerator
 {
@@ -45,12 +46,14 @@ public:
 		RevertStrings /*_revertStrings*/,
 		std::map<std::string, unsigned> /*_sourceIndices*/,
 		langutil::DebugInfoSelection const& _debugInfoSelection,
-		langutil::CharStreamProvider const* _soliditySourceProvider
+		langutil::CharStreamProvider const* _soliditySourceProvider,
+		Analysis const& _analysis
 	):
 		m_evmVersion(_evmVersion),
 		m_eofVersion(_eofVersion),
 		m_debugInfoSelection(_debugInfoSelection),
-		m_soliditySourceProvider(_soliditySourceProvider)
+		m_soliditySourceProvider(_soliditySourceProvider),
+		m_analysis(_analysis)
 	{}
 
 	std::string run(
@@ -61,13 +64,13 @@ public:
 
 	std::string generate(ContractDefinition const& _contract) const;
 	std::string generate(FunctionDefinition const& _function) const;
-	std::string generate(InlineAssembly const& _assembly) const;
 private:
 	langutil::EVMVersion const m_evmVersion;
 	std::optional<uint8_t> const m_eofVersion;
 	OptimiserSettings const m_optimiserSettings;
 	langutil::DebugInfoSelection m_debugInfoSelection = {};
 	langutil::CharStreamProvider const* m_soliditySourceProvider = nullptr;
+	Analysis const& m_analysis;
 };
 
 }

libsolidity/codegen/experimental/IRGeneratorForStatements.cpp

@@ -18,9 +18,108 @@
 
 #include <libsolidity/codegen/experimental/IRGeneratorForStatements.h>
 
+#include <libyul/YulStack.h>
+#include <libyul/AsmPrinter.h>
+#include <libyul/AST.h>
+#include <libyul/optimiser/ASTCopier.h>
+
+#include <libsolidity/codegen/ir/Common.h>
+
 using namespace std;
 using namespace solidity;
 using namespace solidity::util;
 using namespace solidity::frontend;
 using namespace solidity::frontend::experimental;
 using namespace std::string_literals;
+
+std::string IRGeneratorForStatements::generate(ASTNode const& _node)
+{
+	_node.accept(*this);
+	return m_code.str();
+}
+
+
+namespace {
+
+struct CopyTranslate: public yul::ASTCopier
+{
+	CopyTranslate(
+		yul::Dialect const& _dialect,
+		map<yul::Identifier const*, InlineAssemblyAnnotation::ExternalIdentifierInfo> _references
+		): m_dialect(_dialect), m_references(std::move(_references)) {}
+
+	using ASTCopier::operator();
+
+	yul::Expression operator()(yul::Identifier const& _identifier) override
+	{
+		// The operator() function is only called in lvalue context. In rvalue context,
+		// only translate(yul::Identifier) is called.
+		if (m_references.count(&_identifier))
+			return translateReference(_identifier);
+		else
+			return ASTCopier::operator()(_identifier);
+	}
+
+	yul::YulString translateIdentifier(yul::YulString _name) override
+	{
+		if (m_dialect.builtin(_name))
+			return _name;
+		else
+			return yul::YulString{"usr$" + _name.str()};
+	}
+
+	yul::Identifier translate(yul::Identifier const& _identifier) override
+	{
+		if (!m_references.count(&_identifier))
+			return ASTCopier::translate(_identifier);
+
+		yul::Expression translated = translateReference(_identifier);
+		solAssert(holds_alternative<yul::Identifier>(translated));
+		return get<yul::Identifier>(std::move(translated));
+	}
+
+private:
+
+	/// Translates a reference to a local variable, potentially including
+	/// a suffix. Might return a literal, which causes this to be invalid in
+	/// lvalue-context.
+	yul::Expression translateReference(yul::Identifier const& _identifier)
+	{
+		auto const& reference = m_references.at(&_identifier);
+		auto const varDecl = dynamic_cast<VariableDeclaration const*>(reference.declaration);
+		solAssert(varDecl, "External reference in inline assembly to something that is not a variable declaration.");
+		// TODO: validate that variable is known and has word type.
+		string value = IRNames::localVariable(*varDecl);
+		return yul::Identifier{_identifier.debugData, yul::YulString{value}};
+	}
+
+	yul::Dialect const& m_dialect;
+	map<yul::Identifier const*, InlineAssemblyAnnotation::ExternalIdentifierInfo> m_references;
+};
+
+}
+
+bool IRGeneratorForStatements::visit(InlineAssembly const& _assembly)
+{
+	CopyTranslate bodyCopier{_assembly.dialect(), _assembly.annotation().externalReferences};
+	yul::Statement modified = bodyCopier(_assembly.operations());
+	solAssert(holds_alternative<yul::Block>(modified));
+	m_code << yul::AsmPrinter()(std::get<yul::Block>(modified));
+	return false;
+}
+
+bool IRGeneratorForStatements::visit(VariableDeclarationStatement const& _variableDeclarationStatement)
+{
+	solAssert(_variableDeclarationStatement.declarations().size() == 1, "multi variable declarations not supported");
+	solAssert(!_variableDeclarationStatement.initialValue(), "initial values not yet supported");
+	VariableDeclaration const* variableDeclaration = _variableDeclarationStatement.declarations().front().get();
+	solAssert(variableDeclaration);
+	// TODO: check the type of the variable; register local variable; initialize
+	m_code << "let " << IRNames::localVariable(*variableDeclaration) << "\n";
+	return false;
+}
+
+bool IRGeneratorForStatements::visitNode(ASTNode const&)
+{
+	solAssert(false, "Unsupported AST node during statement code generation.");
+}

