Merge pull request #11741 from ethereum/shadowing_inlineasm_fix_yul_codegen

Fixed inline assembly external identifier access.

Author: chriseth

libsolidity/analysis/TypeChecker.cpp

@@ -742,8 +742,15 @@ bool TypeChecker::visit(InlineAssembly const& _inlineAssembly)
 		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;

libsolidity/codegen/CompilerContext.cpp

@@ -411,6 +411,7 @@ void CompilerContext::appendInlineAssembly(
 		yul::AbstractAssembly& _assembly
 	)
 	{
+		solAssert(_context == yul::IdentifierContext::RValue || _context == yul::IdentifierContext::LValue, "");
 		auto it = std::find(_localVariables.begin(), _localVariables.end(), _identifier.name.str());
 		solAssert(it != _localVariables.end(), "");
 		auto stackDepth = static_cast<size_t>(distance(it, _localVariables.end()));

libsolidity/codegen/ContractCompiler.cpp

@@ -708,6 +708,7 @@ bool ContractCompiler::visit(InlineAssembly const& _inlineAssembly)
 		yul::AbstractAssembly& _assembly
 	)
 	{
+		solAssert(_context == yul::IdentifierContext::RValue || _context == yul::IdentifierContext::LValue, "");
 		auto ref = _inlineAssembly.annotation().externalReferences.find(&_identifier);
 		solAssert(ref != _inlineAssembly.annotation().externalReferences.end(), "");
 		Declaration const* decl = ref->second.declaration;

libyul/AsmAnalysis.cpp

@@ -146,6 +146,13 @@ vector<YulString> AsmAnalyzer::operator()(Identifier const& _identifier)
 		}
 	}))
 	{
+		if (m_resolver)
+			// We found a local reference, make sure there is no external reference.
+			m_resolver(
+				_identifier,
+				yul::IdentifierContext::NonExternal,
+				m_currentScope->insideFunction()
+			);
 	}
 	else
 	{
@@ -308,7 +315,7 @@ vector<YulString> AsmAnalyzer::operator()(FunctionCall const& _funCall)
 
 		validateInstructions(_funCall);
 	}
-	else if (!m_currentScope->lookup(_funCall.functionName.name, GenericVisitor{
+	else if (m_currentScope->lookup(_funCall.functionName.name, GenericVisitor{
 		[&](Scope::Variable const&)
 		{
 			m_errorReporter.typeError(
@@ -323,6 +330,16 @@ vector<YulString> AsmAnalyzer::operator()(FunctionCall const& _funCall)
 			returnTypes = &_fun.returns;
 		}
 	}))
+	{
+		if (m_resolver)
+			// We found a local reference, make sure there is no external reference.
+			m_resolver(
+				_funCall.functionName,
+				yul::IdentifierContext::NonExternal,
+				m_currentScope->insideFunction()
+			);
+	}
+	else
 	{
 		if (!validateInstructions(_funCall))
 			m_errorReporter.declarationError(
@@ -539,6 +556,14 @@ void AsmAnalyzer::checkAssignment(Identifier const& _variable, YulString _valueT
 	bool found = false;
 	if (Scope::Identifier const* var = m_currentScope->lookup(_variable.name))
 	{
+		if (m_resolver)
+			// We found a local reference, make sure there is no external reference.
+			m_resolver(
+				_variable,
+				yul::IdentifierContext::NonExternal,
+				m_currentScope->insideFunction()
+			);
+
 		if (!holds_alternative<Scope::Variable>(*var))
 			m_errorReporter.typeError(2657_error, _variable.debugData->location, "Assignment requires variable.");
 		else if (!m_activeVariables.count(&std::get<Scope::Variable>(*var)))

libyul/backends/evm/AbstractAssembly.h

@@ -117,7 +117,7 @@ class AbstractAssembly
 	virtual void markAsInvalid() = 0;
 };
 
-enum class IdentifierContext { LValue, RValue, VariableDeclaration };
+enum class IdentifierContext { LValue, RValue, VariableDeclaration, NonExternal };
 
 /// Object that is used to resolve references and generate code for access to identifiers external
 /// to inline assembly (not used in standalone assembly mode).

test/libsolidity/semanticTests/inlineAssembly/external_identifier_access_shadowing.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public returns (uint x) {
+        assembly {
+            function g() -> f { f := 2 }
+            x := g()
+        }
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> 2

test/libsolidity/syntaxTests/inlineAssembly/external_identifier_access_shadowing.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public returns (uint x) {
+        assembly {
+            function g() -> x {
+                x := 42
+            }
+            x := g()
+        }
+    }
+}
+// ----
+// DeclarationError 6578: (123-124): Cannot access local Solidity variables from inside an inline assembly function.