Warn about undefined return value for memo and forwardRef #19550

bvaughn · 2020-08-06T18:27:55Z

Seems wrong that we weren't warning about this before.

Resolves #19548

codesandbox-ci · 2020-08-06T18:30:19Z

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acdlite · 2020-08-06T18:31:10Z

packages/react-reconciler/src/ReactChildFiber.old.js

+        case FunctionComponent:
+        case MemoComponent:
+        case SimpleMemoComponent:
+        case ForwardRef: {


I don't think you need MemoComponent, since that one always wraps around another fiber. SimpleMemoComponent should be sufficient.

Oh right. I was wondering if I was forgetting one.

Too many component types 😆

Hm. I can just add the case, but I'm not sure how to write a test that hits this code path for Block.

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…9550)" This reverts commit a63893f.

Summary: This sync includes the following changes: - **[eaaf4cbce](facebook/react@eaaf4cbce )**: 17.0.1 //<Dan Abramov>// - **[6f62abb58](facebook/react@6f62abb58 )**: Remove usage of Array#fill ([#20071](facebook/react#20071)) //<Dan Abramov>// - **[40cfe1f48](facebook/react@40cfe1f48 )**: Update CHANGELOG.md //<Dan Abramov>// - **[f021a983a](facebook/react@f021a983a )**: Bump versions for 17 ([#20062](facebook/react#20062)) //<Dan Abramov>// - **[d1bb4d851](facebook/react@d1bb4d851 )**: Profiler: Include ref callbacks in onCommit duration ([#20060](facebook/react#20060)) //<Brian Vaughn>// - **[c59c3dfe5](facebook/react@c59c3dfe5 )**: useRef: Warn about reading or writing mutable values during render ([#18545](facebook/react#18545)) //<Brian Vaughn>// - **[7b6cac952](facebook/react@7b6cac952 )**: Improved Profiler commit hooks test ([#20053](facebook/react#20053)) //<Brian Vaughn>// - **[dfb6a4033](facebook/react@dfb6a4033 )**: [Fast Refresh] Fix crashes caused by rogue Proxies ([#20030](facebook/react#20030)) ([#20039](facebook/react#20039)) //<Kai Riemann>// - **[37cb732c5](facebook/react@37cb732c5 )**: Use bitwise OR to define flag masks ([#20044](facebook/react#20044)) //<Andrew Clark>// - **[eb3181e77](facebook/react@eb3181e77 )**: Add Visibility flag for hiding/unhiding trees ([#20043](facebook/react#20043)) //<Andrew Clark>// - **[0dd809bdf](facebook/react@0dd809bdf )**: Remove last schedulePassiveEffectCallback call ([#20042](facebook/react#20042)) //<Andrew Clark>// - **[8df7b7911](facebook/react@8df7b7911 )**: Remove Passive flag from "before mutation" phase ([#20038](facebook/react#20038)) //<Andrew Clark>// - **[c57fe4a2c](facebook/react@c57fe4a2c )**: ReactIs.isValidElementType Unit Test extended with PureComponent case ([#20033](facebook/react#20033)) //<adasq>// - **[02da938fd](facebook/react@02da938fd )**: Don't double-invoke effects in legacy roots ([#20028](facebook/react#20028)) //<Brian Vaughn>// - **[d95c4938d](facebook/react@d95c4938d )**: [EventSystem] Revise onBeforeBlur propagation mechanics ([#20020](facebook/react#20020)) //<Dominic Gannaway>// - **[f46a80ae1](facebook/react@f46a80ae1 )**: Update outdated links and fix two broken links ([#19985](facebook/react#19985)) //<Saikat Guha>// - **[0a4c7c565](facebook/react@0a4c7c565 )**: [Flight] Don't warn for key, but error for ref ([#19986](facebook/react#19986)) //<Sebastian Markbåge>// - **[993ca533b](facebook/react@993ca533b )**: Enable eager listeners statically ([#19983](facebook/react#19983)) //<Dan Abramov>// - **[40c52de96](facebook/react@40c52de96 )**: [Flight] Add Runtime Errors for Non-serializable Values ([#19980](facebook/react#19980)) //<Sebastian