libsolidity/codegen/experimental/IRGeneratorForStatements.h

@@ -21,18 +21,25 @@
 #include <libsolidity/ast/ASTVisitor.h>
 
 #include <functional>
+#include <sstream>
 
 namespace solidity::frontend::experimental
 {
+class Analysis;
 
 class IRGeneratorForStatements: public ASTConstVisitor
 {
 public:
-	IRGeneratorForStatements() {}
+	IRGeneratorForStatements(Analysis const& _analysis): m_analysis(_analysis) {}
 
+	std::string generate(ASTNode const& _node);
 private:
+	bool visit(InlineAssembly const& _inlineAssembly) override;
+	bool visit(VariableDeclarationStatement const& _variableDeclarationStatement) override;
 	/// Default visit will reject all AST nodes that are not explicitly supported.
 	bool visitNode(ASTNode const& _node) override;
+	Analysis const& m_analysis;
+	std::stringstream m_code;
 };
 
 }

libsolidity/interface/CompilerStack.cpp

@@ -670,9 +670,11 @@ bool CompilerStack::analyzeExperimental()
 	bool noErrors = true;
 	solAssert(m_maxAstId && *m_maxAstId >= 0);
 	m_experimentalAnalysis = make_unique<experimental::Analysis>(m_errorReporter, static_cast<uint64_t>(*m_maxAstId));
+	vector<shared_ptr<SourceUnit const>> sourceAsts;
 	for (Source const* source: m_sourceOrder)
 		if (source->ast)
-			if (!m_experimentalAnalysis->check(*source->ast))
+			sourceAsts.emplace_back(source->ast);
+	if (!m_experimentalAnalysis->check(sourceAsts))
 		noErrors = false;
 	return noErrors;
 }
@@ -1519,7 +1521,8 @@ void CompilerStack::generateIR(ContractDefinition const& _contract)
 			m_revertStrings,
 			sourceIndices(),
 			m_debugInfoSelection,
-			this
+			this,
+			*m_experimentalAnalysis
 		);
 		compiledContract.yulIR = generator.run(
 			_contract,

libsolidity/parsing/Parser.cpp

@@ -610,7 +610,9 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _isStateVari
 		else
 			break;
 	}
-	if (m_scanner->currentToken() == Token::Returns)
+	if (
+		m_scanner->currentToken() == (m_experimentalSolidityEnabledInCurrentSourceUnit ? Token::RightArrow : Token::Returns)
+	)
 	{
 		bool const permitEmptyParameterList = false;
 		advance();
@@ -1269,15 +1271,21 @@ ASTPointer<ParameterList> Parser::parseParameterList(
 	VarDeclParserOptions options(_options);
 	options.allowEmptyName = true;
 	expectToken(Token::LParen);
+	auto parseSingleVariableDeclaration = [&]() {
+		if (m_experimentalSolidityEnabledInCurrentSourceUnit)
+			return parsePostfixVariableDeclaration();
+		else
+			return parseVariableDeclaration(options);
+	};
 	if (!_allowEmpty || m_scanner->currentToken() != Token::RParen)
 	{
-		parameters.push_back(parseVariableDeclaration(options));
+		parameters.push_back(parseSingleVariableDeclaration());
 		while (m_scanner->currentToken() != Token::RParen)
 		{
 			if (m_scanner->currentToken() == Token::Comma && m_scanner->peekNextToken() == Token::RParen)
 				fatalParserError(7591_error, "Unexpected trailing comma in parameter list.");
 			expectToken(Token::Comma);
-			parameters.push_back(parseVariableDeclaration(options));
+			parameters.push_back(parseSingleVariableDeclaration());
 		}
 	}
 	nodeFactory.markEndPosition();
@@ -1658,12 +1666,66 @@ ASTPointer<RevertStatement> Parser::parseRevertStatement(ASTPointer<ASTString> c
 	return nodeFactory.createNode<RevertStatement>(_docString, errorCall);
 }
 
