[yul-phaser] Population: Add operator+()

tools/yulPhaser/Population.cpp

@@ -19,6 +19,7 @@
 
 #include <tools/yulPhaser/Program.h>
 
+#include <libsolutil/CommonData.h>
 #include <libsolutil/CommonIO.h>
 
 #include <algorithm>
@@ -117,6 +118,13 @@ void Population::run(optional<size_t> _numRounds, ostream& _outputStream)
 	}
 }
 
+Population operator+(Population _a, Population _b)
+{
+	assert(toString(_a.m_program) == toString(_b.m_program));
+
+	return Population(_a.m_program, move(_a.m_individuals) + move(_b.m_individuals));
+}
+
 ostream& phaser::operator<<(ostream& _stream, Population const& _population)
 {
 	auto individual = _population.m_individuals.begin();

tools/yulPhaser/Population.h

@@ -28,6 +28,17 @@
 namespace solidity::phaser
 {
 
+class Population;
+
+}
+
+// This operator+ must be declared in the global namespace. Otherwise it would shadow global
+// operator+ overloads from CommonData.h (e.g. the one for vector) in the namespace it was declared in.
+solidity::phaser::Population operator+(solidity::phaser::Population _a, solidity::phaser::Population _b);
+
+namespace solidity::phaser
+{
+
 /**
  * Information describing the state of an individual member of the population during the course
  * of the genetic algorithm.
@@ -74,6 +85,7 @@ public:
 	);
 
 	void run(std::optional<size_t> _numRounds, std::ostream& _outputStream);
+	friend Population (::operator+)(Population _a, Population _b);
 
 	std::vector<Individual> const& individuals() const { return m_individuals; }