Markbåge>// - **[1992d9730](facebook/react@1992d9730 )**: Revert "Temporarily disable Profiler commit hooks flag ([#19900](facebook/react#19900))" ([#19960](facebook/react#19960)) //<Brian Vaughn>// - **[44d39c4d7](facebook/react@44d39c4d7 )**: Removed skip-error-boundaries modifications from old fork ([#19961](facebook/react#19961)) //<Brian Vaughn>// - **[cc77be957](facebook/react@cc77be957 )**: Remove unnecessary error overriding in ([#19949](facebook/react#19949)) //<Paul Doyle>// - **[97625272a](facebook/react@97625272a )**: Debug tracing tests for CPU bound suspense ([#19943](facebook/react#19943)) //<Brian Vaughn>// - **[43363e279](facebook/react@43363e279 )**: Fix codestyle for typeof comparison ([#19928](facebook/react#19928)) //<Eugene Maslovich>// - **[5427b4657](facebook/react@5427b4657 )**: Temporarily disable Profiler commit hooks flag ([#19900](facebook/react#19900)) //<Brian Vaughn>// - **[1faf9e3dd](facebook/react@1faf9e3dd )**: Suspense for CPU-bound trees ([#19936](facebook/react#19936)) //<Andrew Clark>// - **[7f08e908b](facebook/react@7f08e908b )**: Fix missing context to componentDidMount() when double-invoking lifecycles ([#19935](facebook/react#19935)) //<Brian Vaughn>// - **[9198a5cec](facebook/react@9198a5cec )**: Refactor layout effect methods ([#19895](facebook/react#19895)) //<Brian Vaughn>// - **[ba82eea38](facebook/react@ba82eea38 )**: Remove disableSchedulerTimeoutInWorkLoop flag ([#19902](facebook/react#19902)) //<Andrew Clark>// - **[c63741fb3](facebook/react@c63741fb3 )**: offscreen double invoke effects ([#19523](facebook/react#19523)) //<Luna Ruan>// - **[c6917346f](facebook/react@c6917346f )**: Fixed broken Profiler test ([#19894](facebook/react#19894)) //<Brian Vaughn>// - **[87c023b1c](facebook/react@87c023b1c )**: Profiler onRender only called when we do work ([#19885](facebook/react#19885)) //<Brian Vaughn>// - **[81aaee56a](facebook/react@81aaee56a )**: Don't call onCommit et al if there are no effects ([#19863](facebook/react#19863)) //<Andrew Clark>// - **[7355bf575](facebook/react@7355bf575 )**: Consolidate commit phase hook functions ([#19864](facebook/react#19864)) //<Andrew Clark>// - **[bc6b7b6b1](facebook/react@bc6b7b6b1 )**: Don't trigger lazy in DEV during element creation ([#19871](facebook/react#19871)) //<Dan Abramov>// - **[a774502e0](facebook/react@a774502e0 )**: Use single quotes in getComponentName return ([#19873](facebook/react#19873)) //<Gustavo Saiani>// - **[8b2d3783e](facebook/react@8b2d3783e )**: Use Passive flag to schedule onPostCommit ([#19862](facebook/react#19862)) //<Andrew Clark>// - **[50d9451f3](facebook/react@50d9451f3 )**: Improve DevTools editing interface ([#19774](facebook/react#19774)) //<Brian Vaughn>// - **[6fddca27e](facebook/react@6fddca27e )**: Remove passive intervention flag ([#19849](facebook/react#19849)) //<Dan Abramov>// - **[36df9185c](facebook/react@36df9185c )**: chore(docs): Removed outdated comment about fb.me link ([#19830](facebook/react#19830)) //<Adnaan Bheda>// - **[16fb2b6f9](facebook/react@16fb2b6f9 )**: Moved resetChildLanes into complete work ([#19836](facebook/react#19836)) //<Brian Vaughn>// - **[cc581065d](facebook/react@cc581065d )**: eslint-plugin-react-hooks@4.1.2 //<Dan Abramov>// - **[0044805c8](facebook/react@0044805c8 )**: Update CHANGELOG.md //<Dan Abramov>// - **[0f70d4dd6](facebook/react@0f70d4dd6 )**: Consider components in jsx as missing dependencies in typescript-eslint/parser@4.x ([#19815](facebook/react#19815)) //<Sebastian Silbermann>// - **[84558c61b](facebook/react@84558c61b )**: Don't visit passive effects during layout phase ([#19809](facebook/react#19809)) //<Andrew Clark>// - **[ad8a0a8cd](facebook/react@ad8a0a8cd )**: eslint-plugin-react-hooks@4.1.1 //<Dan Abramov>// - **[77544a0d6](facebook/react@77544a0d6 )**: Update CHANGELOG.md //<Dan Abramov>// - **[ed4fdfc73](facebook/react@ed4fdfc73 )**: test(eslint-plugin-react-hooks): Run with TS parsers >= 2.x ([#19792](facebook/react#19792)) //<Sebastian Silbermann>// - **[cd75f93c0](facebook/react@cd75f93c0 )**: eslint-plugin-react-hooks: fix compatibility with typescript-eslint/parser@4.0.0+ ([#19751](facebook/react#19751)) //<Matthias Schiffer>// - **[781212aab](facebook/react@781212aab )**: Remove double space in test name ([#19762](facebook/react#19762)) //<Gustavo Saiani>// - **[e7b255341](facebook/react@e7b255341 )**: Internal `act`: Flush timers at end of scope ([#19788](facebook/react#19788)) //<Andrew Clark>// - **[d17086c7c](facebook/react@d17086c7c )**: Decouple public, internal act implementation ([#19745](facebook/react#19745)) //<Andrew Clark>// - **[d38ec17b1](facebook/react@d38ec17b1 )**: [Flight] Set dispatcher for duration of performWork() ([#19776](facebook/react#19776)) //<Joseph Savona>// - **[4f3f7eeb7](facebook/react@4f3f7eeb7 )**: Bugfix: Effect clean up when deleting suspended tree ([#19752](facebook/react#19752)) //<Andrew Clark>// - **[7baf9d412](facebook/react@7baf9d412 )**: Combine Flags and SubtreeFlags types ([#19775](facebook/react#19775)) //<Andrew Clark>// - **[166544360](facebook/react@166544360 )**: Rename effect fields ([#19755](facebook/react#19755)) //<Andrew Clark>// - **[708fa77a7](facebook/react@708fa77a7 )**: Decrease expiration time of input updates ([#19772](facebook/react#19772)) //<Andrew Clark>// - **[36df483af](facebook/react@36df483af )**: Add feature flag to disable scheduler timeout in work loop ([#19771](facebook/react#19771)) //<Ricky>// - **[bcc0aa463](facebook/react@bcc0aa463 )**: Revert "Revert "Remove onScroll bubbling flag ([#19535](facebook/react#19535))" ([#19655](facebook/react#19655))" ([#19761](facebook/react#19761)) //<Dan Abramov>// - **[99cae887f](facebook/react@99cae887f )**: Add failing test for passive effect cleanup functions and memoized components ([#19750](facebook/react#19750)) //<Brian Vaughn>// - **[2cfd73c4d](facebook/react@2cfd73c4d )**: Fix typo in comment (Noticable→Noticeable) ([#19737](facebook/react#19737)) //<Ikko Ashimine>// - **[53e622ca7](facebook/react@53e622ca7 )**: Fix instances of function declaration after return ([#19733](facebook/react#19733)) //<Bhumij Gupta>// - **[b7d18c4da](facebook/react@b7d18c4da )**: Support Babel's envName option in React Refresh plugin ([#19009](facebook/react#19009)) //<Kevin Weber>// - **[1f38dcff6](facebook/react@1f38dcff6 )**: Remove withSuspenseConfig ([#19724](facebook/react#19724)) //<Andrew Clark>// - **[1396e4a8f](facebook/react@1396e4a8f )**: Fixes eslint warning when node type is ChainExpression ([#19680](facebook/react#19680)) //<Pascal Fong Kye>// - **[a8500be89](facebook/react@a8500be89 )**: Add `startTransition` as a known stable method ([#19720](facebook/react#19720)) //<Andrew Clark>// - **[380dc95de](facebook/react@380dc95de )**: Revert "Append text string to <Text> error message ([#19581](facebook/react#19581))" ([#19723](facebook/react#19723)) //<Timothy Yung>// - **[ddd1faa19](facebook/react@ddd1faa19 )**: Remove config argument from useTransition ([#19719](facebook/react#19719)) //<Andrew Clark>// - **[92fcd46cc](facebook/react@92fcd46cc )**: Replace SuspenseConfig