* Make sure to not show pages/404 GIP error from _app having GIP

* Add error for getStaticProps in pages/404 too

* Add support for getStaticProps in pages/404

* Update test

* Make sure to not show pages/404 GIP error from _app having GIP

* Add error for getStaticProps in pages/404 too

* Verify GS(S)P Serializability

* Add support for cyclic refs

* Add unit tests

* Test for error in development mode

* Fix prerender preview tests

* Fix gssp preview tests

* fix 2x test cases

* Add desired test

* fix some more tests

* Fix route manifest expect

* Fix test expects

* Test that `getServerSideProps` does not error in production

* Test that getStaticProps is not checked in production

* Test serialization check during build

* Fix export detection for serverless

* Update test/unit/is-serializable-props.test.js
Co-Authored-By: NJJ Kasper <jj@jjsweb.site>
Co-authored-by: NJJ Kasper <jj@jjsweb.site>

* Fix `getServerSideProps` Test Case

* Data requests should fail instead of rendering

* Update to use separate export instead of attaching to Component to identify GS(S)P pages

* Handle initialProps being undefined

* Update to make sure preview mode works with getServerSideProps

* Update to only parse previewData in GS(S)P mode

* Add identifier to NEXT_DATA for gs(s)p

* Apply suggestions from code review
Co-Authored-By: NJoe Haddad <joe.haddad@zeit.co>

* fix lint

* apply lint fix
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Correctly pass preview data

* remove todo

* re-do change

* fix types

* Prevent regression

* Separate Low Priority Files from Main Files

* Fix tests

* Rename getServerProps to getServerSideProps

* Remove unstable_ prefix from new methods

* Add error when legacy methods are detected

* Add legacy methods for babel transform

* Add unstable_getServerSideProps also

* Apply suggestions from code review
Co-Authored-By: NJoe Haddad <joe.haddad@zeit.co>

* Update types import
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Make sure to show error when url prop is returned for a page

* Update test and handle undefined pageProps

* Handle empty props

* Apply suggestions from code review
Co-Authored-By: NTim Neutkens <tim@timneutkens.nl>

* Update tests

* Update to not add url prop for SSG/SSP pages

* Update errsh for reserved prop

* Update errsh wording some more

* Update tests and to warn instead of error

* Update reserved prop warning

* Include page in url prop warning
Co-authored-by: NTim Neutkens <tim@timneutkens.nl>
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Add error messages for dynamic SSG page without getStaticPaths

* Update error check

* Update test file

* Update another test file

* Adjust
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Add err.sh for getStaticProps error

* Prettify error
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Clean up landed experimental flags

* Remove check for experimental flags from build too

* Remove /_errors/404 in favor of /404

* Remove unneeded check for pathname

* Update test paths

* Fix test

* Update test

* Remove test for disabled config

* Set pages404 always to true
Co-authored-by: NJoe Haddad <timer150@gmail.com>
Co-authored-by: NJJ Kasper <jj@jjsweb.site>

* Remove ts-ignore where possible

And replace by typecasts

* More accurate types

* bend cliententries in a correct shape earlier on

* comment becomes unnecessary

* add webpack overload to allow for the next.js use case

* Avoid changing public interface
Co-authored-by: NJoe Haddad <timer150@gmail.com>

This adds a `isFallback` property to detect if the page is being rendered in "fallback" mode or normal mode.
Accessed via the `useRouter()` hook.

---

Closes #10527

* checkpoint: api impl

* Add support for tryGetPreviewData

* snapshot: server(less) support

* Add X-Prerender-Bypass-Mode header support

* Pass preview data to getStaticProps call

* add TODO

* setPreviewData

* 100k iterations

* Handle jwt error

* Write out preview values

* forgot file

* set preview props

* Send preview props

* add preview props

* Pass around more data

* update yarn lock

* Fail on Invalid Prerender Manifest

* Make Missing Prerender Manifest Fatal

* fix ts errors

* fix test

* Fix setting cookies + maxage

* Secure is not needed as we encrypt necessary data

* Set on domain root

* Set cookie max ages

* Render a fallback on-demand for non-dynamic pages

* Test preview mode

* remove old build

* remove snapshots

* Add serverless tests

* use afterAll

* Remove object assigns

* fix cookie spread

* add comment

* Add error message when rewriting to dynamic SSG page

* Update comment
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Add initial SSG fallback handling

