Adding fixes for signedness conversion warnings in libyul

Co-authored-by: Kamil Śliwak <kamil.sliwak@codepoets.it>

libyul/optimiser/DeadCodeEliminator.cpp

@@ -51,10 +51,10 @@ void DeadCodeEliminator::operator()(Block& _block)
 	tie(controlFlowChange, index) = TerminationFinder{m_dialect}.firstUnconditionalControlFlowChange(_block.statements);
 
 	// Erase everything after the terminating statement that is not a function definition.
-	if (controlFlowChange != TerminationFinder::ControlFlow::FlowOut && index != size_t(-1))
+	if (controlFlowChange != TerminationFinder::ControlFlow::FlowOut && index != std::numeric_limits<size_t>::max())
 		_block.statements.erase(
 			remove_if(
-				_block.statements.begin() + index + 1,
+				_block.statements.begin() + static_cast<ptrdiff_t>(index) + 1,
 				_block.statements.end(),
 				[] (Statement const& _s) { return !holds_alternative<yul::FunctionDefinition>(_s); }
 			),
@@ -63,4 +63,3 @@ void DeadCodeEliminator::operator()(Block& _block)
 
 	ASTModifier::operator()(_block);
 }
-

libyul/optimiser/ExpressionJoiner.cpp

@@ -119,7 +119,7 @@ void ExpressionJoiner::decrementLatestStatementPointer()
 void ExpressionJoiner::resetLatestStatementPointer()
 {
 	m_currentBlock = nullptr;
-	m_latestStatementInBlock = size_t(-1);
+	m_latestStatementInBlock = numeric_limits<size_t>::max();
 }
 
 Statement* ExpressionJoiner::latestStatement()

libyul/optimiser/Semantics.cpp

@@ -180,7 +180,7 @@ pair<TerminationFinder::ControlFlow, size_t> TerminationFinder::firstUncondition
 		if (controlFlow != ControlFlow::FlowOut)
 			return {controlFlow, i};
 	}
-	return {ControlFlow::FlowOut, size_t(-1)};
+	return {ControlFlow::FlowOut, numeric_limits<size_t>::max()};
 }
 
 TerminationFinder::ControlFlow TerminationFinder::controlFlowKind(Statement const& _statement)

libyul/optimiser/StackCompressor.cpp

@@ -178,14 +178,14 @@ bool StackCompressor::run(
 			eliminateVariables(
 				_dialect,
 				std::get<Block>(_object.code->statements.at(0)),
-				stackSurplus.at({}),
+				static_cast<size_t>(stackSurplus.at({})),
 				allowMSizeOptimzation
 			);
 		}
 
 		for (size_t i = 1; i < _object.code->statements.size(); ++i)
 		{
-			FunctionDefinition& fun = std::get<FunctionDefinition>(_object.code->statements[i]);
+			auto& fun = std::get<FunctionDefinition>(_object.code->statements[i]);
 			if (!stackSurplus.count(fun.name))
 				continue;
 
@@ -193,7 +193,7 @@ bool StackCompressor::run(
 			eliminateVariables(
 				_dialect,
 				fun,
-				stackSurplus.at(fun.name),
+				static_cast<size_t>(stackSurplus.at(fun.name)),
 				allowMSizeOptimzation
 			);
 		}