From e16c0c4133d4dcd624c6c1962db69449cb3da568 Mon Sep 17 00:00:00 2001
From: Jason Cobb <jason.e.cobb@gmail.com>
Date: Wed, 25 Mar 2020 23:46:26 -0400
Subject: [PATCH] Convert operator+(Population, Population) into a hidden
 friend

---
 tools/yulPhaser/Population.cpp | 6 ++++++
 tools/yulPhaser/Population.h   | 7 ++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/tools/yulPhaser/Population.cpp b/tools/yulPhaser/Population.cpp
index 87df4e59b..71b32da70 100644
--- a/tools/yulPhaser/Population.cpp
+++ b/tools/yulPhaser/Population.cpp
@@ -118,15 +118,21 @@ Population Population::crossover(PairSelection const& _selection, function<Cross
 	return Population(m_fitnessMetric, crossedIndividuals);
 }
 
+namespace solidity::phaser
+{
+
 Population operator+(Population _a, Population _b)
 {
 	// This operator is meant to be used only with populations sharing the same metric (and, to make
 	// things simple, "the same" here means the same exact object in memory).
 	assert(_a.m_fitnessMetric == _b.m_fitnessMetric);
 
+	using ::operator+; // Import the std::vector concat operator from CommonData.h
 	return Population(_a.m_fitnessMetric, move(_a.m_individuals) + move(_b.m_individuals));
 }
 
+}
+
 bool Population::operator==(Population const& _other) const
 {
 	// We consider populations identical only if they share the same exact instance of the metric.
diff --git a/tools/yulPhaser/Population.h b/tools/yulPhaser/Population.h
index f8f12632e..151474171 100644
--- a/tools/yulPhaser/Population.h
+++ b/tools/yulPhaser/Population.h
@@ -33,10 +33,6 @@ 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
 {
 
@@ -108,7 +104,8 @@ public:
 	Population select(Selection const& _selection) const;
 	Population mutate(Selection const& _selection, std::function<Mutation> _mutation) const;
 	Population crossover(PairSelection const& _selection, std::function<Crossover> _crossover) const;
-	friend Population (::operator+)(Population _a, Population _b);
+
+	friend Population operator+(Population _a, Population _b);
 
 	std::shared_ptr<FitnessMetric> fitnessMetric() { return m_fitnessMetric; }
 	std::vector<Individual> const& individuals() const { return m_individuals; }