From 28625c6f45423e6edc5ca0e2932281769c0d431e Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Mon, 31 May 2021 10:05:50 -0700
Subject: [PATCH] Disable strict effects for legacy roots (again) (#21591)

---
 packages/react-reconciler/src/ReactFiber.new.js             | 6 +++++-
 packages/react-reconciler/src/ReactFiber.old.js             | 6 +++++-
 .../react-reconciler/src/ReactFiberClassComponent.new.js    | 4 ----
 .../react-reconciler/src/ReactFiberClassComponent.old.js    | 4 ----
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiber.new.js b/packages/react-reconciler/src/ReactFiber.new.js
index 2ea25195a7c0..a18514c50c0f 100644
--- a/packages/react-reconciler/src/ReactFiber.new.js
+++ b/packages/react-reconciler/src/ReactFiber.new.js
@@ -492,7 +492,11 @@ export function createFiberFromTypeAndProps(
         break;
       case REACT_STRICT_MODE_TYPE:
         fiberTag = Mode;
-        mode |= StrictLegacyMode | StrictEffectsMode;
+        mode |= StrictLegacyMode;
+        if (enableStrictEffects && (mode & ConcurrentMode) !== NoMode) {
+          // Strict effects should never run on legacy roots
+          mode |= StrictEffectsMode;
+        }
         break;
       case REACT_PROFILER_TYPE:
         return createFiberFromProfiler(pendingProps, mode, lanes, key);
diff --git a/packages/react-reconciler/src/ReactFiber.old.js b/packages/react-reconciler/src/ReactFiber.old.js
index 1e30bb9c7a3a..4fbbb5a00efc 100644
--- a/packages/react-reconciler/src/ReactFiber.old.js
+++ b/packages/react-reconciler/src/ReactFiber.old.js
@@ -492,7 +492,11 @@ export function createFiberFromTypeAndProps(
         break;
       case REACT_STRICT_MODE_TYPE:
         fiberTag = Mode;
-        mode |= StrictLegacyMode | StrictEffectsMode;
+        mode |= StrictLegacyMode;
+        if (enableStrictEffects && (mode & ConcurrentMode) !== NoMode) {
+          // Strict effects should never run on legacy roots
+          mode |= StrictEffectsMode;
+        }
         break;
       case REACT_PROFILER_TYPE:
         return createFiberFromProfiler(pendingProps, mode, lanes, key);
diff --git a/packages/react-reconciler/src/ReactFiberClassComponent.new.js b/packages/react-reconciler/src/ReactFiberClassComponent.new.js
index 44b9db7aacb2..c464b6c3bf41 100644
--- a/packages/react-reconciler/src/ReactFiberClassComponent.new.js
+++ b/packages/react-reconciler/src/ReactFiberClassComponent.new.js
@@ -923,7 +923,6 @@ function mountClassInstance(
       enableStrictEffects &&
       (workInProgress.mode & StrictEffectsMode) !== NoMode
     ) {
-      // Never double-invoke effects for legacy roots.
       fiberFlags |= MountLayoutDev;
     }
     workInProgress.flags |= fiberFlags;
@@ -1005,7 +1004,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;
@@ -1060,7 +1058,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;
@@ -1078,7 +1075,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;
diff --git a/packages/react-reconciler/src/ReactFiberClassComponent.old.js b/packages/react-reconciler/src/ReactFiberClassComponent.old.js
index ab2bb4379678..adb616c6262b 100644
--- a/packages/react-reconciler/src/ReactFiberClassComponent.old.js
+++ b/packages/react-reconciler/src/ReactFiberClassComponent.old.js
@@ -923,7 +923,6 @@ function mountClassInstance(
       enableStrictEffects &&
       (workInProgress.mode & StrictEffectsMode) !== NoMode
     ) {
-      // Never double-invoke effects for legacy roots.
       fiberFlags |= MountLayoutDev;
     }
     workInProgress.flags |= fiberFlags;
@@ -1005,7 +1004,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;
@@ -1060,7 +1058,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;
@@ -1078,7 +1075,6 @@ function resumeMountClassInstance(
         enableStrictEffects &&
         (workInProgress.mode & StrictEffectsMode) !== NoMode
       ) {
-        // Never double-invoke effects for legacy roots.
         fiberFlags |= MountLayoutDev;
       }
       workInProgress.flags |= fiberFlags;