Remove the warning for setState on unmounted components

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Roact Changelog
 
 ## Unreleased Changes
+* Removed the warning for `setState` on unmounted components to eliminate false positive warnings, matching upstream React ([#323](https://github.com/Roblox/roact/pull/323)).
 
 ## [1.4.2](https://github.com/Roblox/roact/releases/tag/v1.4.2) (October 6th, 2021)
 * Fixed forwardRef doc code referencing React instead of Roact ([#310](https://github.com/Roblox/roact/pull/310)).

src/Component.lua

@@ -100,21 +100,22 @@ function Component:setState(mapState)
 	local lifecyclePhase = internalData.lifecyclePhase
 
 	--[[
-		When preparing to update, rendering, or unmounting, it is not safe
+		When preparing to update, render, or unmount, it is not safe
 		to call `setState` as it will interfere with in-flight updates. It's
 		also disallowed during unmounting
 	]]
 	if
 		lifecyclePhase == ComponentLifecyclePhase.ShouldUpdate
 		or lifecyclePhase == ComponentLifecyclePhase.WillUpdate
 		or lifecyclePhase == ComponentLifecyclePhase.Render
-		or lifecyclePhase == ComponentLifecyclePhase.WillUnmount
 	then
 		local messageTemplate = invalidSetStateMessages[internalData.lifecyclePhase]
 
 		local message = messageTemplate:format(tostring(internalData.componentClass))
-
 		error(message, 2)
+	elseif lifecyclePhase == ComponentLifecyclePhase.WillUnmount then
+		-- Should not print error message. See https://github.com/facebook/react/pull/22114
+		return
 	end
 
 	local pendingState = internalData.pendingState

src/Component.spec/setState.spec.lua

@@ -109,7 +109,7 @@ return function()
 			expect(result:match("TestComponent")).to.be.ok()
 		end)
 
-		it("should throw when called in willUnmount", function()
+		it("should not throw when called in willUnmount", function()
 			local TestComponent = Component:extend("TestComponent")
 
 			function TestComponent:render()
@@ -125,11 +125,9 @@ return function()
 			local element = createElement(TestComponent)
 			local tree = noopReconciler.mountVirtualTree(element)
 
-			local success, result = pcall(noopReconciler.unmountVirtualTree, tree)
+			local success, _ = pcall(noopReconciler.unmountVirtualTree, tree)
 
-			expect(success).to.equal(false)
-			expect(result:match("willUnmount")).to.be.ok()
-			expect(result:match("TestComponent")).to.be.ok()
+			expect(success).to.equal(true)
 		end)
 
 		it("should remove values from state when the value is None", function()

src/invalidSetStateMessages.lua

@@ -15,12 +15,6 @@ Consider using the didUpdate method instead, or using getDerivedStateFromProps.
 
 Check the definition of willUpdate in the component %q.]]
 
-invalidSetStateMessages[ComponentLifecyclePhase.WillUnmount] = [[
-setState cannot be used in the willUnmount lifecycle method.
-A component that is being unmounted cannot be updated!
-
-Check the definition of willUnmount in the component %q.]]
-
 invalidSetStateMessages[ComponentLifecyclePhase.ShouldUpdate] = [[
 setState cannot be used in the shouldUpdate lifecycle method.
 shouldUpdate must be a pure function that only depends on props and state.