From d785d58eb77677e71615e35eb85832b3b0a19b3c Mon Sep 17 00:00:00 2001
From: Philipp Spiess <hello@philippspiess.com>
Date: Wed, 18 Oct 2017 10:45:22 +0200
Subject: [PATCH 1/2] Fix Map#concat

#1373 made `Map#concat` an alias for `Map#merge` but defined the alias
before `Map#merge` was defined, resulting in `Map#concat` being
undefined.

This fixes the issue and adds a regression test.
---
 __tests__/Map.ts | 8 ++++++++
 src/Map.js       | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/__tests__/Map.ts b/__tests__/Map.ts
index 509517e108..66af8a01cd 100644
--- a/__tests__/Map.ts
+++ b/__tests__/Map.ts
@@ -129,6 +129,14 @@ describe('Map', () => {
     expect(m3.toObject()).toEqual({a: 'A', b: 'BB', c: 'C', wow: 'OO', d: 'DD'});
   });
 
+  it('concatenates two maps (alias for merge)', () => {
+    const m1 = Map({ a: 'A', b: 'B', c: 'C' });
+    const m2 = Map({ wow: 'OO', d: 'DD', b: 'BB' });
+    expect(m2.toObject()).toEqual({ wow: 'OO', d: 'DD', b: 'BB' });
+    const m3 = m1.concat(m2);
+    expect(m3.toObject()).toEqual({a: 'A', b: 'BB', c: 'C', wow: 'OO', d: 'DD'});
+  });
+
   it('accepts null as a key', () => {
     const m1 = Map<any, any>();
     const m2 = m1.set(null, 'null');
diff --git a/src/Map.js b/src/Map.js
index 750ea81a8b..e73626786f 100644
--- a/src/Map.js
+++ b/src/Map.js
@@ -170,7 +170,7 @@ export const MapPrototype = Map.prototype;
 MapPrototype[IS_MAP_SENTINEL] = true;
 MapPrototype[DELETE] = MapPrototype.remove;
 MapPrototype.removeAll = MapPrototype.deleteAll;
-MapPrototype.concat = MapPrototype.merge;
+MapPrototype.concat = merge;
 MapPrototype.setIn = setIn;
 MapPrototype.removeIn = MapPrototype.deleteIn = deleteIn;
 MapPrototype.update = update;

From 1d2907b8f84789575b473e888bc1147bf2bdb975 Mon Sep 17 00:00:00 2001
From: Lee Byron <lee@leebyron.com>
Date: Wed, 18 Oct 2017 12:39:06 -0700
Subject: [PATCH 2/2] Alias on same line

---
 src/Map.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Map.js b/src/Map.js
index e73626786f..035a0d42e4 100644
--- a/src/Map.js
+++ b/src/Map.js
@@ -170,12 +170,11 @@ export const MapPrototype = Map.prototype;
 MapPrototype[IS_MAP_SENTINEL] = true;
 MapPrototype[DELETE] = MapPrototype.remove;
 MapPrototype.removeAll = MapPrototype.deleteAll;
-MapPrototype.concat = merge;
 MapPrototype.setIn = setIn;
 MapPrototype.removeIn = MapPrototype.deleteIn = deleteIn;
 MapPrototype.update = update;
 MapPrototype.updateIn = updateIn;
-MapPrototype.merge = merge;
+MapPrototype.merge = MapPrototype.concat = merge;
 MapPrototype.mergeWith = mergeWith;
 MapPrototype.mergeDeep = mergeDeep;
 MapPrototype.mergeDeepWith = mergeDeepWith;