Deprecate webpack 4 support

[timneutkens]

Deprecates webpack 4 support for 11.2+, the vast majority of Next.js applications is now using webpack 5 support and we've already communicated that in Next.js 12 webpack 4 will be removed.

This also removes the "Using webpack 5" from the output as it's the default.

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
buildDuration	15.2s	15s	-204ms
buildDurationCached	3.9s	3.8s	-115ms
nodeModulesSize	49.2 MB	49.2 MB	-566 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.051	2.997	-0.05
/ avg req/sec	819.38	834.11	+14.73
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.884	1.769	-0.11
/error-in-render avg req/sec	1326.83	1413.55	+86.72

Client Bundles (main, webpack, commons)

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
745.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	23.3 kB	23.3 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	67.2 kB	67.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
_app-HASH.js gzip	979 B	979 B	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	329 B	329 B	✓
dynamic-HASH.js gzip	2.67 kB	2.67 kB	✓
head-HASH.js gzip	351 B	351 B	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	4.14 kB	4.14 kB	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	318 B	318 B	✓
script-HASH.js gzip	387 B	387 B	✓
withRouter-HASH.js gzip	320 B	320 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	13 kB	13 kB	✓

Client Build Manifests

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
_buildManifest.js gzip	492 B	492 B	✓
Overall change	492 B	492 B	✓

Rendered Page Sizes

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
index.html gzip	539 B	539 B	✓
link.html gzip	553 B	553 B	✓
withRouter.html gzip	533 B	533 B	✓
Overall change	1.63 kB	1.63 kB	✓

---

Webpack 4 Mode (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
buildDuration	12.1s	11.9s	-209ms
buildDurationCached	5.1s	4.9s	-115ms
nodeModulesSize	49.2 MB	49.2 MB	-566 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.982	2.996	⚠️ +0.01
/ avg req/sec	838.22	834.37	⚠️ -3.85
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.821	1.765	-0.06
/error-in-render avg req/sec	1372.53	1416.42	+43.89

Client Bundles (main, webpack, commons)

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
16.HASH.js gzip	186 B	186 B	✓
677f882d2ed8..HASH.js gzip	14.1 kB	14.1 kB	✓
framework.HASH.js gzip	41.9 kB	41.9 kB	✓
main-HASH.js gzip	10.7 kB	10.7 kB	✓
webpack-HASH.js gzip	1.19 kB	1.19 kB	✓
Overall change	68.1 kB	68.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
_app-HASH.js gzip	964 B	964 B	✓
_error-HASH.js gzip	3.8 kB	3.8 kB	✓
amp-HASH.js gzip	552 B	552 B	✓
css-HASH.js gzip	333 B	333 B	✓
dynamic-HASH.js gzip	2.87 kB	2.87 kB	✓
head-HASH.js gzip	3.06 kB	3.06 kB	✓
hooks-HASH.js gzip	924 B	924 B	✓
index-HASH.js gzip	231 B	231 B	✓
link-HASH.js gzip	1.64 kB	1.64 kB	✓
routerDirect..HASH.js gzip	298 B	298 B	✓
script-HASH.js gzip	3.03 kB	3.03 kB	✓
withRouter-HASH.js gzip	295 B	295 B	✓
30809af5c834..565.css gzip	125 B	125 B	✓
Overall change	18.1 kB	18.1 kB	✓

Client Build Manifests

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
_buildManifest.js gzip	500 B	500 B	✓
Overall change	500 B	500 B	✓

Rendered Page Sizes

	vercel/next.js canary	timneutkens/next.js add/deprecate-webpack4	Change
index.html gzip	584 B	584 B	✓
link.html gzip	597 B	597 B	✓
withRouter.html gzip	577 B	577 B	✓
Overall change	1.76 kB	1.76 kB	✓

Commit: 6d0cba7