+ASTPointer<VariableDeclarationStatement> Parser::parsePostfixVariableDeclarationStatement(
+	ASTPointer<ASTString> const& _docString
+)
+{
+	RecursionGuard recursionGuard(*this);
+	ASTNodeFactory nodeFactory(*this);
+
+	expectToken(Token::Let);
+
+	vector<ASTPointer<VariableDeclaration>> variables;
+	variables.emplace_back(parsePostfixVariableDeclaration());
+	nodeFactory.setEndPositionFromNode(variables.back());
+
+	ASTPointer<Expression> value;
+	if (m_scanner->currentToken() == Token::Assign)
+	{
+		advance();
+		value = parseExpression();
+		nodeFactory.setEndPositionFromNode(value);
+	}
+	return nodeFactory.createNode<VariableDeclarationStatement>(_docString, variables, value);
+}
+
+ASTPointer<VariableDeclaration> Parser::parsePostfixVariableDeclaration()
+{
+	RecursionGuard recursionGuard(*this);
+	ASTNodeFactory nodeFactory(*this);
+
+	ASTPointer<StructuredDocumentation> const documentation = parseStructuredDocumentation();
+
+	nodeFactory.markEndPosition();
+	auto [identifier, nameLocation] = expectIdentifierWithLocation();
+
+	ASTPointer<TypeName> type;
+	if (m_scanner->currentToken() == Token::Colon)
+	{
+		advance();
+		type = parseTypeName();
+		nodeFactory.setEndPositionFromNode(type);
+	}
+
+	return nodeFactory.createNode<VariableDeclaration>(
+		type,
+		identifier,
+		nameLocation,
+		nullptr,
+		Visibility::Default,
+		documentation
+	);
+}
+
 ASTPointer<Statement> Parser::parseSimpleStatement(ASTPointer<ASTString> const& _docString)
 {
 	RecursionGuard recursionGuard(*this);
 	LookAheadInfo statementType;
 	IndexAccessedPath iap;
 
+	if (m_experimentalSolidityEnabledInCurrentSourceUnit && m_scanner->currentToken() == Token::Let)
+		return parsePostfixVariableDeclarationStatement(_docString);
+
 	if (m_scanner->currentToken() == Token::LParen)
 	{
 		ASTNodeFactory nodeFactory(*this);
@@ -1766,7 +1828,10 @@ pair<Parser::LookAheadInfo, Parser::IndexAccessedPath> Parser::tryParseIndexAcce
 	{
 	case LookAheadInfo::VariableDeclaration:
 	case LookAheadInfo::Expression:
-		return make_pair(statementType, IndexAccessedPath());
+		return make_pair(
+			m_experimentalSolidityEnabledInCurrentSourceUnit ? LookAheadInfo::Expression : statementType,
+			IndexAccessedPath()
+		);
 	default:
 		break;
 	}
@@ -1777,6 +1842,9 @@ pair<Parser::LookAheadInfo, Parser::IndexAccessedPath> Parser::tryParseIndexAcce
 	// VariableDeclarationStatement out of it.
 	IndexAccessedPath iap = parseIndexAccessedPath();
 
+	if (m_experimentalSolidityEnabledInCurrentSourceUnit)
+		return make_pair(LookAheadInfo::Expression, std::move(iap));
+
 	if (m_scanner->currentToken() == Token::Identifier || TokenTraits::isLocationSpecifier(m_scanner->currentToken()))
 		return make_pair(LookAheadInfo::VariableDeclaration, std::move(iap));
 	else

libsolidity/parsing/Parser.h

@@ -170,6 +170,14 @@ private:
 	std::pair<ASTPointer<ASTString>, langutil::SourceLocation> expectIdentifierWithLocation();
 	///@}
 
+	///@{
+	///@name Specialized parsing functions for the AST nodes of experimental solidity.
+	ASTPointer<VariableDeclarationStatement> parsePostfixVariableDeclarationStatement(
+		ASTPointer<ASTString> const& _docString
+	);
+	ASTPointer<VariableDeclaration> parsePostfixVariableDeclaration();
+	///@}
+
 	///@{
 	///@name Helper functions
 

libyul/AsmParser.cpp

@@ -116,8 +116,9 @@ unique_ptr<Block> Parser::parseInline(std::shared_ptr<Scanner> const& _scanner)
 {
 	m_recursionDepth = 0;
 
+	auto previousScannerKind = _scanner->scannerKind();
 	_scanner->setScannerMode(ScannerKind::Yul);
-	ScopeGuard resetScanner([&]{ _scanner->setScannerMode(ScannerKind::Solidity); });
+	ScopeGuard resetScanner([&]{ _scanner->setScannerMode(previousScannerKind); });
 
 	try
 	{

test/libsolidity/semanticTests/experimental/stub.sol

@@ -1,10 +1,21 @@
 pragma experimental solidity;
 
+function f(a:word) -> (b:word) {
+    assembly {
+        b := a
+    }
+}
+
 contract C {
 	fallback() external {
-	    word x;
+		let x : word;
+		let y : word;
 		assembly {
-			mstore(0, 42)
+			x := 0x42
+		}
+		y = x;
+		assembly {
+			mstore(0, y)
 			return(0, 32)
 		}
 	}
@@ -12,4 +23,4 @@ contract C {
 // ====
 // compileViaYul: true
 // ----
-// () -> 42
+// () -> 0x42