object with an integer ([#19706](facebook/react#19706)) //<Andrew Clark>// - **[b754caaaf](facebook/react@b754caaaf )**: Enable eager listeners in open source ([#19716](facebook/react#19716)) //<Dan Abramov>// - **[c1ac05215](facebook/react@c1ac05215 )**: [Flight] Support more element types and Hooks for Server and Hybrid Components ([#19711](facebook/react#19711)) //<Dan Abramov>// - **[1eaafc9ad](facebook/react@1eaafc9ad )**: Clean up timeoutMs-related implementation details ([#19704](facebook/react#19704)) //<Andrew Clark>// - **[8da0da093](facebook/react@8da0da093 )**: Disable timeoutMs argument ([#19703](facebook/react#19703)) //<Andrew Clark>// - **[60ba723bf](facebook/react@60ba723bf )**: Add SuspenseList to devTools ([#19684](facebook/react#19684)) //<Ben Pernick>// - **[5564f2c95](facebook/react@5564f2c95 )**: Add React.startTransition ([#19696](facebook/react#19696)) //<Ricky>// - **[c4e0768d7](facebook/react@c4e0768d7 )**: Remove unused argument from `finishConcurrentRender` ([#19689](facebook/react#19689)) //<inottn>// - **[848bb2426](facebook/react@848bb2426 )**: Attach Listeners Eagerly to Roots and Portal Containers ([#19659](facebook/react#19659)) //<Dan Abramov>// - **[d2e914ab4](facebook/react@d2e914ab4 )**: Remove remaining references to effect list ([#19673](facebook/react#19673)) //<Andrew Clark>// - **[d6e433899](facebook/react@d6e433899 )**: Use Global Render Timeout for CPU Suspense ([#19643](facebook/react#19643)) //<Sebastian Markbåge>// - **[64ddef44c](facebook/react@64ddef44c )**: Revert "Remove onScroll bubbling flag ([#19535](facebook/react#19535))" ([#19655](facebook/react#19655)) //<Dan Abramov>// - **[dd651df05](facebook/react@dd651df05 )**: Keep onTouchStart, onTouchMove, and onWheel passive ([#19654](facebook/react#19654)) //<Dan Abramov>// - **[b8fa09e9e](facebook/react@b8fa09e9e )**: provide profiling bundle for react-reconciler ([#19559](facebook/react#19559)) //<Julien Gilli>// - **[23595ff59](facebook/react@23595ff59 )**: Add missing param to safelyCallDestroy() ([#19638](facebook/react#19638)) //<Brian Vaughn>// - **[ee409ea3b](facebook/react@ee409ea3b )**: change destroy to safelyCallDestroy ([#19605](facebook/react#19605)) //<Luna Ruan>// - **[bcca5a6ca](facebook/react@bcca5a6ca )**: Always skip unmounted/unmounting error boundaries ([#19627](facebook/react#19627)) //<Brian Vaughn>// - **[1a41a196b](facebook/react@1a41a196b )**: Append text string to <Text> error message ([#19581](facebook/react#19581)) //<Timothy Yung>// - **[e4afb2fdd](facebook/react@e4afb2fdd )**: eslint-plugin-react-hooks@4.1.0 //<Dan Abramov>// - **[ced05c46c](facebook/react@ced05c46c )**: Update CHANGELOG.md //<Dan Abramov>// - **[702fad4b1](facebook/react@702fad4b1 )**: refactor fb.me redirect link to reactjs.org/link ([#19598](facebook/react#19598)) //<CY Lim>// - **[49cd77d24](facebook/react@49cd77d24 )**: fix: leak strict mode with UMD builds ([#19614](facebook/react#19614)) //<Toru Kobayashi>// - **[ffb749c95](facebook/react@ffb749c95 )**: Improve error boundary handling for unmounted subtrees ([#19542](facebook/react#19542)) //<Brian Vaughn>// - **[9b35dd2fc](facebook/react@9b35dd2fc )**: Permanently removed component stacks from scheduling profiler data ([#19615](facebook/react#19615)) //<Brian Vaughn>// - **[3f8115cdd](facebook/react@3f8115cdd )**: Remove `didTimeout` check from work loop //<Andrew Clark>// - **[9abc2785c](facebook/react@9abc2785c )**: Remove wasteful checks from `shouldYield` //<Andrew Clark>// - **[1d5e10f70](facebook/react@1d5e10f70 )**: [eslint-plugin-react-hooks] Report