Disallow reading context during useMemo etc #14648
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The previous commit check was too broad and incorrectly restricted classes from calling readContext(). This check is more precise and only targets components that are Hook-capable. It exploits the fact that `renderExpirationTime` is never `NoWork` after `renderWithHooks` -- something we already rely on.
threepointone
approved these changes
Jan 21, 2019
| // The inner check tells us we're currently in renderWithHooks() phase | ||
| // rather than, for example, in a class or a context consumer. | ||
| // Then we know it should be an error. | ||
| if (renderExpirationTime !== NoWork) { |
|
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gaearon
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Jan 21, 2019
…Mode" (#14652) * Revert "Revert "Disallow reading context during useMemo etc" (#14651)" This reverts commit 5fce648. * Revert "Add test coverage for readContext() on the server (#14649)" This reverts commit fe2ecd2. * Revert "Warn about incorrect use of useImperativeHandle() (#14647)" This reverts commit 8f45a7f. * Revert "Disallow reading context during useMemo etc (#14648)" This reverts commit 1fcbd22. * Revert "Warn about refs on lazy function components (#14645)" This reverts commit 2a084f5. * Revert "Fix typo (#14560)" This reverts commit b5a3df6. * Revert "fix typo (#14316)" This reverts commit 9c146e6. * Revert "Mention forwardRef() in <Fn ref={...} /> errors and warnings (#14644)" This reverts commit baa6d40. * Revert "Double-render function components with Hooks in DEV in StrictMode (#14643)" This reverts commit a1414e8.
jetoneza
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Jan 23, 2019
* Disallow reading context during useMemo etc * Continue allowing readContext() in classes and context consumers The previous commit check was too broad and incorrectly restricted classes from calling readContext(). This check is more precise and only targets components that are Hook-capable. It exploits the fact that `renderExpirationTime` is never `NoWork` after `renderWithHooks` -- something we already rely on.
jetoneza
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to jetoneza/react
that referenced
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Jan 23, 2019
* Revert "Add test coverage for readContext() on the server (facebook#14649)" This reverts commit fe2ecd2. * Revert "Warn about incorrect use of useImperativeHandle() (facebook#14647)" This reverts commit 8f45a7f. * Revert "Disallow reading context during useMemo etc (facebook#14648)" This reverts commit 1fcbd22.
jetoneza
pushed a commit
to jetoneza/react
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Jan 23, 2019
…Mode" (facebook#14652) * Revert "Revert "Disallow reading context during useMemo etc" (facebook#14651)" This reverts commit 5fce648. * Revert "Add test coverage for readContext() on the server (facebook#14649)" This reverts commit fe2ecd2. * Revert "Warn about incorrect use of useImperativeHandle() (facebook#14647)" This reverts commit 8f45a7f. * Revert "Disallow reading context during useMemo etc (facebook#14648)" This reverts commit 1fcbd22. * Revert "Warn about refs on lazy function components (facebook#14645)" This reverts commit 2a084f5. * Revert "Fix typo (facebook#14560)" This reverts commit b5a3df6. * Revert "fix typo (facebook#14316)" This reverts commit 9c146e6. * Revert "Mention forwardRef() in <Fn ref={...} /> errors and warnings (facebook#14644)" This reverts commit baa6d40. * Revert "Double-render function components with Hooks in DEV in StrictMode (facebook#14643)" This reverts commit a1414e8.
n8schloss
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Jan 31, 2019
* Disallow reading context during useMemo etc * Continue allowing readContext() in classes and context consumers The previous commit check was too broad and incorrectly restricted classes from calling readContext(). This check is more precise and only targets components that are Hook-capable. It exploits the fact that `renderExpirationTime` is never `NoWork` after `renderWithHooks` -- something we already rely on.
n8schloss
pushed a commit
to n8schloss/react
that referenced
this pull request
Jan 31, 2019
* Revert "Add test coverage for readContext() on the server (facebook#14649)" This reverts commit fe2ecd2. * Revert "Warn about incorrect use of useImperativeHandle() (facebook#14647)" This reverts commit 8f45a7f. * Revert "Disallow reading context during useMemo etc (facebook#14648)" This reverts commit 1fcbd22.
n8schloss
pushed a commit
to n8schloss/react
that referenced
this pull request
Jan 31, 2019
…Mode" (facebook#14652) * Revert "Revert "Disallow reading context during useMemo etc" (facebook#14651)" This reverts commit 5fce648. * Revert "Add test coverage for readContext() on the server (facebook#14649)" This reverts commit fe2ecd2. * Revert "Warn about incorrect use of useImperativeHandle() (facebook#14647)" This reverts commit 8f45a7f. * Revert "Disallow reading context during useMemo etc (facebook#14648)" This reverts commit 1fcbd22. * Revert "Warn about refs on lazy function components (facebook#14645)" This reverts commit 2a084f5. * Revert "Fix typo (facebook#14560)" This reverts commit b5a3df6. * Revert "fix typo (facebook#14316)" This reverts commit 9c146e6. * Revert "Mention forwardRef() in <Fn ref={...} /> errors and warnings (facebook#14644)" This reverts commit baa6d40. * Revert "Double-render function components with Hooks in DEV in StrictMode (facebook#14643)" This reverts commit a1414e8.
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This extends #14608 to direct
readContextcalls and adds tests. It turned out it's not super easy.I started by directing Dispatcher's
readContexttoFiberHooksimplementation so that we can checkcurrentlyRenderingFiber(which #14608 temporarily resets before calling user code from Hooks). But then I realizedcurrentlyRenderingFiberis alsonullfor classes and context consumers from which it's legit toreadContext().I struggled a bit but then noticed we already rely on
renderExpirationTime(per comment) to tell whether we're in a Hook-capable component or not. So I used that too, and only throw ifrenderExpirationTime !== NoWork(we’re using Hooks) andcurrentlyRenderingFiber === null(we’ve stepped into the user code).While I was there, I also removed unnecessary
FiberBeginWork -> CurrentDispatcher -> readContextindirection in favor of a direct call, asFiberBeginWorkitself is our own code.This PR is client-side only. I started looking into SSR but I think there might be more warts there and I want to do it separately.