* Remove extra changes and update fallback handling

* Remove extra timeout for testing

* Update SSG tests in dynamic-routing suite

* Add racing to decide between rendering fallback and data

* Update size-limit test

* Update comment

* Make sure to follow correct route change order

* Make comment more verbose for racing

* Revert getStaticData to only return Promise

* Make sure to update URL on fallback

* Add retrying for data, de-dupe initial fallback request, and merge fallback replace

* Update to add preload for fallback pages data

* Add test for data preload link

* Use pre-built fallback in production mode

* Remove preload link for fallback from _document

* Update to make sure fallback is rendered correctly for serverless

* Implement experimental pages/404.js for custom 404 page

* Make sure to show error for getInitialProps in pages/404 in dev mode also

* Update routes-manifest tests for new value

* Make sure page404 is boolean in routes-manifest

* Rename variables for consistency

* Make sure to only use 404 page for 404 error

* Add support for unstable_getServerProps

* Apply suggestions from review

* Add no-cache header and update types

* Revert sharing of load-components type

* Add catchall test and update routes-manifest field

* Update header check

* Update to pass query for getServerProps data requests

* Update to not cache getServerProps requests

* Rename server side props identifier

* Update to nest props for getServerProps

* Add no-cache header in serverless-loader also

* Update to throw error for mixed SSG/serverProps earlier

* Add comment explaining params chosing in serverless-loader

* Update invalidKeysMsg to return a string and inline throwing

* Inline throwing mixed SSG/serverProps error

* Update setting cache header in serverless-loader

* Add separate getServerData method in router

* Update checkIsSSG -> isDataIdentifier

* Refactor router getData back to ternary

* Apply suggestions to build/index.ts

* drop return

* De-dupe extra escape regex

* Add param test

* Update SSG types and clean up RenderOpts type

* Move SSG types back to internal module

* Rename some spr related stuff to ssg

* Update packages/next/lib/constants.ts
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Remove experiment

* Add back ssr-prepass for serverless test

* Update size as they both decreased
Co-authored-by: NJJ Kasper <jj@jjsweb.site>

* fix root components import order

* import order tests

* chunks attachment order tests

* Add error for rewrite to auto-exported dynamic page

* Update packages/next/next-server/server/render.tsx
Co-authored-by: NJoe Haddad <timer150@gmail.com>

* Adjust return value

* Add delay

* WIP: rename get static paths

* Adjust logic

* Add warning

* rename constant

* Check for error when using old method

* Add friendly error message

* Test for message of invalid keys

* replace index with dots

* Add failing test

* Escape dollar signs in AMP HTML

* Update to not use replace for updating AMP_RENDER_TARGET

* Don't use loader import at top level in next/document

* Update ts-ignores

* Update `packages/`

* Update examples

* Update tests

* Update bench

* Update top level files

* Fix build

* trigger

* Polyfilling fetch and object-assign

* Polyfilling corejs object-assign

* Adding object-assign in polyfills.js. IE11 does not support Object.assign

* Fixing failing test

* Updating object.assign polyfill to fix aliasing

* Updating test case value to match new build stats

* Increasing the size of default build to 225kb

* Fixing defer-script test case to not include polyfill.js

* Revert README.md

* Re-design the polyfill approach based on PR feedback

* Adding comment and fixing test case

* Rename polyfills chunk

* Extract aliases into helper

* Remove extra new line

* Fix TypeScript typings

* Adding _internal_fetch alias

* Adjust build manifest plugin

* Build manifest plugin changes - adding a separate entry for polyfills

* Rename polyfills entry in build-manifest.json

* Remove old comment

* Fix TS

* Set key

* Polyfills already added

* Filtring polyfill.module.js

* Fix test

* Add __internal_fetch to alias rule

* Adjust name

* bump size

* ignore polyfills

* sigh

* Disallow iSSG revalidation period of zero

* Fix revalidation period in test