fixup! fixup! fixup! Review comments

Author: nikola-matic

Changelog.md

@@ -9,7 +9,7 @@ Compiler Features:
 Bugfixes:
  * SMTChecker: Fix internal error on mapping access caused by too strong requirements on sort compatibility of the index and mapping domain.
  * SMTChecker: Fix internal error when using bitwise operators with an array element as argument.
- * Yul Optimizer: Fix ``SSATransform`` step that would sometimes cause non-deterministic output in cases where one or more unused contracts were added to the compilation pipeline.
+ * Yul Optimizer: Fix the order of assignments generated by ``SSATransform`` being dependent on AST IDs, sometimes resulting in different (but equivalent) bytecode when unrelated files were added to the compilation pipeline.
 
 
 ### 0.8.25 (2023-03-14)

libsolutil/CommonData.h

@@ -159,6 +159,14 @@ inline std::multiset<T...>& operator-=(std::multiset<T...>& _a, C const& _b)
 	return _a;
 }
 
+/// Remove the elements of a container from a vector
+template <class T, class U> std::vector<T>& operator-=(std::vector<T>& _a, U& _b)
+{
+	for (auto const& i: _b)
+		_a.erase(std::find(_a.begin(), _a.end(), i));
+	return _a;
+}
+
 namespace solidity::util
 {
 
@@ -468,14 +476,6 @@ void appendMissing(std::vector<T>& _destination, std::vector<T> const& _source)
 		tryEmplaceBack(_destination, elem);
 }
 
-/// Function that removes all elements present in vector @param _sub from vector @param _super.
-template <class T>
-void removeVectorSubset(std::vector<T>& _super, std::vector<T> const& _sub)
-{
-	for (auto const& elem: _sub)
-		_super.erase(std::find(_super.begin(), _super.end(), elem));
-}
-
 /// Function that iterates over a vector, calling a function on each of its
 /// elements. If that function returns a vector, the element is replaced by
 /// the returned vector. During the iteration, the original vector is only valid

libyul/optimiser/SSATransform.cpp

@@ -272,7 +272,7 @@ void IntroduceControlFlowSSA::operator()(Block& _block)
 
 	util::appendMissing(m_variablesToReassign, assignedVariables);
 	m_variablesInScope -= variablesDeclaredHere;
-	util::removeVectorSubset(m_variablesToReassign, variablesDeclaredHere);
+	m_variablesToReassign -= variablesDeclaredHere;
 }
 
 /**