From 21f2dd52ae4131b6e8d694d875e657f7e2b1c443 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 22 Jun 2020 10:43:18 -0400
Subject: [PATCH] Merge debug reducer to avoid Combine leak (#195)

---
 .../Debugging/ReducerDebugging.swift                 |  2 +-
 Sources/ComposableArchitecture/Effect.swift          | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift b/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift
index 6def4397088c..193af1d8c3cd 100644
--- a/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift
+++ b/Sources/ComposableArchitecture/Debugging/ReducerDebugging.swift
@@ -106,7 +106,7 @@ extension Reducer {
         guard let localAction = toLocalAction.extract(from: action) else { return effects }
         let nextState = toLocalState(state)
         let debugEnvironment = toDebugEnvironment(environment)
-        return .concatenate(
+        return .merge(
           .fireAndForget {
             debugEnvironment.queue.async {
               let actionOutput =
diff --git a/Sources/ComposableArchitecture/Effect.swift b/Sources/ComposableArchitecture/Effect.swift
index fb169aaa61e9..f1be9ac32834 100644
--- a/Sources/ComposableArchitecture/Effect.swift
+++ b/Sources/ComposableArchitecture/Effect.swift
@@ -170,6 +170,12 @@ public struct Effect<Output, Failure: Error>: Publisher {
   /// Concatenates a variadic list of effects together into a single effect, which runs the effects
   /// one after the other.
   ///
+  /// - Warning: Combine's `Publishers.Concatenate` operator, which this function uses, can leak
+  ///   when its suffix is a `Publishers.MergeMany` operator, which is used throughout the
+  ///   Composable Architecture in functions like `Reducer.combine`.
+  ///
+  ///   Feedback filed: <https://gist.github.com/mbrandonw/611c8352e1bd1c22461bd505e320ab58>
+  ///
   /// - Parameter effects: A variadic list of effects.
   /// - Returns: A new effect
   public static func concatenate(_ effects: Effect...) -> Effect {
@@ -179,6 +185,12 @@ public struct Effect<Output, Failure: Error>: Publisher {
   /// Concatenates a collection of effects together into a single effect, which runs the effects one
   /// after the other.
   ///
+  /// - Warning: Combine's `Publishers.Concatenate` operator, which this function uses, can leak
+  ///   when its suffix is a `Publishers.MergeMany` operator, which is used throughout the
+  ///   Composable Architecture in functions like `Reducer.combine`.
+  ///
+  ///   Feedback filed: <https://gist.github.com/mbrandonw/611c8352e1bd1c22461bd505e320ab58>
+  ///
   /// - Parameter effects: A collection of effects.
   /// - Returns: A new effect
   public static func concatenate<C: Collection>(