Merge pull request #9329 from ethereum/optimiser-token

Disallow language keywords to be used as identifiers by NameDispenser and VarNameCleaner

Changelog.md

@@ -22,6 +22,7 @@ Bugfixes:
  * SMTChecker: Fix internal error on fixed bytes index access.
  * References Resolver: Fix internal bug when using constructor for library.
  * Yul Optimizer: Make function inlining order more resilient to whether or not unrelated source files are present.
+ * Yul Optimizer: Ensure that Yul keywords are not mistakenly used by the NameDispenser and VarNameCleaners. The bug would manifest as uncompilable code.
  * Type Checker: Disallow signed literals as exponent in exponentiation operator.
  * Allow `type(Contract).name` for abstract contracts and interfaces.
  * Type Checker: Disallow structs containing nested mapping in memory as parameters for library functions.

liblangutil/Token.cpp

@@ -152,6 +152,11 @@ static Token keywordByName(string const& _name)
 	return it == keywords.end() ? Token::Identifier : it->second;
 }
 
+bool isYulKeyword(string const& _literal)
+{
+	return _literal == "leave" || isYulKeyword(keywordByName(_literal));
+}
+
 tuple<Token, unsigned int, unsigned int> fromIdentifierOrKeyword(string const& _literal)
 {
 	auto positionM = find_if(_literal.begin(), _literal.end(), ::isdigit);

liblangutil/Token.h

@@ -327,6 +327,8 @@ namespace TokenTraits
 			tok == Token::TrueLiteral || tok == Token::FalseLiteral || tok == Token::HexStringLiteral || tok == Token::Hex;
 	}
 
+	bool isYulKeyword(std::string const& _literal);
+
 	inline Token AssignmentToBinaryOp(Token op)
 	{
 		solAssert(isAssignmentOp(op) && op != Token::Assign, "");

libyul/optimiser/NameDispenser.cpp

@@ -22,8 +22,10 @@
 #include <libyul/optimiser/NameDispenser.h>
 
 #include <libyul/optimiser/NameCollector.h>
+#include <libyul/optimiser/OptimizerUtilities.h>
 #include <libyul/AsmData.h>
 #include <libyul/Dialect.h>
+#include <libyul/YulString.h>
 
 #include <libsolutil/CommonData.h>
 
@@ -57,7 +59,5 @@ YulString NameDispenser::newName(YulString _nameHint)
 
 bool NameDispenser::illegalName(YulString _name)
 {
-	if (_name.empty() || m_usedNames.count(_name) || m_dialect.builtin(_name))
+	return isRestrictedIdentifier(m_dialect, _name) || m_usedNames.count(_name);
-		return true;
-	return false;
 }

libyul/optimiser/OptimizerUtilities.cpp

@@ -21,15 +21,19 @@
 
 #include <libyul/optimiser/OptimizerUtilities.h>
 
+#include <libyul/Dialect.h>
 #include <libyul/AsmData.h>
 
+#include <liblangutil/Token.h>
 #include <libsolutil/CommonData.h>
 
 #include <boost/range/algorithm_ext/erase.hpp>
 
 using namespace std;
 using namespace solidity;
+using namespace solidity::langutil;
 using namespace solidity::util;
+using namespace solidity::yul;
 
 void yul::removeEmptyBlocks(Block& _block)
 {
@@ -38,3 +42,8 @@ void yul::removeEmptyBlocks(Block& _block)
 	};
 	boost::range::remove_erase_if(_block.statements, isEmptyBlock);
 }
+
+bool yul::isRestrictedIdentifier(Dialect const& _dialect, YulString const& _identifier)
+{
+	return _identifier.empty() || TokenTraits::isYulKeyword(_identifier.str()) || _dialect.builtin(_identifier);
+}

libyul/optimiser/OptimizerUtilities.h

@@ -23,6 +23,8 @@
 
 #include <libsolutil/Common.h>
 #include <libyul/AsmDataForward.h>
+#include <libyul/Dialect.h>
+#include <libyul/YulString.h>
 
 namespace solidity::yul
 {
@@ -30,4 +32,8 @@ namespace solidity::yul
 /// Removes statements that are just empty blocks (non-recursive).
 void removeEmptyBlocks(Block& _block);
 
+/// Returns true if a given literal can not be used as an identifier.
+/// This includes Yul keywords and builtins of the given dialect.
+bool isRestrictedIdentifier(Dialect const& _dialect, YulString const& _identifier);
+
 }

libyul/optimiser/VarNameCleaner.cpp

@@ -17,6 +17,7 @@
 // SPDX-License-Identifier: GPL-3.0
 
 #include <libyul/optimiser/VarNameCleaner.h>
+#include <libyul/optimiser/OptimizerUtilities.h>
 #include <libyul/AsmData.h>
 #include <libyul/Dialect.h>
 
@@ -110,9 +111,7 @@ YulString VarNameCleaner::findCleanName(YulString const& _name) const
 
 bool VarNameCleaner::isUsedName(YulString const& _name) const
 {
-	if (_name.empty() || m_dialect.builtin(_name) || m_usedNames.count(_name))
+	return isRestrictedIdentifier(m_dialect, _name) || m_usedNames.count(_name);
-		return true;
-	return false;
 }
 
 YulString VarNameCleaner::stripSuffix(YulString const& _name) const