constant constructions ([#19590](facebook/react#19590)) //<Jordan Eldredge>// - **[dab0854c5](facebook/react@dab0854c5 )**: Move commit passive unmount/mount to CommitWork ([#19599](facebook/react#19599)) //<Sebastian Markbåge>// - **[ccb6c3945](facebook/react@ccb6c3945 )**: Remove unused argument ([#19600](facebook/react#19600)) //<inottn>// - **[629125555](facebook/react@629125555 )**: [Scheduler] Re-throw unhandled errors ([#19595](facebook/react#19595)) //<Andrew Clark>// - **[b8ed6a1aa](facebook/react@b8ed6a1aa )**: [Scheduler] Call postTask directly ([#19551](facebook/react#19551)) //<Andrew Clark>// - **[ce37bfad5](facebook/react@ce37bfad5 )**: Remove resolutions from test renderer package.json ([#19577](facebook/react#19577)) //<Dan Abramov>// - **[2704bb537](facebook/react@2704bb537 )**: Add ReactVersion to SchedulingProfiler render scheduled marks ([#19553](facebook/react#19553)) //<Kartik Choudhary>// - **[0c52e24cb](facebook/react@0c52e24cb )**: Support inner component _debugOwner in memo ([#19556](facebook/react#19556)) //<Brian Vaughn>// - **[0cd9a6de5](facebook/react@0cd9a6de5 )**: Parallelize Jest in CI ([#19552](facebook/react#19552)) //<Andrew Clark>// - **[a63893ff3](facebook/react@a63893ff3 )**: Warn about undefined return value for memo and forwardRef ([#19550](facebook/react#19550)) //<Brian Vaughn>// - **[32ff42868](facebook/react@32ff42868 )**: Add feature flag for setting update lane priority ([#19401](facebook/react#19401)) //<Ricky>// - **[5bdd4c8c6](facebook/react@5bdd4c8c6 )**: Remove unused argument from call to jest method ([#19546](facebook/react#19546)) //<Gustavo Saiani>// - **[a5fed98a9](facebook/react@a5fed98a9 )**: Register more node types that are used later as JSXIdentifiers ([#19514](facebook/react#19514)) //<Mateusz Burzyński>// - **[f77c7b9d7](facebook/react@f77c7b9d7 )**: Re-add discrete flushing timeStamp heuristic (behind flag) ([#19540](facebook/react#19540)) //<Dominic Gannaway>// Changelog: [general] [feature] Upgrade to React 17 Reviewed By: cpojer Differential Revision: D24491201 fbshipit-source-id: c947da9dcccbd614e9dc58f3339b63e24829aca7

bvaughn requested review from gaearon, rickhanlonii, lunaruan and acdlite August 6, 2020 18:27

facebook-github-bot added CLA Signed React Core Team Opened by a member of the React Core Team labels Aug 6, 2020

acdlite approved these changes Aug 6, 2020

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Warn about undefined return value for memo and forwardRef

404a1d0

bvaughn force-pushed the issues/19548 branch from 65a5435 to 404a1d0 Compare August 6, 2020 18:50

bvaughn merged commit a63893f into facebook:master Aug 6, 2020

bvaughn deleted the issues/19548 branch August 6, 2020 20:12

gaearon mentioned this pull request Aug 10, 2020

Revert "Warn about undefined return value for memo and forwardRef" #19574

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Revert "Warn about undefined return value for memo and forwardRef (#1…

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…9550)" This reverts commit a63893f.

kachkaev mentioned this pull request Oct 24, 2020

Bug: Nothing returned from renderer when returning undefined #20089

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Warn about undefined return value for memo and forwardRef #19550

Warn about undefined return value for memo and forwardRef #19550

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Warn about undefined return value for memo and forwardRef #19550

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